Car wont run after pcm change

I took my zzp pcm out and went back to stock. The car ran fine, so I sold the zzp pcm, and when I left the post office my car wouldnt run. It will start for a second but dies. I did get it to run for about a minute with the pedal floored but that only happened once. Mostly it just wont start, or starts and dies immediately.
When I took off the pcm, I also removed a zzp voltage booster, and an alternator power rewire. Everything was fine driving around town making a few stops, but now it wont start.
Do you think the stock pcm is bad? Or maybe I need to reinstal the pcm? I did unplug the battery and took the plugs off the pcm and reinstalled them, but still no start.

Are you using a different key?

Just a guess, maybe your fuel pump resistor went bad:

No, its the same key. And I tried the relay trick too. I'm not sure what's going on. I just hope I get it figured out soon so I don't have to tow it.

Here's the security relearn procedure from ZZP's site:

1. Disconnect battery

2. Install new computer

3. Reconnect battery

4. Put emergency brake on to disable daytime running lights (this step is required!)

5. Make sure all doors trunk and hood are closed leave driver window down and reach in threw window

6. Try to start. If it doesn't start, leave the key in the on position for 10 min on 97-03 cars and 15 min for 04 and newer cars. The security light should turn off after this amount of time.

7. Turn off ignition for 3 seconds

8. Try and start the car. It probably won't start. Repeat step 5 two more times.

9. If this doesn't work disconnect battery for 5 seconds and then try and start the car.



If that doesn’t work, try this one:



1. Disconnect battery for 10 sec.
2. Reconnect battery
3. Turn key to ON position
4. Do not try to start vehicle, just quickly click to RUN position to engage security light
5. Let vehicle sit with key ON for 35 min.
6. Attempt to crank vehicle. Once vehicle is running, the security light may still be on
7. If security light is still on, turn key to OFF position for 5 sec.
8. Turn key to ON position and security light should turn off
9. Start vehicle and enjoy new PCM

Notes: If your car starts at any time and stays running, you are done. If your car starts and dies, try step 9. If it dies after 2 seconds after you have done these steps, you either have a bad FP resistor or the security setting in your PCM is wrong and it will need an update. Security relearn procedure will not work with the valet key!

Hope this helps!

Thanks for taking the time to help me out on this one. I have actually been going through that same list off of the zzp site. So far I'm 25 minutes into the last step 5, so I'll let you guys know in about 10 minutes if it works.
Thanks again

Nope. Still no luck

Did you try starting it with the MAF sensor unplugged?

Yeah, I tried that too. I towed it lastnight, so I guess that gives me more time to figure this out, but I'm pretty well stumped here.

Ok, now I'm really confused. I just went out to start working on it today, and it started right up!

Somehow that doesn't surprise me.. My car acted up last year at an all Pontiac show, when it was time to leave. Twice it cranked over and wouldn't run, third time it caught and ran, but the starter drive gear wouldn't disengage from the flywheel. Started up normally on the fourth try, so I drove it home and replaced the starter. Ran fine for about 75 miles before acting up again. Turned out to be a faulty fuel pump relay.
Gremlins always seem to show up in pairs, or groups of three with our cars..

Hey, would you recommend a PCM or are they more troble than they are worth? Where would I buy or order one? I'm looking at giving "new Life" to my 2000 GTP and I thought a high performance PCM might do the trick. I'm not planning on doing any racing. Thanks, VCH

You're better of getting a dyno-tune done instead. If you don't have a dyno-tuning joint anywhere near, find a tuner, wideband O2, and someone with experience to help you tune on the street. Those off-the-shelf tunes will help you get close to what mods you have, but a custom tune is where it's at!

After about a week of working fine, its dead again. I can't figure this out at all. It cranks, but wont start.

Check to see if it's a no spark or no fuel condition. Intermittent no start problems are the worst to track down, especially when it was a customer's car, and he's hovering over your shoulder..

If I depress the pin on the schrader valve on the fuel rail while someone trys to start the car, I get no fuel comeing out, so I'm assuming its a no fuel issue

That's what my GT did when the fuel pump relay acted up. It would click to prime the pump, but had no fuel when cranking over. I swapped the old relay I kept as a spare, and the car fired right up. So I always keep extra fuel pump relays in the glove box.

Here's a '98 GTP wiring diagram, hope it helps:

Thanks. I have to go work on my in-laws roof, so I'll get back to the car tonight

I finally got a minute to do some work, and it looks like I will be purchasing a new fuel pump. This is the first time I've seen one that didn't just die outright, the intermittent nature of this really threw me off.

Got the pump in last night and the car ran great. I ran a few errands, and had no problems at all. This morning I got in the car and it wont start. This is really starting to drive me nuts