Procedure for turning off MAF and forcing open loop for SD?

[AllCammedUp]

Would someone mind to post the parameters that need to be changed and what values they need to be changed to in the TUN file in order to turn off the MAF and force open loop in order to do speed-density tuning?

I've been looking at the {B4205} - Closed Loop Temp Enable - table, and thought about making that table something like 255, but I didn't know if that's the proper way to go about it. Not sure on the MAF - didn't want to guess even more than I am for the open loop 'switch'.

Thanks!

[wait4me]

well, turn the ses light off for code p0102 and turn it to non emmissions, but dont turn it off all the way, then copy over your high octain table to the low octain table. Set your maf fail rate to 0. or just dissconnect your maf sensor after dissabling the 102 code... then to dissable the closed loop enable, {B3801} Long Term Fuel Trim Correction turn to off.

[SinisterSS]

Disable power enrichment to more easily track your commanded A:F to PLX actual.

Whitney, are you using a wide-band?

[AllCammedUp]

Cool Jesse and Rick - this helps out a lot!!

Yes, I've got a PLX-300 permanently mounted in the car, so I can see and log my AFR at all times.

How does disabling PE help track commanded AFR? Isn't tracking commanded AFR via a PID sufficient? Also, with PE disabled, I take it I should NOT attempt to get the car into PE, correct?

Please bear with me, I'm learning this as I go. ;)

Thanks to both of you guys - I really do appreciate it!

[SinisterSS]

With PE mode on, it will dump extra fuel in during acceleration. This extra momentary fuel "polutes" your A:F values in the PLX map.

Another alternative is to leave PE on and set your PE A:F the same as your commanded A:F.

With PE off or set to the same as commanded, you can run hard and not screw up your map. It is good to get the PLX readings in the high MAP values (normal PE areas) to validate your VE table.

[AllCammedUp]

With PE mode on, it will dump extra fuel in during acceleration. This extra momentary fuel "polutes" your A:F values in the PLX map.

Another alternative is to leave PE on and set your PE A:F the same as your commanded A:F.

With PE off or set to the same as commanded, you can run hard and not screw up your map. It is good to get the PLX readings in the high MAP values (normal PE areas) to validate your VE table.

Oh, OK. I see what you're saying in regards to 'polluting' the map - that does make sense.

That, however, leads me to the next question(s):

What is the best way to turn off PE?
What is the best way to set the commanded AFR under varying conditions?

I understand that I'd change the PE AFR via the PE/RPM table, but I'm not sure where I match those values up to the commanded AFR other than what the scan tool shows me via the commanded AFR PID.

[SinisterSS]

There are many ways to do it.

Engine Calibration -> Fuel -> Mixture -> Parameters

Maximum Enrichment = 13.0:1
Delay before Entering PE Mode = 410 seconds
PE MAP Threshold = 105 kPa

Engine Calibration -> Fuel -> Mixture

PE Modifier Based on RPM - set all to 13.0
PE Modifier Based on Coolant Temp = 0
PE Modifier Baed on Intake Temp = 0

To pick your commanded A:F, set all the cells to 13.0 in

Engine Calibration -> Fuel -> Mixture -> EQ Ratio When in Open Loop

Once you've tweaked your VE table and commanded is fairly close to your actual and you are no longer scared of a lean melt down, you could change your PE and commanded A:Fs from 13.0 to 14.7 or any other value you wish.

[SinisterSS]

Disclaimer: I may have missed something - it's late and I'm tired. :?

When logging the commanded AFR map, you'll know quickly if you missed something in PE that is screwing up your ratios.

[AllCammedUp]

OK Rick, I see. Thanks much for the insight. I wanted to make sure I knew which parameters to change and to what so that I didn't go messing around and tear up something I've got so many $$ invested in. I feel safer just knowing what to change (and what to change back ;)) in order to accomplish the goal.

[Blacky]

Ross and I were discussing this the other day:

If you are happy to drive around with a flat AFR of say, 13:1 then try using bidirectional controls to command the AFR to 13:1 which effectively turns of all PCM fuel control. (You can use whatever AFR you like).

I don't think it is necessary to set the Open loop bidi control or the Fuel learn bidi control because you are forcing 13:1 ALL the time. The PCM will use the VE table to try and figure out the correct pulse width to achieve 13:1 and whatever error you see in the BEN PID will be the amount your VE table is "out".

As soon as you switch off the ignition, bidi conrols are terminated and it is "back to normal". But you'll still have your map for auto updating your VE.

I have not tried it, I do not know if that will work, but I thought I might throw it the thread for discussion.

Regards
Paul

[AllCammedUp]

Ross and I were discussing this the other day:

If you are happy to drive around with a flat AFR of say, 13:1 then try using bidirectional controls to command the AFR to 13:1 which effectively turns of all PCM fuel control. (You can use whatever AFR you like).

