02 DBW A4 1st drive problems...
04-23-2009, 12:53 PM
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02 DBW A4 1st drive problems... Thanks to many on this board, I'm finally nearing the end of my resto-swap, but the first drive through the neighborhood could have gone better.
I'm not sure if I have a transmission problem or a swap/wiring problem, so maybe someone can help out.
hope the long post doesn't scare you off...
It's a 70 Chevelle with 02 Corvette LS1, Drive By Wire, with 4L60E setup, all stock at this point.
Motor seems to run good and loud (open headers for the moment, no O2 sensors). In neutral, revs fine. Reverse seems OK since it backs down the driveway fine. Put it in Drive (actually OD i suppose), it accelerates through 1st gear, then shifts and seems to just coast with the gas pedal pretty much dead. If I brake and/or just slow down so it goes back into 1st, the throttle responds again as normal. Can't take it out on the highway to get it to the muffler shop since only get power in 1st it seems.
I tried moving the shift lever into 3rd,2nd,1st...in 1st again seems OK. Other gears don't really seem to be there, or allow the motor to rev.
This motor and tranny were from different cars, so this setup has never previously worked together. The wiring harness was Camaro that I modified to use the Corvette DBW with TAC box. Only 3 cruise wires are left unhooked on the TAC for now. Pretty sure the wiring is OK, electrical circuits for me are no problem.
Only codes it throws are O2 sensors on handheld scanner. PCM was put back on hptuners and there was at some point a high trans temp recorded, so I removed the red and blue connectors from the PCM and ohmed out the trans temp sensor when it was cooled off, but it's an open circuit (is this normal?) Not sure how over temp could have occured...hasn't been more than 2 miles total. Would open temp sensor in tranny cause power train shutdown above 1st gear?
Any ideas? Could wiring mess this up? Seems if it were just trans the throttle wouldn't die. Did I neglect to hook up something critical?
Thanks!!
I'm not sure if I have a transmission problem or a swap/wiring problem, so maybe someone can help out.
hope the long post doesn't scare you off...
It's a 70 Chevelle with 02 Corvette LS1, Drive By Wire, with 4L60E setup, all stock at this point.
Motor seems to run good and loud (open headers for the moment, no O2 sensors). In neutral, revs fine. Reverse seems OK since it backs down the driveway fine. Put it in Drive (actually OD i suppose), it accelerates through 1st gear, then shifts and seems to just coast with the gas pedal pretty much dead. If I brake and/or just slow down so it goes back into 1st, the throttle responds again as normal. Can't take it out on the highway to get it to the muffler shop since only get power in 1st it seems.
I tried moving the shift lever into 3rd,2nd,1st...in 1st again seems OK. Other gears don't really seem to be there, or allow the motor to rev.
This motor and tranny were from different cars, so this setup has never previously worked together. The wiring harness was Camaro that I modified to use the Corvette DBW with TAC box. Only 3 cruise wires are left unhooked on the TAC for now. Pretty sure the wiring is OK, electrical circuits for me are no problem.
Only codes it throws are O2 sensors on handheld scanner. PCM was put back on hptuners and there was at some point a high trans temp recorded, so I removed the red and blue connectors from the PCM and ohmed out the trans temp sensor when it was cooled off, but it's an open circuit (is this normal?) Not sure how over temp could have occured...hasn't been more than 2 miles total. Would open temp sensor in tranny cause power train shutdown above 1st gear?
Any ideas? Could wiring mess this up? Seems if it were just trans the throttle wouldn't die. Did I neglect to hook up something critical?
Thanks!!
04-24-2009, 11:53 AM
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Good ideas Thanks, plus an update.
I think the PCM is getting good readings from both engine speed (because tach output wire on pin 10 works) and VSS (since electronic speedo works). I didn't see in the wiring diagram where these signals are applied to the tranny. Not sure how to confirm abuse mode. Scanner with live data mode?
Update. Found pins not locked in Transmission connector (strange since it was a pull-out), but now they are seated and I read normal resistance value on TFT pins at computer (about 3k with tranny at room temp). All other wires are connected to correct pins at computer also (according to the 02 vette schematic I have).
Also, I hooked up O2 sensors, and engine revs/releases noticeably better.
Now, I can force it up through the gears, i.e. I put in 1st, it goes into 1st and accelerates, force 2nd it goes in, and force 3rd goes into gear. BUT, in 2nd or 3rd, the throttle only will increase with -very- light application from 0...if I mash it down about half way, I can continue to mash it back and forth while the car is rolling and the engine does not respond at all. Let off pedal, apply very lightly, it will accelerate slowly. If it is in OD, first shift is hard and does not shift to 2nd...it seems to go to 3rd or 4th kind of bogging down with dead pedal syndrome, not shifting 1-2-3-4 like it's supposed to.
Isn't this usually a no-brainer type hookup, where if the tranny wires are connected the drivetrain pretty much just works? Guess not in this case.
With a TAC system, what would make it not respond? Just occurred to me that maybe gas pedal is defective, or fuel pressure is not good? I have the Walbro pump in an Impala tank with vette regulator, 3/8 plumbing. I'll have to check these both, but other ideas most welcome.
Thanks!!
I think the PCM is getting good readings from both engine speed (because tach output wire on pin 10 works) and VSS (since electronic speedo works). I didn't see in the wiring diagram where these signals are applied to the tranny. Not sure how to confirm abuse mode. Scanner with live data mode?
Update. Found pins not locked in Transmission connector (strange since it was a pull-out), but now they are seated and I read normal resistance value on TFT pins at computer (about 3k with tranny at room temp). All other wires are connected to correct pins at computer also (according to the 02 vette schematic I have).
Also, I hooked up O2 sensors, and engine revs/releases noticeably better.
Now, I can force it up through the gears, i.e. I put in 1st, it goes into 1st and accelerates, force 2nd it goes in, and force 3rd goes into gear. BUT, in 2nd or 3rd, the throttle only will increase with -very- light application from 0...if I mash it down about half way, I can continue to mash it back and forth while the car is rolling and the engine does not respond at all. Let off pedal, apply very lightly, it will accelerate slowly. If it is in OD, first shift is hard and does not shift to 2nd...it seems to go to 3rd or 4th kind of bogging down with dead pedal syndrome, not shifting 1-2-3-4 like it's supposed to.
Isn't this usually a no-brainer type hookup, where if the tranny wires are connected the drivetrain pretty much just works? Guess not in this case.
With a TAC system, what would make it not respond? Just occurred to me that maybe gas pedal is defective, or fuel pressure is not good? I have the Walbro pump in an Impala tank with vette regulator, 3/8 plumbing. I'll have to check these both, but other ideas most welcome.
Thanks!!
04-24-2009, 01:24 PM
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Computer has been reflashed with stock vette dbw, minus the usual stuff 2nd O2, etc. In neutral, engine seems fine, revs, etc and TAC seems to be talking to PCM fine, so I think program is good.
