E38 idle tuning

Excellent info there ringram!. I'll have a play with this as I've been hunting for a low speed, low load surge for a while now. I've also "reduced" the commend cranking air in my car and found it starts better.

On a different note, I thought I'd offer a tip on idle fueling for those still running a MAF. It seems that on some E38 OS's, the ECM will drop into SD mode for idle fueling and no amount of MAF adjustment will help. I get the feeling that it's what is termed "closed loop idle" in some OS's, where the "closed loop" does not refer to O2 trims, but to the airflow bias between MAF and MAP. At certain idle settings, the MAP takes precedence even if the MAF is not in a failed state. I'm still working on this one though.

Simon.

Quote:

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Originally Posted by ringram

Ok, update from me. I decided to epoxy up the hole and retry perhaps with a smaller hole.
BUT after speaking to Jessie from Waitforme at PRI did some messing with B1650 Max ETC area and what do you know. All seems well now.
Way, way better on cold starts than before and NO HOLE! I told it the area was smaller. Im guessing all the tables we cant see and corrections etc now think the throttle is small so it has to move the blade a larger amount.
I cant remember if Jessie said to make the value larger or smaller, but figured Id play around anyway.
So before anyone drills anything Id try this table first.
I can now drive at idle in 6th gear at 32mph on the flat, no jerking or lurching. Mind you cam is only 227/243-113

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Thats good to hear Ringram, I noticed you had values of over 2 in max idle area which would not work with a hole in the TB, with the earlier o/s you can get away with a smaller hole(or in your case-no hole) but I can guarentee u I could get it running better with a hole. The blade just trims to far. Trust me after years of hard work on this and fixing a crap load of them (I have learnt the hard way) I can honestly say I have seen people come to me very happy with there tuners results with no holed TB to then drive a car with a stock like cam. I can only tell people the method I use. Just like a uni lecturer they give out the info weather the student can grasp it and make it work for themselves is another thing. But all in all I am glad you got it running and sorry if I lead you down the wrong path..again though as shown by the video before a car 220s duration on 112 lsa in an early o/s e38 with 7mm hole idling like stock. Cold start is relatively simple aswell. Infact I have a car in the workshop here with a 230s cam on 110 and drilled it 7mm once its tuned will post up some vids.. BTW I am glad guys are reading this stuff and messing with the max idle area tables.

Cheers

No worries mate. As you say as long as everyone has the tools in their tool bag they can select the one that works best for them :)

I spoke to Simon the other day about integral and proportional tables integral being short term and long term being proportional. If anyone has read the thread you will see some stuff on PI controllers and how they work with the 'P' being a learnt value and 'I' being a direct input by zeroing out the P table like you can do with long term idle trims in LS1s this allows any memory to not be used and allows the car to run on the direct value. I myself tried this the other night and found the min idle air much more responsive to changes without the need to reset the pcm all the time so good stuff Simon.

I have a vid here that I am experimenting with I have setup a 4 barrel manifold on my VE-G8(248-254-106 cam 40 deg overlap) and I can switch from carb back to efi in like 2 hours(yes a carb) just by changing the regulator and reconnecting fuel rails and some minor tune changes. I am amazed at how well super sedans run with massive cams and idle at 800 rpm and just bump over but super responsive with there competition carbs and powerful ignition systems. So in a sense I am playing with the e38 to obtain a correct idle while no injectors are there just thought I would show people it can be done. Vid is a little dodgy but its just an update on the progress(getting there). The car has a nitrous setup can go upto 300hp. I also have a large garrett turbo here I would like to setup blow thru carb. Will see how we go.

http://www.youtube.com/watch?v=EFqKZ_CWAok

http://www.youtube.com/watch?v=ORiZ5kd1580

sorry bout ordinary filming lol

Ringram: I've made some initial tests on a "smaller" cam (220/224) and found that B1650 has an interesting effect. I like it so far but the verdict is still out on the light throttle surge. I found that reducing it too far, resulted in a hanging idle when cold and the normal ECT correction table needed a lot of work to try and correct it. So I increased it to about 80% of the stock value and it seems fine. I still get a small amount of surge so may need to work on some dynamics again.

Hymey: Those tables can give some good results, don't they. As mentioned, I zeroed out the few cells around 0 RPM in the Proportional table to help with idle control. I'd found that my engine idled better if it was commanding slightly more air than it really needed. The problem was that the Proportional table would pull too much air out and the idle would go rough. I was consistently adding 0.5gm/S to the min idle air, then it would learn down and run rough again. So I zeroed the cells and all is good now. Min idle airflow is what I want it to be and the ECM does not remove addition airflow.

