Thread: Replaced PCM, Regal now dies after running a few seconds

So I bricked the original PCM in the regal, started with a partial write, got an error message, tried doing a full write to fix it with no luck. So I got the numbers off the pcm, and grabbed a suitable replacement off ebay. Install the PCM, reinstall all my powrtuner stuff on the laptop (1.1 framework, 1.2.4, etc), connect the laptop up and I'm able to do a full write no problem. Wrote the same file I'd been using (did a read on the original PCM, and made all my modifications to that file) that I've never had any issues with, and now the car dies after about 3 seconds. Starts right back up every time, and dies again. Tried writing a '98 GTP file, but that was a no-go (wouldn't even crank). Not the fp resistor (I checked it just in case, though I found it hard to believe it would go bad just sitting for a few days waiting for the new PCM to arrive, both by bypassing it and plugging another resistor in).

Mechanically, no issues with the car, I'm sure this is somehow PCM or file related, or maybe security related. I tried doing the vats relearn procedure with no luck, resetting the passlock with no luck, writing an original '98 GS file from Bill's dropbox with only the IFR/injector skew changed for the 42's and E85, and nothing. am I missing here? I've gone through the file I've been using forever, found nothing off, disabled VTD, disabled flash security, re-enabled both after disabling had no effect. I replaced the PCM in my 'bonne (and running a '98 .bin on a '99 even), and had none of these problems, started right up. Is there something I don't know about the Buick security system that's doing this? I thought the VATS stopped it from cranking, not killing the fuel after it was already running. Thanks in advance for any suggestions.

sounds liek the high speed fuel pump resistor took a dump on you. check the fuel pressure after it stalls. if you got nothing its the resistor.


try this out. it should work on a regal too.

Yeah that was the first thing I did, bypassed it. Still didn't work, then I plugged in a spare one I had, same result. None of this started until changing the PCM, not sure if the PCM itself is part of the security system and the new one isn't being recognized or what. Changing it to single speed pump in the pcm via TT didn't work, either, figured I'd give that a shot since I'd tried everything else.

see if your getting fuel pressure tho.

when you have a security issue with a regal, it flat out wont crank, dead key when turned to crank. yours is running then stalling, like its out of gas.

For sure not a fuel issue, put a jumper wire from 30 to 87 (12v directly to pump) and still does the same exact thing. Pump never stopped pumping, strong gush out the schrader port of the rail. Guess I'll try and pull pinouts of the two PCM's and see if there are any differences.

thats odd.

Yeah it is, I'm thinking maybe there's a small difference between the wiring from the regal and the pins on the PCM.

This is the new one I got off ebay:

And my original:

Is this a security/passlock learn thing maybe? Sounds identical to what my truck was doing when I had the battery unhooked for a few days.

Just for giggles, try turning key to run for 15 minutes (without starting), then off, then run for 15 minutes, then off, and then try to start.

the pcm is the same part #, thats not the issue. ive used a gtp pcm from a 01 on my 98 regal, it works just fine.

this sounds like one of the sensors is not sending a signal to the pcm.

2004L67, I tried the relearn deal, no luck. The one I did was a little different (11 minutes between cranks), so it couldn't hurt to try the 15 minutes, will try after work. Eric, for the few seconds it runs, it runs great. I had the scanner hooked up, 02's were good, maf, timing, map kpa, nothing looked off. Dies at any rpm or tp%, too, tried revving it to keep it from stalling, no dice. I got a couple other ideas before I start comparing wiring pinouts between a 98 3.1 century and 98 gs, hopefully it'll pan out before I have to go that route.

Sounds like you narrowed it down to fuel.

I have seen a MAF do this, unplug it and try to fire it up. I'm thinking it's something silly, but in the settings. Unplugging will revert to some table and it'll run longer if it's something to do with the maf.

Unplugging the MAF was the next step I took after bypassing/testing the resistor. I was gonna unplug the 02 sensor too, but it was reading/switching normal on the scanner so I didn't bother. I'm gonna mess with a few different VTD relearn procedures and see if one works, when/if one does work, I'll be sure and post which one so anyone searching this 5 years later can save some time, lol.

Did you unplug anything else in the process? I know when I disconnected my transmission harness and started it, it will run for a few seconds and shut off every time. Plug the trans back in and it stays running.

Didn't unplug anything else, and definitely didn't try starting it before reflashing. It was out of a 3100 Malibu or something so it definitely wouldn't have worked. Gonna try all the steps listed on zzp's site under pcm replacement, then if that doesn't work I'll enable VTD in the file and run them all again and see what happens. One of them has to work, I'm 100% sure it's either security related, or its a bad pcm (got another one on the way, I'll just use it as a spare if I get it running with this one). Didn't get to work on it at all yesterday due to sister in laws wedding, got a few things to do today as well, wife always trying to keep me from getting **** done.

Well, simple and stupid just like I thought. Took my tuned file, changed all the security setting to stock (what the values read on the "stock data" tab), loaded it up and now runs just like normal. No relearn required, nothing. Which is kind of odd because I loaded a 100% stock file up before and it wouldn't run.

So anyone searching this in the future, if you changed your pcm and now the car runs for a few seconds and dies (and you've already verified your fp resistor is good, maf, etc), pull up the file you were using before changing the pcm, pull up your security (under diagnostics as well, there's 2 different security tables) and change them all to the values in the stock data tab on the right (flash security, checksum, etc). Save yourself a lot of time and sweat, lol.

when you loaded up a stock bin, was it the same osid#? if you open the bin in dhp in general the top line in the window of the bin file, it will tell you the osid#.

Yeah, OSID was the same for every file I tried, 9352797. Well, except the one '98 GTP file I tried, but that one it wouldn't even crank, just did that as a test to see what happened. Manually inserted the VIN each time in all caps, too (now I have 2 VINs memorized).

EDIT: Other VIN I have memorized is from my '97 GT that I had to enter the VIN manually a bunch of times for some reason, and that was like 10 years ago. 1G2WP12K9VF259900, got that memorized, but half the time I don't know what day it is.