96 vs 98 PCM car wont start!

I put in the 98 pcm into my riv to test it for the trans swap I have coming up.

I put in the 98, and the car wouldn't start. Put in 96 back in and it still wont start!

My mechanic thinks its an issue with the security VAT system. I bypassed security in my powertuner (I think) and the car still wont start up. Its getting fuel and spark. The plugs were dry so our theory of flooding the motor is out the door too.

It did something similar after the new injectors, but I checked the tune and the setting for my 42lb injectors are still in the bin.

what am I missing? why wont she start up?

no DTC's

dreww wrote:

Its getting fuel and spark.

If it's getting fuel and spark, it should run!

As I understand things, the '96 PCM and '98 PCM are not interchangeable without some rewiring. Hopefully you haven't damaged anything.

Try the 'brake cleaner trick' - take the vacuum line off from under the supercharger snout, hook a hose up to it and spray brake cleaner into the hose. Modulating the spray, you should be able to keep it running. If you can get it to run like this, your spark is okay and fuel is your problem. You should be able to keep it running like this for a while, I think I ran my car for 30 seconds or so like this.

IIRC if the VATS is pissed off, your fuel pump won't run. You can 'jump' the fuel pump by removing the relay and using a jumper wire across the appropriate terminals under the back seat.

Its not the fuel pump, you can hear it running. Im not real familiar with how the security system works.....could it be a VATS problem in your opinion?

and we checked the fuses, all of them (engine bay, panel and under rear seats)

I think 98 you need to do a security learn. That is why I went with a 1997 PCM for my 4T65E conversion.

oldsman105 wrote:

I think 98 you need to do a security learn. That is why I went with a 1997 PCM for my 4T65E conversion.

gotta get someone with a TechII to put the car's VIN into the 'new' PCM - after that then do a CASE learn.

Albertj

please tell me your shitting me?! Not only do I NOT know anyone with a tech II, Ive never even seen one or heard of someone who has one.

so basically Im fucked with this PCM? its worthless to me

and why wont it start with the 96 pcm anymore?

how do you do a CASE learn?

DHP should be able to re-write vins and do a case learn. Try re-writing the vin in your 98 pcm to match your car.

dreww wrote:

please tell me your shitting me?! Not only do I NOT know anyone with a tech II, Ive never even seen one or heard of someone who has one.

so basically Im fucked with this PCM? its worthless to me

and why wont it start with the 96 pcm

anymore?

how do you do a CASE learn?

Every GM dealer has a Tech II

DHP should be able to re-write vins and do a case learn. Try re-writing the vin in your 98 pcm to match your car.

TonySmooth89 wrote:

DHP should be able to re-write vins and do a case learn. Try re-writing the vin in your 98 pcm to match your car.

Tony is correct.

I am not certain what amount of yelling or swearing will replace the VIN rewrite, but a little investigation probably would. Most major independent repair shops have ways to do it using various scan tools, and as I mentioned above Tony is correct.

You may have to rewrite the VIN in the '96 PCM; if I remember right it's something to do with the attempted PCM replacement. In the meantime you may find the following tutorial helpful:

http://www.hotrodlane.cc/ONLINETECH/computerrelearn.pdf

Albertj

Drew, have you asked these questions on the DHP forums?

dreww wrote:

please tell me your shitting me?! Not only do I NOT know anyone with a tech II, Ive never even seen one or heard of someone who has one.

so basically Im fucked with this PCM? its worthless to me

and why wont it start with the 96 pcm anymore?

how do you do a CASE learn?

You car is not starting with the 1996 PCM? You may have another problem on your hands. I think you should try to get your car running with the 96 PCM before you go back to the 98 PCM.

Like mentioned the 96 and 98 are wired differently. It is possible you blew out a sensor.

When you turn the key the fuel pump primes and the injectors fire a priming mist into the cylinders. The starter engages and spark is thrown. If vats is happy the injectors fire and the car runs. If Vats is tripped then the car runs for 2-5 seconds and stalls.

The main reason Oldsman chose the 97 pcm was because it had the 4T65 trans, SC motor and the wiring pinouts were the same as 96. Pinouts changed with the pcm in 98. That would have meant a new wiring harness or a lot of pin moving.

BillBoost37 wrote:

Like mentioned the 96 and 98 are wired differently. It is possible you blew out a sensor.

When you turn the key the fuel pump primes and the injectors fire a priming mist into the cylinders. The starter engages and spark is thrown. If vats is happy the injectors fire and the car runs. If Vats is tripped then the car runs for 2-5 seconds and stalls.

The main reason Oldsman chose the 97 pcm was because it had the 4T65 trans, SC motor and the wiring pinouts were the same as 96. Pinouts changed with the pcm in 98. That would have meant a new wiring harness or a lot of pin moving.

I apologize - did not knwo about the pinout changes. This may be big part of the problem.

Albertj

so....wish I had known that before I got that 98 bill.

So what sensor do you think it was? I did notice the pinouts seems different on the 98.

my friend says the injectors are not pulsing at startup.

guess i'll try the tech article link posted above