Simon.

Simon, It works wonders, infact I seen it zeroed out in a stock 09 VE clubsport OS. So HSV been playing too;). They definately like to idle better with a little more air and lesser amounts of timing. The cams people mainly use arent that big and don't call for large amounts of timing. The motor needs to breath at idle. You just command what idle air you want and it responds basically , the integral tables do a fine job trimming the air and getting as fussy as we do now means proportion is not required. And it sure does mess things right up at times.

The only real fix for surging I have found is lowering B1651 a little and running in openloop. This helps a lot.

Also It has a lot to do with the engine. If I put a 230s cam in dot to dot and cam is retarded it will surge in CL. If I then fit a new timing chain and degree the cam with a rollmaster etc So it is advanced say 2 to 4 degrees. No more surging in CL in most cases. 3.9 and 4.11 diff gears will eliminate it with a M6 once you have the tune right they drive amazingly like a stock car or better!

Joel

Quote:

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Originally Posted by swingtan

Ringram: I've made some initial tests on a "smaller" cam (220/224) and found that B1650 has an interesting effect. I like it so far but the verdict is still out on the light throttle surge. I found that reducing it too far, resulted in a hanging idle when cold and the normal ECT correction table needed a lot of work to try and correct it. So I increased it to about 80% of the stock value and it seems fine. I still get a small amount of surge so may need to work on some dynamics again.

Hymey: Those tables can give some good results, don't they. As mentioned, I zeroed out the few cells around 0 RPM in the Proportional table to help with idle control. I'd found that my engine idled better if it was commanding slightly more air than it really needed. The problem was that the Proportional table would pull too much air out and the idle would go rough. I was consistently adding 0.5gm/S to the min idle air, then it would learn down and run rough again. So I zeroed the cells and all is good now. Min idle airflow is what I want it to be and the ECM does not remove addition airflow.

Simon.

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Another note B1650 if changed will alter TP% reducing it actually increases TP%, so if you get 9% TP% you maybe getting 15 or more % just a guess really.

I think it will act on some hidden airflow calculations. (ie) I need 10g/sec so given ETC area y I need x% ETC.TP to deliver the 10g/sec, of course a "smaller" throttle means greater x% for airflow.. So its tricking the ECU, but whatever works :) Given mine is skewed due to limited IFR another skewed value is ok. Thanks to Jessie for the heads up.

Sounds good, I have read some of the HPT guys doing it, A lot of guys there having issues with things it is easy to mess things up. I redid a car last week had been to so many shops I had to start again. The main thing is the hard limit, even if you change the multipliers the hard limit is still there changing b1650 it still thinks its the same but you get more percentage. Just make sure it is getting full throttle when it should be. Cold starts is easy to sort I am more concerned how your idle is with the TP% trimming. As simon mentioned he has also opted to not drill his which is a personal preference. But he also said his idle does move around a little because it steps 0.4% at a time. I'm a little different and I the way they end up changes the note of the car, A lot of commodore owners approached a friend of mine during powercruise asking the same. The airspeed buffer works wonders:)

Another thing that must be considered is dynamics. Again I base these ideas on speed density. Tuning the MAF at idle takes longer. SD gives a better idle with big cams. Also most tuners in US are using MAF based tunes. When they go over to speed density with e38 they are treating it like a ls1 o/s(not altering dynamics) and if dynamics isn't right it results in very poor drivability and lag in throttle response. WOT tuning is also an issue. With stock dynamics and SD the car will ramp up a nice number and afr curve then on the street low gears will be lean at WOT with lean spikes during shifts resulting in very poor performance. The first thing they do is put the MAF back on in which if they don't know what there doing is a very good idea.

Yeah I think cold start dynamics needs tweaking. More fuel required. Though once warm its fine. I have too much throttle response with 440 cubes and a 227 cam as it is.

Whats your afrs at cold Rich?

cheers

Joel

If I ever get my car back from the guys learning at my expense Ill tell you!
I took the WB out for warranty work a while back. Ive been without my car for basically a year, its just gone back for an oil leak less than 1000 miles after a £10k rebuild.
Not pleased.
Anyway, Ive no garage, so need to wait until its semi dry to roll under the car and fit the WB again. Ill get some NB O2 MV info for a rough idea if/when I get the car back!

