Just tuned a 1997 A4 Camaro.

Used an M6 OBD1 Computer. (I'm pretty sure this doesn't make a difference but thought I should mention it anyways).

It shifts fine through 3 gears... but will not shift into 4th. The Datamaster logging indicates that the computer is "Telling" the tranny to shift, but it doesn't. I've tried two "Stock" programs... but still no go.

With the OBD2 computer... the car shifts into 4th gear with no problems.

The Camaro is a heavily modified/supercharged... and runs great otherwise.

Strange problem.... anyone know what it could be?

 

Obd 2 cars had PWM (pulse width modulation) for torque converter lock up. You need the tranny data imported into the obd1 tune from the obd2 to make it all work.

 

Thanks for the quick reply.

Where would I get that information from? I only have TunerCat to read OBDI

I originally disabled the TC lock-up and it still didn't shift. Would that make any difference?

 

Did you turn on the "automatic transmission" option in TunerCats ECM switch table?

 

Yup... it shifts from 1-2 & 2-3 fine.

I see it signalling to hit 4th gear.... but it doesn't actually shift to that gear.

 

I have a obd2-1 conversion tune for an A4 on a hard drive somewhere. Give me your email and I'll send it your way. You can "compare" to what you have now.

 

PM Sent.

Thanks in advance.

 

I think I figured it out.

The PCM is from a 1994 Camaro. It seems that the 94's didn't have PWM...and so while a 95 PCM will work for a 97 Auto... a 94 will not, even with the proper tune.

Just thought I'd follow up since others may use this post as a reference.

 

I dont think it will matter what year it is out of the pcm's are all the same part number for obd1 except 1993 if I am not mistaken. The fact that it does not have pulse width modulation of the torque converter should not matter as it will just command 100% duty cycle to the converter clutch rather than pulsing it in to keep it from making a sudden jerk.

Take a good look over your shift tables and your lockup tables and make sure nothing is screwy there. It would also be a poor electrical connection to the transmission, maybe one of the pins is knocked off the pcm or something like that or a trace on the pcm is bad.