97gtp stutter at hard throttle

[BNaylor]

Originally Posted by 97grprixgtp

I am using the throttle body and maf from the 99.

The MAF (Mass Air Flow) sensor for 1997-1998 is different from 1999 and up. Also, the MAF/VAF programming tables programmed in the PCM module is different so one issue is you have an incompatability issue.

Do you still have your original throttle body and MAF sensor?

[3100]

map should show outside barometric pressure withe key on engine off. It should also be about 4.7V then when engine is idling it will show 10 or 11 in Hg so you subtract from your barometric pressure for example : 30in Hg with key on engine off and when engine is idling you see 10 in Hg that means that your engine at idle is producing 20 in Hg of vacuum and that is normal. So at idle map should show about 1.3-1.5 V

[97grprixgtp]

Originally Posted by BNaylor

The MAF (Mass Air Flow) sensor for 1997-1998 is different from 1999 and up. Also, the MAF/VAF programming tables programmed in the PCM module is different so one issue is you have an incompatability issue.

Do you still have your original throttle body and MAF sensor?

No I do not still have the old stuff unfortunately. Do I need the throttle body? Or just the MAF?

[97grprixgtp]

Originally Posted by 3100

map should show outside barometric pressure withe key on engine off. It should also be about 4.7V then when engine is idling it will show 10 or 11 in Hg so you subtract from your barometric pressure for example : 30in Hg with key on engine off and when engine is idling you see 10 in Hg that means that your engine at idle is producing 20 in Hg of vacuum and that is normal. So at idle map should show about 1.3-1.5 V

And actually that is my reading at idle of 10in hyg.

[3100]

how many g/sec of air MAF is showing at idle? it should be between 3-5 g/sec

[3100]

if you experience the same problems with maf sensor disconnected, then maf is not your problem. With MAF sensor disconnected PCM takes over using its own mapping tables. You will still be able to drive, and the only problem you will notice is when ever you accelerate from complete stop engine will choke for 1/2 sec other than that it will run normal.

[97grprixgtp]

Originally Posted by 3100

how many g/sec of air MAF is showing at idle? it should be between 3-5 g/sec

The g/sec at idle is between 6 and 10. mostly around 6 to 7

[97grprixgtp]

I also show a lean mixture in the 12s at idle and seems to shoot to rich under load when it breaks up.

[97grprixgtp]

It does do it with the maf unplugged too.

[3100]

did you have this problem with the old engine? try removing serpentine belt for and test drive it for 2 min, sometimes rectifier bridge in the alternator can go bad and some AC voltage will pass unfiltered and that can cause problems that you have. Or put your old alternator on.

[97grprixgtp]

Did not have the prob prior. It is my original alt.

[3100]

can you do ckp relearn on your scanner?

[97grprixgtp]

No it does not seem to have the ability to do a case learn. I see the maf is smaller on the 97-98 so I guess i need the throttle body. Are they the same on the non sc as on the sc engine?

[97grprixgtp]

Ok picked up another throttle body and put it on last night, the stutter and miss is not as bad but is still there. Got in it this morning fired it up and at first it would not idle and the throttle was nearly unresponsive. Finally got it to idle but it is idling at 1800 rpm. And now my scanner will no longer read the car. It keeps saying to check the key is in the on position and I have no check engine light any longer. Any new help is greatly appreciated.
Thanks

[tblake]

Check your fuses for the cigarette lighter circuit on the scanner issue. Then you'll want to make sure all the Pins in your ALDL are lined up and not bent both in the car plug and your scanner.

The Crank Variation Learn as Bob (bnaylor) mentioned is not necessicary unless the code is present.

What year, make and model did the throttle body come from?

3100, just so you know, I was working on a 1998 olds intrigue with 3800. The car ran bad, random misses all over the place, and randomly stalled. Unplugging the MAF made the car run WORSE. Replacement of the MAF is what cured the problem. So sometimes unplugging it isn't a valid test.

Bob, do you think the knock sensors should have been transfirred over from the old motor the the new one?