Despite originating in Australia it is a British car now so it is supposed to leak oil. Seriously hough, that is very bad for the amount of time and money you've put into that thing. I take it back now, it may just have been cheaper to get the ZO6 :)

Is it a rear main leak Rich? I have heard some guys puting the reverse lip seal in back to front to combat oil leaks, especially with engines with forged pistons with larger ring gaps and piston to bore clearance, they tend to have a little more blow by and can cause this.

Just an update, Thanks to Simon and a few tips(which were actually brought up at the beginning of this thread). I was able to get my best drivability results with this cam 6L L98 upgrade. The cam is a 233 238 on 110+2 @ .600" lift. After I installed the cam I nearly died when I seen how minimal the ptv clearance was on the intake. All I can say it is safe for a race engine and more then what some people run so I spent a bit of time trialling differnt pushrod lengths to minimise preload just incase it gets valve float and pumps up. After a few hours I was very happy with the valve train setup,

This cam has 15.5 degrees overlap the end result I am very pleased with, performance of the engine is the best I have done "cam only" by a long shot, but the drivability was also the best I have done. The moderate duration tight lsa cams work very well and will behave if tuned correctly.

Idle was very simple. This time proportional tables zeroed out, 6mm hole in TB. B1652 1.15 and B1651 0.6. Integral tables, well looks like GM sacked there old tuner because they look a lot different, and it appears to me there tuners are learning the e38 at the rate which everyone else is...very slowly. lol. I tweaked the coast down integral table making it a little more aggressive, timing correction as per normal, 15 degrees idle timing, idle air was 8 g/s(mind u I didnt even follow the steps I normally do I just plugged the values in above and left it) Getting rid of LT idle trims helps a lot. Makes it so much easier. I ran 30 degrees in coast down table and ran less airflow on coast down to stop the chugging around roundabouts. Drivability tune was then complete but I decided to go on a 20 km fuel economy course and just keep an eye on the engine parameters. In 6th gear at 1500 rpm the car sat at 100km/h but it had a surge that was annoying and wasn't helping economy. Typical of a cam of this size. The air fuel was on the rich side in the high 13s, I tried even 13.2 it still had the problem. I new then there was a reversion and atomization issue in the chamber. The Ls7 injector does not have the best spray pattern. I decided to follow some ideas I had doing aftermarket engine management and that is to trial injector timing. By firing the injector earlier while the valve is still closed it gives the fuel more time to atomize. In GM's stock tune it is setup to allow for maximum fuel economy and emissions. A late injector fire that leaves little amount of fuel residue on the port wall.

A trick with injector timing is to advance it till the afrs are at there richest for the given pulse width. This proves that all the fuel is atomized that enters the chamber. If you keep advancing afr can drop off a little leaner which means the fuel maybe suspended on the port wall. Standard at 92 ect the injector timing is 220 degrees then the rpm table adds to this as rpm increases. I was able to go up to 400 degrees total at idle and cruise then build to around 480 at peak rpm. This cam took a lot more lead then most others do as well 31 deg at peak torque was MBT. But cruise at 38 degrees was terrible. I went upto 50 and it still wanted more but the engine did love 50 at cruise. With the injector timing and ignition timing dialled in the vve took some more work. I was running much richer this was a good sign, I was able to lean back to stoich at cruise and have perfect drivability. Running 30 degrees in coast down timing and correct coast down airflow eliminated any chugging on and off the gas. I stopped for a quick drink and let my mind rest...just for a minute and made a flash for minor timing changes. On the trip back home over 20km of country and then city driving it was a totally different car. It drove like stock just as it did when the customer dropped it off. I was very happy with the outcome. From 1000rpm in 6th pulls away like a stock cam,Most stuff of this size carries on like a pork chop! All up 6 hours work on drivability. Airflow , timing, vve and injector timing all playing equally important roles. Injector timing makes a big difference on high overlap cams. You can reap awards with aggressive cams and drivability if you focus on these areas.

Cheers

Joel

Joel what settings do you normally run for "airflow correction coolant multiplier"

VEV8, you need to run what the engine wants and every engine combination will be different. It's also very dependant on your base idle airflow. A guide for working out that table is to log the spark and see how it compares to the tune settings. The ECM will try and control the idle speed by adding or removing spark advance. If the logged spark is higher than the tune settings, add more air. If the logged spark is lower than the tune settings, remove some air. So all you need to do is to watch the spark as the ECT rises to see what sort of airflow is wanted. Remember to rest the learned data before trying this though.

