Need some help from the EFI Live Community. Paul, Ross, Joe?

[finishline]

Background: the power plant and tranny is out of a 2007 Chevy Impala SS. That’s a E67 ECM for the 5.3 Liter LS4. The tranny is the 4 speed auto with the T42 TCM. All of this has been implanted into an 88 Pontiac Fiero GT. Car drives amazingly well except for one thing. Every time you floor the car and the wheels break loose the electronic throttle gets pulled all the way back to idle (20%). As soon as the wheels gain traction again the throttle goes back to wide open (88%) again. We never lift our foot off the accelerator pedal. This happens about 3 times and by then we’re going fast enough that the wheels won’t break loose again. The torque feels like it is applied to both wheels evenly. We don’t have any wheel speed sensors, no traction control and no BCM computer. The rev limiter on this car is via electronic throttle from the factory. I’ve turned that off along with all the traction control stuff and the torque management stuff. I’m stumped and can’t figure out why the throttle is being pulled.

Any suggestions will be fully explored on this end and everyone’s help would be greatly appreciated. I’ll update the community with our progress and findings. Logs and tune files are attached. Thanks in advance.

[swingtan]

Try maxing out the values in B2517 and see if that helps. It seems strange that you're getting this as you have already disabled pretty much ever other TCS setting. 0-60mph in 5.3 is not a bad effort though......

[finishline]

Thanks for your time and the reply. I have already doubled the numbers in that table but, I'm desperate and willing to try anything. I'll max that table and get back with the results. We are getting hit with 4-6 inches of snow tomorrow so it will be a couple days before I can get back with results.

Anyone else have some ideas? I'm all ears.

[gmh308]

Have you set the BCM and ABS DTC's in the TCM to not reported? Anything else there that is not applicable?

EDIT....Just saw your TCM cal. ABS and BCM are still enabled.

mmmmm...you have a 4L65E where a 4T65E was right? And a 5.3 front wheel drive engine/ECM in a longitudinal powertrain with the 4L65E. Interesting project. It will haul once the throttle starts behaving right .

[joecar]

This is way over my head...

Questions:
- swingtan/Simon: can he set B2503 to max(200)...?
- gmh308/Ian: which table/parameter id's in the TCM regarding ABS/BCM...?
- finishline: I noticed your gear ratios are those for the 4T65E, is this correct...?
- finishline: are any DTC's thrown...?
- what about tables C0803-6...?

[gmh308]

This is way over my head...

Questions:
- swingtan/Simon: can he set B2503 to max(200)...?
- gmh308/Ian: which table/parameter id's in the TCM regarding ABS/BCM...?
- finishline: I noticed your gear ratios are those for the 4T65E, is this correct...?
- finishline: are any DTC's thrown...?
- what about tables C0803-6...?

Hi Joe, great point on the ratios.

4T65E:

{D7001} 1st Gear Ratio 2.921020 Ratio
{D7002} 2nd Gear Ratio 1.567993 Ratio
{D7003} 3rd Gear Ratio 1.000000 Ratio
{D7004} 4th Gear Ratio 0.704956 Ratio
{D7006} Rev Gear Ratio 2.384765 Ratio

4L65E:

{D7001} 1st Gear Ratio 3.058960 Ratio
{D7002} 2nd Gear Ratio 1.625000 Ratio
{D7003} 3rd Gear Ratio 1.000000 Ratio
{D7004} 4th Gear Ratio 0.696045 Ratio
{D7005} 5th Gear Ratio 0.000000 Ratio
{D7006} Rev Gear Ratio 2.293945 Ratio


And...re the BCM and ABS - the DTC's:

U2105 "Lost CAN Communications With Engine Control System" B: 2 Trips, Emissions Related .
U2107 "Lost CAN Communications With Body Control System" C: Non Emissions .
U2108 "Lost CAN Communications With ABS/TCS Control System" C: Non Emissions .
U2139 "Lost CAN Communications With Body Control (CIM) System" X: Not Reported .
U2144 "Lost CAN Communications With Powertrain Control (ACC) System" X: Not Reported .

[swingtan]

B2503: Delivered torque upper duty cycle. You can set this to max, but I wouldn't, Id only take it as far as 199. This is so you can then set B2506: TCS active upper limit to 199 and B2508: TCS fault upperlimit to 200.


I'm not sure what the E67 will do if it thinks the TCS system has failed. It could just give up and disable all TCS / Abuse management attempts which would be good. Or it may go into "limp home" mode which is bad.

Given that all the TCS settings appear to be disabled correctly in the tune, I'd be tempted to try failing the TCS to see what happens. To do this I'd set B2508 to something really low, maybe 0 even. Then very carefully test it out. A good dump of snow will help here as wheel spin should be easily achieved.

Also, log the following pids to see what is going on....

ETCTP and APP

This will allow you to see the difference between what is happening at the pedal, and what is happening at the throttle blade.

Simon.

[gmh308]

Noticed that B2501 has been maxed. We have seen issues with taking this away from the stock number, especially with auto trans.

Normally once the TCS options have been set to "No", the traction control sleeps and does not wake up, but B0517 and B2514 are good for keeping wheelspin under control in lower gears . Simplistic launch control.

[joecar]

If the ratios don't match the actual trans gearset, will the TCM get upset about it...?

The TIS:TOS ratios will be diffferent from what the TCM expects... what will the TCM do in this case...?

[finishline]

The complete drive line is from the 07 Impalla SS, including the wiring harness, TCM and the ECM. Notice the vin numbers are all the same. I assume the gear ratio's are correct. The car does shift where it's supposed to. I tried some other things you can't see in the files I posted. Since they didn't fix the problem I put them back to stock. The file I posted is the one we are running on right now. I will try everything that has been suggested as soon as the weather clears.

On another note, the car comes with a traction control button just like the corvettes I usually work on. I wonder which wire that signal comes in on the E67 ECM and if it's just a ground signal? Anybody know?

Thanks everyone for the compliments. Actually this is only the third engine swap like this in the U.S. and it was my customers idea not mine. He did a ton of research and it was a very smooth swap except for this throttle blade issue. He does plan to drive the wheels off this thing after we get all the little bugs worked out.

Thanks for the suggestions and please keep them coming.