E38 idle tuning

[swingtan]

RE: Idle timing upper hard limits. It's what ever your "normal" timing table has in those cells.

IE, If the Hi/Low blend for {B5101} and {B5102} is 28', then the maximum idle timing will be 28'. If the blend is 26' then the max idle timing will be 26'. Raise the values in {B5010} and you raise the upper idle timing limit. It took me a while to work that one out......

Also, note {B1836} to {B1838} and {B1840} to {B1842} ( if your OS has all those... ) {B1651} and {B1652} are absolute limits in throttle % (using the logarithmic table I've posted elsewhere ). So 2% in these tables is about 18%-20% throttle when logged. The other tables are absolute correction limits in gm/Sec. In my OS, the stock settings will limit the amount of correction to 5gm/Sec, so these will limit the "dynamic" correction amounts. I still think the ECT correction should be enough to get the desired airflow though. At a cold idle of 1000RPM on mine, I have 15% throttle and just over 17gm/Sec of air flow. As for tables missing... I think there will always be "some" missing tables :p.

Simon.

[hymey]

Ok 7mm hole drilled. Far too big. Now cant close throttle enough and I get a P0068, so weld is required :(
I think I tuned the DTC out with the ETC processing tables.
But from the initial results it seems it might help. Just a FYI start small unless you want a 1000+ rpm min idle.
Also idle hangs pretty badly. Probably can tune that out with the correction tables, but I need a smaller hole anyway... Ho hum..
Definitely some tables missing!

Update: If I had a cam big enough to warrant a 1000rpm idle then Id be set. Cold start worked well. Tuned out the DTC no problem by c0805 and c0806 tweaks.
Ive had to ramp up integral corrections by a shed load and drop all my other tables back to stock. Still too much air and idle still hangs but not as bad.
Anyway, I think Ill weld her up and bung a 5mm hole in there.

Hopefully one day Ross can find a few more idle control tables and avoid such a crude method

Hi Ringram, if you send me the tune I will fix your problem. I run 7mm holes with 224/228s in 6L.

Whatever you do don't weld the hole if P0068 table sets in it will make the idle hang by a mile. I will fix your tune in 5minutes if you send it through bud,

Leave the correction values stock until you get a decent idle. If your car is setting P0068 it will idle high. You will get rid of the limp mode by turning the MAF/MAP correlation test off. You have no MAF so no test required.

With SAE.TP you can drop all the way to 12% throttle in B1652. That is VERY low. You can get a stock cam idling with it.!

So u are making a simple mistake champ. Just send me the tune and I will get it idling. DOn't weld your blade you will warp it!

BTW my car has two holes in the TB!

[hymey]

Send it through I will fix.

For cranking the engine.

Set cranking timing to 18 degrees. Cranking idle air to whatever the g/sec value is in min idle airflow.

Set max -10 in cranking timing correction.

You have other stuff messed up in the tune I will get it happening for you sound like u are having some issues with it and changing to many things to compensate.

We are here to help!

[hymey]

Again simple fix. I see you tune now will sort it tonight. But again as a rule, cranking timing, cranking idle air to min idle air values and max -10 on overshoot is the key!

I have just completed a 6L with a custom cam on a 108LSA! Yes a lot of overlap. Works awesome. I has no surging issues like the 112 LSA's can sometimes get as the 108 lobe sep is pulling air through much faster.

Will post up tonight.

Joel

[The Alchemist]

[QUOTE=swingtan;133043]RE: Idle timing upper hard limits. It's what ever your "normal" timing table has in those cells.

IE, If the Hi/Low blend for {B5101} and {B5102} is 28', then the maximum idle timing will be 28'. If the blend is 26' then the max idle timing will be 26'. Raise the values in {B5010} and you raise the upper idle timing limit. It took me a while to work that one out......

Oh FFS you are joking !!!! really....I tried this and you are correct, timing trim now goes up to 32 if "32" is entered in this table in idle zones. I had 28 in there hence my "hard" limit. This helped cold starts, thx.
Next question is, if the high/low tables set the upper hard limit at idle what does the ECU do/need with the BASE IDLE timing table? Is this just for initial desired timing?
Mike

[swingtan]

I tried this and you are correct, timing trim now goes up to 32 if "32" is entered in this table in idle zones. I had 28 in there hence my "hard" limit. This helped cold starts, thx.
Next question is, if the high/low tables set the upper hard limit at idle what does the ECU do/need with the BASE IDLE timing table? Is this just for initial desired timing?
Mike

As I said... it took me a while to work that one out. It's very strange indeed but helps a lot once you know about it.