Simon.

Thanks Simon...So it doesn't necessarily matter what the factor is, i can just alter minimum idle airflow to suit. But does the factor also play apart at higher rpms as well
I already knew about watching average base spark at idle to get an average airflow required.. originally my OS was a factor of 2 & was scaled down to a factor of 1 at full operating temp.. Later OS i seen were 0.5 down to .25

My setup is a 224/228 cam with a 5mm hold drilled in throttle body,13* idle spark.... with my original settings i had a minimum idle airflow in the 6's (which i thought was quite low for that cam) and still had a rather high idle

I do have it idling quite well using a setting inbetween those two original settings, just wasnt sure it was a common rule to change this setting or just change minimum idle airflow only

Try zeroing the proportional table. It uses a PI controller. P being proportional learnt data. You can use a very slight correction factor in integral tables. And moderate timing correction. The e38 is so fast it will try and adjust timing to maintain idle speed. If the rpm dips way to fast it is a sign the min idle airflow is to low. If it hangs or timing is very low try removing some timing. The reason why I change B1652 and 51 is they have a big effect on drivability. But I run B1652 high enough that it will allow enough air on cold start. Usually 1.20 B1652 0.7 B1651 is a good combination with around 7 g/s across the board in min idle airflow. I have tried every combination possible with idle tuning I always end up around here. There is a very high possibility that the "learned" data will still be there, ie the Long term idle trim. You have to zero this out in the tune to get it right. 6g/s-7g/s is about right. Some people have had good results not drilling the TB aswell. But there min idle air will be much higher. I personally get them idling better with a hole but everyone has there own methods. Not zeroing learnt data will give you a world of trouble. The main method I use will allow you to find best idle air without worrying about the learnt data but when max idle area is raised the idle lifts back up. Thats why if I drove around for a few hours and then raised the max idle area value the idle would not hang as it had learnt correctly.

As simon and I discussed a few months ago. Zeroing proportion is the right thing to do. (All proportion tables) Then you will be very close.

My email is [email protected] if you want me to look over your tune feel free to email me or Simon. We don't charge here lol , just help each other out.!

Quote:

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Originally Posted by VEV8

Thanks Simon...So it doesn't necessarily matter what the factor is, i can just alter minimum idle airflow to suit. But does the factor also play apart at higher rpms as well
I already knew about watching average base spark at idle to get an average airflow required.. originally my OS was a factor of 2 & was scaled down to a factor of 1 at full operating temp.. Later OS i seen were 0.5 down to .25

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Yes, it does matter. The colder engine weill want additional air flow to help it idle and the ECT correction factor works across the whole base idle airflow table.

Quote:

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Originally Posted by VEV8

My setup is a 224/228 cam with a 5mm hold drilled in throttle body,13* idle spark.... with my original settings i had a minimum idle airflow in the 6's (which i thought was quite low for that cam) and still had a rather high idle

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A 5mm hole for a cam that size is massive, way too big IMO. It'll cause all sorts of high idle and hang issues that may not be correctable in the tune. I'm running a 220/224 with no hole and I can tune it to idle like a stocker or have a big cam lope. I'd also look at increasing the base idle spark toward 20' to help with the idle. Don't forget to adjust the high and low spark tables to suite though.

Quote:

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Originally Posted by VEV8

I do have it idling quite well using a setting inbetween those two original settings, just wasnt sure it was a common rule to change this setting or just change minimum idle airflow only

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I've altered the ECT tables a lot, as I've done on most other tables..... When you mess with the mechanics of the motor, most of the tune settings will need to be tweaked to suit the changes.

For comparison:

My hot idle is 700RPM
Min airflow is set to 7.8gm/S

For B1602: fromt an ECT of 80'C down to 20'C I have a steep curve startingfrom "1" @ 80' and rising to just under "1.7" @ 20'. The graph angle then drops off to a value of "1.8" @ -140'

The E38 and 6lt motors like to be over fed idle air if you want it smooth. The E38 seems to do better at reducing idle speed, than increasing it, so err on the higher side and it will be easier to tune. Also as Joel says, for B1845, zero out 2 to 3 cells above and below "0" for each "idle correction type" then blend the remain cells. Once you have optimised the idle tune, the Proportional table becomes less important.

Simon

They definately like more air then less, I normally run a hole around 4-5mm for that size stick to get them idling how i like and end up around...6gm/s with a dead smooth idle at 800 rpm and 13.5-14 afr, 15 degrees timing (no correction) and zero lope. That size hole wont cause you any dramas if u set max idle air up correctly and min idle air. Twin turbo stuff with stock cams I drill 3mm holes to help the surging at idle and pulsing by the compressors.

