3400 V6, 1999 vs. Later VCMs

[AleroB888]

This is a difficult problem to even explain, so please bear with me on this.

As I kept putting more performance mods on my car ('99 Alero V6), everyday drivability kept getting worse (no surprise there). In particular, the idle was not stable, especially on a hot start-up-- had to keep throttle open a bit till it got into gear. I was able to band-aid the problem by introducing a controlled vacuum leak just after the supercharger. A couple years ago, A friend reflashed a spare VCM with a copy of his stock 2001 Alero program. I put that in my '99, and got perfect drivability. But using the 2001 VCM has two glitches--the Charge warning light and chime come on because the alternator wiring is different in the '99. And I can't change the coolant fan settings in the '01 VCM, but I can with the '99.

Recently I added an intercooler and upped the boost, and the problem is more severe.
The worst symptom is, I'm at a stop, step on the gas, and you hear a little rush of air, and the engine stumbles or dies. The faster you hit the pedal, the quicker it dies. If I set the target idle to 800 rpm or more, I can drive the car, but it still has some hesitation and runs rough. I put the '01 VCM program back in, runs fine.

I have tried copying every engine and trans table from the '01 program to the '99 VCM with no luck. Would appreciate any help.

[Onyx Dragon]

This is a difficult problem to even explain, so please bear with me on this.

As I kept putting more performance mods on my car ('99 Alero V6), everyday drivability kept getting worse (no surprise there). In particular, the idle was not stable, especially on a hot start-up-- had to keep throttle open a bit till it got into gear. I was able to band-aid the problem by introducing a controlled vacuum leak just after the supercharger. A couple years ago, A friend reflashed a spare VCM with a copy of his stock 2001 Alero program. I put that in my '99, and got perfect drivability. But using the 2001 VCM has two glitches--the Charge warning light and chime come on because the alternator wiring is different in the '99. And I can't change the coolant fan settings in the '01 VCM, but I can with the '99.

Recently I added an intercooler and upped the boost, and the problem is more severe.
The worst symptom is, I'm at a stop, step on the gas, and you hear a little rush of air, and the engine stumbles or dies. The faster you hit the pedal, the quicker it dies. If I set the target idle to 800 rpm or more, I can drive the car, but it still has some hesitation and runs rough. I put the '01 VCM program back in, runs fine.

I have tried copying every engine and trans table from the '01 program to the '99 VCM with no luck. Would appreciate any help.

I don't know that this is a tuning issue so much as a problem with another part. Are you out flowing your maf? Your injectors (though this would likely net you knock more than stumbling)? Do you have a vaccum leak else where you don't know about? (that happened to me with my 04 GTP, btw) It's hard to determine what the problem is when you've added something like a supercharger, but you don't list everything you've changed with it. If your sig has everything you've changed, you may be missing some things. I don't know that the MAF of an alero can handle that, but I'm not that sure. It could be a million and one things to be honest. Did the problem start directly after the S/C? Did it start before it? Was there a particular part that influenced the problem more than others? I'd look at what the differences are in the 99 vs the 01 PCM for the Aleros. That might give you a bigger clue as to what you need to tune or modify in or on the engine.

[Turbo Alero]

maybe its you're maf.
ask on the the other websites like www.Nbodypower.com,
www.Aleromod.com or
60v6.com
They may help you

[devildog9999]

Any chance we can see a scan and your current HPT file?

I have seen this before in the Alero's and may be able to help you out.

[AleroB888]

I'm still working on this problem, but I need to take it one step at a time. Can anyone tell me if these tables are the correct Stock configurations for 1999 Alero/Grand Am V6 ?


The kPa scale starts at 20, but in the 2001 model there are columns for 10 and 0 kPa.
Also the VATS setting shows PWM for the 1999, but the 2001 model setting is Serial.
I read in another thread that some of the V6 tables were originally not set up right in the Editor software. Could that be the situation here? I have not downloaded the latest HP tuners version due to PC problems.

[MMGT1]

Attachment 9774

VE table for 01 stock Grand Am

What you have posted looks like a stock table for a 99, and with 2.0 you see what you have, no extra