I don't think it is necessary to set the Open loop bidi control or the Fuel learn bidi control because you are forcing 13:1 ALL the time. The PCM will use the VE table to try and figure out the correct pulse width to achieve 13:1 and whatever error you see in the BEN PID will be the amount your VE table is "out".

As soon as you switch off the ignition, bidi conrols are terminated and it is "back to normal". But you'll still have your map for auto updating your VE.

I have not tried it, I do not know if that will work, but I thought I might throw it the thread for discussion.

Regards
Paul

Paul,

Good to know we have two options! I was considering this before I started the thread, but I've never heard anyone talk about it before, hence me starting the thread. I knew that you/Ross, Rick, Jesse, Steve B., John S., Brains, Delco, etc. al. have obviously done a good bit of this work, so I wanted to see how the 'people in the know' were going about it.

I like the bi-di control approach 'better' because I don't have to maintain an 'open-loop' version of a specific TUN. Anyone else tried it this way?

[GMPX]

I am actually going to venture out of the house tommorrow and plan on logging as discussed above. Hopefully I might have something to report back.

Cheers,
Ross

[Bruce Melton]

I am actually going to venture out of the house tommorrow and plan on logging as discussed above. Hopefully I might have something to report back.

Cheers,
Ross

I hope you make it back! :roll:

[SinisterSS]

With Bi-Di active, I've never been able to log data at the same time.

Obviously I'm not patting my head while rubbing my tummy in the right way... :?:

[Tydriver]

Ross and I were discussing this the other day:

If you are happy to drive around with a flat AFR of say, 13:1 then try using bidirectional controls to command the AFR to 13:1 which effectively turns of all PCM fuel control. (You can use whatever AFR you like).

I don't think it is necessary to set the Open loop bidi control or the Fuel learn bidi control because you are forcing 13:1 ALL the time. The PCM will use the VE table to try and figure out the correct pulse width to achieve 13:1 and whatever error you see in the BEN PID will be the amount your VE table is "out".

As soon as you switch off the ignition, bidi conrols are terminated and it is "back to normal". But you'll still have your map for auto updating your VE.

I have not tried it, I do not know if that will work, but I thought I might throw it the thread for discussion.

Regards
Paul


Weird, I thought I already responded here, I musta not hit SUBMIT before closing the page.. Anyhow..

I got a chance to do this in my '02 5.3L Silverado.. I didnt go to a 13:1 AFR tho.. I went to 15.7-16.0:1 just to see what it would do.. I suspect that there is some sort of protection feature active in the PCM tho.. The truck was seriously down on power when I was driving it.. Heck, it wouldnt even turn over the tires from a stop sign..

With that said, I did a couple of WOT blasts and I didnt notice any KNOCK, so I think it must also retard the timing a bit as well.. You can watch it drop off as the RPMs come up, I never saw over 19.5-20.0* of total advance under WOT(remember tho, I was watching the road primarily)... I did a couple of runs with where I re-enabled the stock PCM controls (shut off Bi-Di controls while I was going WOT) and there was a sizeable increase in the SOTP (Seat of the pants) dyno. The truck pulled harder and quicker to redline with it disabled during the run..

Just some additional food for thought, it must pull timing as well.. In any other event other than WOT, it was almost completely un-noticeable while driving however...

I may try this on my next road trip to see if it can be an INTERIM version of LEAN CRUISE while we await the COMMERCIAL version and overseas OS's so we can utilize it here in the US..

I saved a couple of logs if anyone is interested in them let me know.. I barely know what I am looking at since I am still NEW to this stuff !

[Blacky]

With Bi-Di active, I've never been able to log data at the same time.

Obviously I'm not patting my head while rubbing my tummy in the right way... :?:

If you start logging in 10fps mode then EFILive prevents you from opening the bidi window.
If you start logging in Dynamic mode then EFILive allows the bidi window to be opened.
If you have the bidi window open, then start logging in 10fps mode, EFILive drops logging speed to dynamic.

Regards
Paul

[Tordne]

I've just logged a couple of runs using the Bidirectional Controls to set the AFR to 13.0:1. It works really well, and if I understand correctly it shortcuts having to tune out all the other aspects/functions of the calibration which affect and/or interfere with the final commanded AFR.

Very happy with that solution, thanks Paul/Ross.

[daveb]

Sorry for the late response.

I do not understand why you would want to disable PE mode.

When tracking commmanded AFR and logging AFR from a WBO2 sensor (eg PLX300 - which is what I use) we can log the difference between the two and adjust the fuel maps accordingly. They are not really polluted because we are not aiming for stoich anymore and the commanded AFR value indicates by how much we are deviating from the base values.

Running too lean at WOT would be risky, particularly if the MAPs are wrong and you run lean. So I would have thought running WOT with the leaniest mixture (ie no PE enrichment) would be the LAST thing you would want to do. Better to start rich and work lean to get the optiminal power output.