You will find they like more air then less. My 248-254-106(admittly a carb) using stock pcm for spark idles at 20 degrees timing at 800rpm and NO spark correction, And it idles like a 224-228 would in LS1 terms at 14:1 afr and idle very smooth. The trick to this is consistent idle spark and airflow. Any changes in airflow and spark will disrupt the idle to a degree and cause it to hunt up and down by 50-100rpm. My carb has a 4mm hole drilled in each butterfly (yes four of them) so they sit in the correct position with 40 thou of the transfer slot exposed. My TK cam had an 8 mm hole in the TB I had to keep going bigger with the airflow "maxxed out".

I still prefer the original method of maxxing out max idle air. I can arrive at the point a lot faster. The integral correction is still taking place otherwise I try to eliminate that. The amazing thing is if you "lock out" the air you can then push the timing up and down(with no correction) while datalogging and engine running, I keep the air fuel in the high 13s and then raise the spark up and down until I get the best idle vacuum. In most cases then I run very minor correction in both timing and throttle like -3 deg max for timing and 0.080 for integral as a max number. Thats how I get them with a standard idle. Usually at the drags/etc combined with varex mufflers it passes as a 100% stock engine at idle. Fuel economy drastically improves around town and it really passes as a stock car to drive, Most people even if they love a tough sounding engine always go this way as it is so much better to drive. Most tuners just try to get the car driving and eliminate hunting and stop there. Go beyond that. Lock airflow, adjust timing with DVT. get in open loop Note down the max idle air, and adjust timing, increase air try different timing again. Once you arrive there establish min idle air and get the corrections to a minimum with a bypass in the TB. Cold start and drivability it all goes hand in hand.

Thanks Joel & Simon... i am pretty close now.. i zeroed the proportional table, set max idle air to 0.7 & 1.0, 15* idle spark, warm idle at 770rpm, 7's in minimum idle airflow, coolant modifier is 0.6 when warn (still had hanging idlle & low spark with anything more then that)

Its very close now i think.. may need to look at spark correction in gear setting to get it even smoother

Oh it's an auto? Guess what, autos in gear are the easy ones to tune :p. The additional load of the auto helps smooth out the idle a lot. Good news that you're getting close though.

What o/s is it some of them run 0.25 with the coolant multiplier hot and 0.5 cold. Others run 1.00 hot and towards 2.00 cold. Why? I dont know. If I use values from my o/s which has 1.00 and put them into an o/s which has 0.25 at full operating temp the idle hangs! There still both e38s and both end up with the same min idle air but the multipliers are different. Just something I picked up. If u do want to experiment with a smaller hole I have a spare TB here somewhere I can send down to u.

You can also setup B0148 for OL fuelling tune the car with that then enable PE at 90kpa. I have great results doing this. Use Simons VVE tuning guide. I have been chatting with Girch from LSX tuning, he runs 90% of his VE;s with the MAF. Something Simon and I have preached all along and I do remember Girch actually disagreed with me on this 3 years ago but 12 months ago he came around and admitted that MAF tuning is the go and will deliver the same rwkw top end and have much better drivability. Something I thought I would add if you are currently in tuning mode. To put in perspective Simons engine is the most tuned LS engine in the world by far I would think, He has tried all combinations in different cells and still goes back to the MAF. It does take longer to get right as you dial the vve in first then scale the maf. But maf tuning is definately fun and enjoyable and the fuel curve is rock solid and consistent with awesome response. THought it would be wise of me to preach it to you! You can also command a 16:1 stoich in OL MAF and use B0148 to multiply it like a ls1 cos. Run it lean at 15.5:1 cruise and 14.7 idle etc. The OL maf has better results the dynamics work so much better and the car has better partial throttle feel which helps a lot at cruise.

BTW I live in Gladstone another QLD e38 tuner!

