Rough running after flash and return to stock, TPS problem?

[Whodunnit]

Oh no! :help2:

In my quest to fix my speedo I did a simple PCM flash. The car immediately ran poorly. I don't think I touched any parameters that should affect engine performance so I took a short drive to see if it got better. It didn't, so I flashed back to my previous stock config, but now the TB's running even worse! :confused:

It looks like the TPS value is spiking downward every couple seconds at idle, each time almost causing the TB to stall. Do you know what could be causing this? Faulty TPS? Need for adjustment or recalibration?

Thanks in advance for any help you can provide! :help2:

[Whodunnit]

ps. I'm not sure if it relates to this thread or not. Symptoms sound similar except problems just began after first flash.
http://forum.efilive.com/showthread.php?t=11193&highlight=tps

[Whodunnit]

One more piece of information I learned this morning. The cuts in rpm correspond with the A/C attempting to kick on. When I disable the A/C the idle goes smooth.

Now, what would this have to do with pulling my stock calibration, reprogramming w/ different speedo settings, and then reverting back to my stock cal data?!?:confused:

Is there a bug in the LL8 / FlashScan somewhere? I'm losing faith in EFI Live.:bad:

[joecar]

So you flashed your stock cal back and now there's a different problem...?

I would say do a full flash of your stock file, but I pm'd Tech Support, see what they say first.

[Whodunnit]

Thanks Joecar. To do a full flash, do you mean with the "use high speed" box un-checked, or are you referring to something else.
(my apologies for the noob-ish questions

[joecar]

There are two flash operations:
- calibration only ("cal-only flash") [narrow red down arrow],
- calibration and operating system ("full flash") [wide red down arrow];

I am wondering maybe your PCM may not have the full flash operation.

[Whodunnit]

I am wondering maybe your PCM may not have the full flash operation.

Gotcha. I'll have to check at the car, but here at my desk the full flash button is grayed out. Not sure what that means...

Do I need to worry about OS's matching? I suppose so, but not sure how to check or fix that if not. I read a few things about that but naturally am a bit lost. I'll keep digging...
:fluffy:

[Blacky]

When you read and/or re-flash your PCM the data is protected from accidental changes on many different levels. It is virtually impossible to have faulty/different data programmed into the PCM without causing an engine no start condition.

So if, after you re-flash your vehicle the engine fires and runs for more than about 1 minute then the data in the PCM is guaranteed.

There are a number of learned values that the PCM keeps stored in its volatile memory, such data is lost when you read or re-flash your PCM (or just remove/restore battery power to the PCM). That type of data includes the long and short term fuel trims and learned air flow adjustments. It can take a number of days and/or many miles of driving for those parameters to be re-learned correctly.

Adjusting the base/default values for that learned data will mean the values do not have to be learned very far from their original defaults, which means there will not be a large performance degradation (that needs to be learned out of the system) each time you read or re-flash the PCM.

As to which values need to be changed and by how much and in what direction is not something on which I can offer any useful advice.

Regards
Paul

[Whodunnit]

Brilliant! Thanks Paul. I have at least a few ideas of defaults that perhaps need to be adjusted... My 0%pedal is corresponding to ~15%TPS. I guess I just need to figure out where to make these changes and go from there!

I've updated my FlashScan to FW:2.06.12 and 2.06.02, but I still can't do a full-flash with my 12579357 OS (it's grayed out). Does anyone have a stock file for a 2003 Trailblazer (LTZ, not extended cab though)?... I'm wondering if that's the problem with the lack of full-flash .

Thanks again guys for your quick help with this!!!

[Blacky]

EFILive does not support full flashing for the 4.2 TB.

Since you've never done a full flash then doing one would not "restore" anything to stock because you won't have changed anything that a full flash would have changed in the first place.

Regards
Paul

[Whodunnit]

EFILive does not support full flashing for the 4.2 TB.


:master:Ah, I see... Thanks for the clarification.

I guess I'm back to troubleshooting my bad defaults. Any ideas of where to find them?:nixweiss:

[Whodunnit]

Adjusting the base/default values for that learned data will mean the values do not have to be learned very far from their original defaults, which means there will not be a large performance degradation (that needs to be learned out of the system) each time you read or re-flash the PCM.


Any tips on where to find these default values???:lookaround: Would performing a GM OBD-II Driving Cycle complete the learning process? (though I don't think I can, my TB won't even idle with the A/C running!)

I have to get the car smogged next week and I'm getting a little nervous about having it running smooth again like it was before the flashes.

[Chevy366]

One more piece of information I learned this morning. The cuts in rpm correspond with the A/C attempting to kick on. When I disable the A/C the idle goes smooth.

Now, what would this have to do with pulling my stock calibration, reprogramming w/ different speedo settings, and then reverting back to my stock cal data?!?:confused:

Is there a bug in the LL8 / FlashScan somewhere? I'm losing faith in EFI Live.:bad:

My wifes TB did this same thing because of the EVAP solenoid valve , bad idle with A/C (surging) , but I got a MIL and DTC P0449 .

[Chevy366]

Any tips on where to find these default values???:lookaround: Would performing a GM OBD-II Driving Cycle complete the learning process? (though I don't think I can, my TB won't even idle with the A/C running!)

I have to get the car smogged next week and I'm getting a little nervous about having it running smooth again like it was before the flashes.

Hook up the V2 and run Scan Tool and when connected open the SRT tab , the SRT will show what has "passed" or "not ready" , this is what most Emission Tests look at for passing .

[Whodunnit]

I'll try that. Thank you!

[Whodunnit]

A little followup and good news. Shortly after starting my next scan (after reading the above email) I decided to just drive the TB with the A/C on and keep the RPM's up to keep it running. After about 10 minutes the TB all of a sudden started running more smoothly and idled fine both with and without the A/C on. I guess it just took longer than I had thought to satisfy all the necessary OBD drive cycle parameters and (sufficiently?) complete the self-tuning process, and it didn't need to be idling to do it.
:cucumber:

I still show an EVAP "not ready" status in my SRT tab but decided to take the car in for the Smog Check anyway. It blew 00's and passed the CA emissions test with flying colors! (note, having the 4x4 option, the computer designated only the off-dyno test :rockon:)

Thanks for everyone's help with this. Now I can finally play with the settings and deal with the learn times with more peace of mind.

Peace! :cheers: