Our Community is 940,000 Strong. Join Us.


Engine cuts out when you hit the gas hard, but not when lightly accelerating


chriseisenbraun9
03-18-2011, 12:54 AM
I bought this van about a month ago. Motor was knocking, previous owner drove the thing for months having to dump multiple gallons of antifreeze in it per week, so i didnt want to rebuild the whole motor and my mechanic that I use for jobs to big for me said he had a 3.1L out of the same year grand am. motor came out of a friend of mines car and ran perfect after the car was wrecked. Anyway i had the motor put in my van for a total of $700. it starts up and idles perfect and runs fine if you accelerate very lightly, but as soon as you press the pedal harder the motor cuts out and starts horribly misfiring. you could be at 3k rpm and push it in harder and it will immediately drop below 1000rpm and the check engine light comes on. i have a code scanner and only code is a random misfire

Ive only put about 10 miles on it since i want to get it fixed before driving it much. I disconnected the MAF and it is a LOT better but still does it. Plus the engine light comes on for the maf right away when i disconnect it. I brought the maf inside and cleaned it with carb cleaner and let it dry overnight and it made no difference could i need to change the MAF to the one for a 3.1L?? or do i need to drive it some so the computer need to relearn the motor?

chriseisenbraun9
03-18-2011, 12:15 PM
little update i took it for a 20 mile or so drive and it runs ok now up to half throttle but anything over that and it starts misfiring like crazy.. and now im getting a check engine light for the MAF low input..

Moppie
03-18-2011, 04:42 PM
Sounds like it's missing under load?

Did you check the ignition system on the motor before fitting it?
It may be grounding under load, or the coil may have failed.

chriseisenbraun9
03-18-2011, 08:03 PM
Sounds like it's missing under load?

Did you check the ignition system on the motor before fitting it?
It may be grounding under load, or the coil may have failed.


Actually i figured it out, i bought a new mass airflow sensor today and swapped it and it runs perfect, Its amazing how just a sensor on the intake can make it misfire so horribly. Anyway if anyone else has an issue like this try the MAF, not cheap but if its not the problem you can always return it,

Moppie
03-18-2011, 08:14 PM
Sweet!
Glad you got it working again. It's always a nice feeling to figure it out and get a car going again :)

LMP
03-26-2011, 07:37 AM
What year is that 3.1?....the original..and the replacement...cause early 3.1 TBI and even MFI did not have a MAF (mass air flow)....they had a MAP (manifold pressure ). MAF was the exclusive of the 3.8

merc81
03-30-2011, 01:45 PM
'99 and up would have both a MAP and a MAF sensor. . .

LMP
04-02-2011, 07:29 AM
yeah....3.4 then..

Add your comment to this topic!