Cheers

Thanks Joel,

Im currently running CLSD (dont have any experience with maf tuning) and running a reasonably rich VVE and bringing PE in earlier 65/70KPA to be safe.. I will post my tune for you guys to run your eyes over and see if anything obvious needs doing that i have missed (Dynamics ect).. I would like to run a little leaner in the cruise cells and idle for fuel economy

current tune

Attachment 10624Attachment 10623Attachment 10622
Hi Guys,
Got this supercharged ute back with starting issues. TVS2300, mild cam 230ish, other supporting mods etc. What its doing is: the 1st cold start starts perfect and runs no problem, takes a throttle, mixtures good etc etc, let it run for a while say to 40 to 50deg C, turn it off and start again immediately it will start fine 1st crank but as it comes down to idle it just stalls and each successive try to restart it gives the same stalling issue. Walk away have a coffee calm down, try it again and it starts and runs perfect. I have included a log and what is most noticible is:
on the 1st start of the day and the problem ones is that the IPW drops out to 0.9ms just after starting and the LOAD drops out as well to almost nothing even thoug the engine is at 1000rpm or so. Pumping the throttle does nothing as the engine is on its way down by then and the IPW just keeps sitting on 0.9ms.
The ECU is configured MAFLESS with the MAF unplugged.
Any ideas on where to look? Thanks,
Mike
http://forum.efilive.com/images/misc/pencil.png

Quote:

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Originally Posted by The Alchemist

Attachment 10624Attachment 10623Attachment 10622
Hi Guys,
Got this supercharged ute back with starting issues. TVS2300, mild cam 230ish, other supporting mods etc. What its doing is: the 1st cold start starts perfect and runs no problem, takes a throttle, mixtures good etc etc, let it run for a while say to 40 to 50deg C, turn it off and start again immediately it will start fine 1st crank but as it comes down to idle it just stalls and each successive try to restart it gives the same stalling issue. Walk away have a coffee calm down, try it again and it starts and runs perfect. I have included a log and what is most noticible is:
on the 1st start of the day and the problem ones is that the IPW drops out to 0.9ms just after starting and the LOAD drops out as well to almost nothing even thoug the engine is at 1000rpm or so. Pumping the throttle does nothing as the engine is on its way down by then and the IPW just keeps sitting on 0.9ms.
The ECU is configured MAFLESS with the MAF unplugged.
Any ideas on where to look? Thanks,
Mike
http://forum.efilive.com/images/misc/pencil.png

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So it starts up after initial start up. Thats a good thing, but what is your Min airflow set at? Also your airflow correction to coolant multiplier may need a tweak.

I wouldnt know where to start on the IPW

I had this the other day, There are some tables that help the engine recover airflow if it dips. B1833 and B1844 you can set these to less then 1.0. It seams a strange issue. Remember with the engine colder it needs more fuel on cranking then hotter. I have found that the cammed engines require much less fuel on crank . B8062 try this set down to 75%,

If an engine does this it normally means it is performing tests to see if the maf is there, the e38 will perform these tests over a few seconds on start up. Some engines actually are more sensitive then others ( and some e38s) unfortunately I have found that all cars and e38s respond differently, they all throw curve balls so when you think you have it nailed it comes back and bites you.

I think it is definately fuel only issue before you change any other settings try this.

C0310 set from 1 to 0.

C0312 set from 400 to 100 rpm. Ensure all other parameters in maf diagnostic tables are completely stock. I have seen this scenario on my car.

Make sure P0101, 102 and 103 in DTC type are not set to not reported, they should be B: 2 trips, emissions related or C: Non emissions.

I had a chat with Mike yesterday and after going back and forth a bit, Mike realised that it only occurred when the MAF was disabled. We reset all the DTC types and then tweaked the MAF tests to ensure the MAF was failing and it all came good. We think that the ECM was taking too long to fail the MAF, so it's think there was no air flow, pull the fuel out and then by the time it realised the MAF was dead and it swapped over to the VVE, it was just too late and the engine died. After tweaking the MAf tests, it's all good now.

Simon.

I thought so it happens a lot with e38s but i set the timers all to 0 and the test enable at 100 rpm in all of them now and they fire right up.

cheers

Legend !. Thanks Swingy...
Now if I could only get the throttle to open more than 20.4% at any given time to help cold idle reach target of 900rpm .....Tried B1651 52 at 4.5 and still no improvement...any ideas
?

Quote:

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Originally Posted by swingtan

I had a chat with Mike yesterday and after going back and forth a bit, Mike realised that it only occurred when the MAF was disabled. We reset all the DTC types and then tweaked the MAF tests to ensure the MAF was failing and it all came good. We think that the ECM was taking too long to fail the MAF, so it's think there was no air flow, pull the fuel out and then by the time it realised the MAF was dead and it swapped over to the VVE, it was just too late and the engine died. After tweaking the MAf tests, it's all good now.

Simon.