I think the base idle tables are there to set the timing "goal" for stationary idle. Why it allows more when moving ( or non idle mode timing ) I'm not too sure about. Need to think some more on that one.

Simon.

[hymey]

Hey Swingy thanks for that tip mate. I normally just use airflow. Though this will help cold starts, It gives one the option to lock out max idle area with no correction. Again cranking idle air needs to be maxxed out aswell. Cranking timing set it to 18 degrees Hot, possibly 30 cold. When hot limit flare up timing control to -10. Experiment with the multiplier cold. Excellent work mate. Appreciate that.

To make things so much easier for the big cammed brigade. There is a trick I do with HPT. (sorry efi guys lol) EFI live does not have the tables but I am going to request them.

HPT has max idle area 1 and 2. I actually requested those to be added. But they also have a table called from memory. Max idle fail. And Min idle fail. Now this is something I do with big cams and it is very simple.

Max idle fail is 60 (this is an upper limit) and Min idle fail is 5( lower hard limit!)

Efilive does not have these values at present,

Now for hot idle running I change the ect airflow multplier to 0.01 and set min idle are to 63 still. So I end up with 0.63g/s enough to pull on the lower limit which is 5. I drill s 7mm hole and set the lower value to around 25 to 45 pending on idle setup. I simply find best idle timing(Easy to do). I play around with basi idle spark and correction to get correct idle return with no hunting or popping and hanging.

I turn the A/C on. If the idle drops to much I got into around the -128 rpm cell and set it high to like 20 degrees, maybe even 25 degrees until I get the idle rpm I desire with a/c on full lock lights on etc.

Then I focus on coast down tables, same thing but I command a higher amount of spark there so the idle does not dip below 1000rpm.

Cold start, now this is the trick we only really need heaps of air cold start to get the car going and holding say 1000rpm for a few minutes until the temp gauge goes up.

In the ECT multiplier I set it to the upper limit. So I place 1.00 in the multiplier till 68 degrees C. From 70 deg onwards we can go on the lower limit and you will not notice the transition if hot idle is setup correctly with the lower timing correction placed as previously outlined.

Again idle timing 18 degrees this time across the board. Flare control limited to -10 degrees max. And cranking idle air. Max the values out up to 68 degrees C, Set to 63 g/s. Remember cranking idle air is also limited to hard limits!

You will not notice the transition at all from high to low if the hole in the TB is correct and the limits and timing are correct.

After 68 degrees set the hole table to 0 g/s. This will pull it to the lower limit and stop the e38 getting confused on start up.

Remember 18 degrees cranking spark. limit flare control to -10 degrees and it will start and idle better then ever.

Once the guys(please) add them in. I will set it up and show you.

Cheers

[hymey]

Simon once the vehicle is rolling it transfer to "coast down spark" the threshold in my car is 2km/h so over that once I am rolling I can command different amounts of "rolling idle timing". Maybe you already know this and I misunderstood your post.

[swingtan]

Yes, coast down spark if the throttle is closed and the desired RPM is below the current RPM....

[The Alchemist]

heres my log of a full cold start and screen shot of startup and 20sec plus.
Finally, changing to 18deg cranking timing increasing the cranking idle air right up, max -10 on the rpm flare as per Hymey instructions it burst into life like the true animal it is instead of sounding apologetic then surging like a bitch lol This made the biggest difference I think to the actual idle quality immediately after starting.
Also allowing idle spark trim to hit 34deg also stabilised the idle > thanks Swingtan.

My TP% was still only 20.4% even though I increased 51/52 up as high as 2.7 , I also put "1"s in the airflow multiplier up to 68deg and made no difference to TP% yet in open loop with the min air flow maxxed to 63g/s I can command the hard limit of 22% easily. So I can only achieve 860rpm even though my desired is 950-1000 at startup but its steady as a rock now! I will check again in the morning without resitting idle learn and see if it commands more
Finally a question: immediately after startup the AFR sits as 14.4:1 for 15sec every time when cold then steps down to 13.5:1. Changing IVT multiplier only causes the 13.5:1 to dip into the 12's and makes no change to the 14.4:1 section. Is there an afterstart enrichment setting somewhere or is this altered by changing cranking fuel settings?
Any ideas? I just think it would be better a bit richer as the idle doesn't truely stablise until it richens up to 13.5:1.
Cheers,
Mike