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This is where I get stuck and I must say I am a bit at fault for not mentioning the different o/s. I am in bed with the flu today and while it sux I get to go on the forum lol. B1602 varies from o/s to o/s some are topped out at 0.5 cold start others are at 1.0 cold start. A lot of the 2007 cars and also the VZ e38s have it to 1.00 at cold hence why they go the bigger hole they have to much air. I use the later table in these cars and run the bigger hole and they idle very nice. I have done two this week, one I built the engine it has a 239 239 lsl cam and runs in SD closed loop, the other is a 2008 VE maloo I put a 230 xfi 230 xer 111+2 cam in it. They are both well behaved. What I do in some cars(when I am time limited) is turn off the proportion which is the learning parameter, leave integral stock and flatten the hole min idle airflow table and tune for best idle air at 800 rpm. Then also also at 1000 rpm. I set the idle at 800 then put 4 g/s higher in the 600 rpm table, 2 higher at 1200 then a 1000, and 3 higher at 1600 and set max idle air at 1.50. This combination gets me in the ball park. I then push the multipliers around, So I get it idling at say 800 rpm and raise the multiplier till the TP% comes up and it hangs a little then back it off .05, see how it looks then .1 from the target and I know my bottom hard limit is reached. Doing this with a 5-7mm hole with mid size cams makes them idle so smooth and when i post the vid up you will see why I still use the larger holes, they just behave so well. Max idle area will change that upper limit to a degree but once you hit the upper limit thats it which changes in some o/s. My only suggestion is you try the multiplier B1602 in cold ects. Try and raise them it may come up to 21-22% region. It may work or may not I have not had the issue.

Another thing with maf tests in sd mode. If you have the airflow squared away with the maf, you have the scale right, and the vve correct. Sometimes when you disconnect the MAF you will notice after 4 seconds or so you feel you have no throttle and it bogs a little then goes. That is the maf still doing its tests. I alter the diagnostic tables aswell to stop this.

I remember back in 08 when I was drag racing my car- bolt on at the time I was stopping it starting it waiting to go through scrutineering and I was starting it engine would conk out and stall, then I would reflash it would start. Then stop a minute later same thing would happen just like your customers car. The scrutineer was going off , I ended up getting it started and just not turning it off, I eventually worked out to drop the timer, The VZ 1 meg o/s do this aswell.

Cheers

" My only suggestion is you try the multiplier B1602 in cold ects. Try and raise them it may come up to 21-22% region. It may work or may not I have not had the issue."
Hi Hymey thanks for your help ...this table I already have at "2" up to 32deg C as per an earlier suggestion you made a while ago....20.4% seems to be the max it goes to .....
you can see how it stays on 20.4 right up to about 55deg c before the spark has lowered enough that the TB starts to drop to 19.5 and so on .... Even when fully warmed up and you engage drive but remain stationery the TPS goes to 20.4% and the timings at around 28 deg to try to acheive target idle of 800rpm...

I've been playing in Excel a bit to try and confirm . deny a theory I came up with when talking with Mike yesterday. My theory is that the E38 uses both absolute throttle blade position and effective throttle area (as a percentage). But there is no indication as to which is being used when. This helps explain the old PE TPS graph that I went through a couple of years ago.

Anyway, I've been plotting the data out and it seems to fit in a general sense, but it's not quite there. It has helped explain a little about the hole drilling method though....

When calculating the absolute blade position and comparing it with the effective throttle area, we see that at low throttle openings, the effective area rises sharply compared to the blade position. This is because the blade tip moves through an arc from the top / bottom of the throttle body, toward the centre line. The throttle effective area is then the "gap" between the blade and the inner surface of the TB. Initially this gap widens quickly, but after a certain point (about 35% of blade position) it slows down and the change in effective area nearly matches the change in TP %. Then a short time after, the effective area changes slower than the TP% (about 65% of blade position ).

How this relates to the holes in the throttle blade can be seen when looking at the nominal Idle TP%, seeing the matching effective area and then looking at what the hole does to the situation. Here's an example.

My car normally idles at around 6% as indicated via the ETCTP PID. This gives me 8gm/S of idle air and all is well. At this pint I have an effective throttle area of about 21mm^2 which is 0.44% of the total throttle area.

If I drilled a 5mm/Dia hole in the blade, I'd introduce an additional 20mm^2 of effective throttle area, which would double the effective throttle size. So I'm going to assume the ECM will almost close the throttle to maintain the desired airflow. At this point, the ECM can not 'reduce' airflow, as it can't block the hole in the TB blade. So you have effectively removed the ECM's ability to reduce the airflow below this point.

Personally, I've never drilled a hole, possibly because I've never had a car with a big enough cam to need it. We know that the E38 likes to over feed the motor with air, as the engine seems to idle better, so the hole seems a good method to hard limit the minimum air flow. I'm pretty sure you can still do it in the software, but you can't make the hole smaller in software....

There are a couple of other things I'm still pondering....

The difference between {B1650} and {B1701}. One is set for a 78mm dia throttle and the other for a 102mm Dia throttle. Why the difference? Something to think about.

Simon.

Yeah depends on the B1602 parameters simon. If I run no hole, it idles quite high percentage, if I drill the hole it reduces by 4%, this is real testing though. The only reason I do it is to stop the pulsing of the air at idle, you hear the slight air differences. So if I use sae.tp it idles at 20% idle with say a 232 234 112 cam. I only have 1 % left for cold start. If I drill a hole its back to 15-16% roughly. But the issue is with the L76 o/s is they won't idle less then that region, whereas the later o/s will. Hence why they have "0.25" at 92 degrees in the B1602 multiplier. Change to this like Holden did in all there o/s, then 8 g/s really is much less g/s and you get real world figures. All the cars I do idle stock even with 239 cams, they wont get there otherwise. I have tried the car idling hot. No hole, And then worked on the integrals for two nights straight. Im bipolar and had a bit of a manic stage for 48 hours of solid e38 tuning a week ago, I tried the stock B1602 settings and then worked hard on the airflow tables and integrals also altering integral limits (which helps) I would aim first at a thousand and it idled OK, but the rpms moved around slightly and it was very choppy. I would increase the hole, alter the airflow tables and also changed the B1602 settings to the later setup, and the car progressively got better. I also done away with the L76s horrible pcv system and went to the later L98 setup and valley cover. I just kept going bigger (I have a spare blade) with the multiplier set to 0.35 max at lowest till I found the hard limit, then went down to 0.25 at 92 degrees, and min idle air went

10.00
10.00
6.00-----800 rpm
7.00-----1000 rpm
9.00
10.00

Now big cams and blowers need a TONNE of air at cold start. I have plenty at 20.9% cold start just like a stock car then work down to 6 g/s at hot like a stock car so the whole system is essentially working factory like. You can change the effective area values. I have never changes these and dont want to alter wot settings which it may do?

I ended up with 7mm in the 239 car. I tried going smaller just to test it as a few guys with bigger cams then this car suggested they had but I ended up with the best results doing this method. I never used an excel sheets or data logs. I just listen to the motor and do whats best for it and the customer and they drive stock. The bigger hole also makes them a lot smoother on transition and also start a lot smoother. The main reason is for the airflow buffer. Simon your car would have a larger area going from the passenger rear tappet cover to the manifold which will act as a hole itself and give extra air plus act as a buffer. The L98s/LS3s have the later restrictor in the cover which doesnt appear to give any more air. If I block it or not it does not effect idle timing. If I did that on Bens L76 it would change the timing quite a bit, just thought I will let u know that. I am pretty sure I have it covered now to the best of my knowledge. If I started again on this thread I would change a few things I do but overall it is the same out come and I think to this day I am pretty confident with what I have done with idle tuning. I have been thrown a lot of curve balls. I know some guys like to change things just in the tune but it is still a motor, like make the cam timing retarded and intake biased and you will work a lot harder in the tune to get it right. I have a method that is 100% proven, the only thing I do differently now is ensure the L76 pcv systems are modified and also work on the B1602 multipliers to help set upper and lower hard limits. I do also do what Simon does and that is zero proportional tables and keep integrals populated and play a bit with that method aswell as max idle area. The rest just comes up with the tuners ability to see the problem as it arises and how to go about fixing it.

so it seems that 20.4% is THE HARD UPPER LIMIT for my Max idle % ? Does this sound about right...ie even increasing b1651 52 from "1.8" up to "4.5" did not change the max idle over 20.4% at any given time....Looks like drilling a hole in the TB IS the only option left for me ...surely other people with S/Chargers must have had similar problems?

Try increasing {B1650}, maybe it'll allow for more throttle.

I had same issue, not enough air no matter what min idle airflow. As above b1650 definitely puts more air in.
438 cube with 230\240 cam.

Thanks ringram, I thought that may work. Was I right with increasing B1650 to allow for more air?

Simon