• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

2004 Grand Prix GT2 lurching/surging when applying throttle

gunbunny

gunbunny

New member
Yesterday morning, went out with the family to head out shopping. Air temp about 50 degrees. Started up the GP, drove 2 blocks and stopped at a store for a few minutes to pick something up before we headed to our final destination. Got back in the car, started it, and it nearly stalled. Gave it a little gas (TB needs cleaned, so this is normal), put it in reverse and gave it a little gas. The car started bucking and lurching as it went back. Tach kept bouncing up to 3-4000, but the motor noise sounded more like half that. Put the car in drive, gave it gas, same deal. With each push of the accelerator, no matter how hard, the motor would lurch and surge 4-5 times before returning to normal idle. I limped back home, we transferred to my wife's car, and went on our way.

Got home about 2 hours later. Plugged in my code scanner... nothing. Started the car, nothing. Ran fine. Let it run a bit till the temp came off the peg, still ran fine. Exhaust smelled rich, and it's been getting crappy mileage the last couple tanks. I just chalked it up to my driving. (I do like jackrabbit starts.)

My gut is telling me it's a bad sensor... ECT (engine coolant temp), IAT (intake air temp), MAP, or MAF. Had something similar happen to my last car, but can't remember which it was. Without it throwing codes, how can I diagnose this?
 


Start off by cleaning the throttle body. Could be as easy as a sticking throttle plate.

When sensors go bad, typically the pcm will see it and toss a code.
 
my icm started to act up, i could feel a small misfire and then it would stall. it only stored a pending code till it stalled out the 3 rd time, then it set the cel light.

oddly enough i cleared the code and it never acted up after the last time. that being said, clean your TB then keep your scanner in the car, drive it till it acts up again and scan it asap should it act up again.
 
Took it out this morning, seemed to run fine. Weird. Though now that I think about it, it was more of a chugging. RPMs would cycle up and down between 4000 and 1000... whum-whum-whum-whum as long as I was applying throttle. Couldn't get it over 5mph.

Maybe the fuel filter? It's been... A long time... Since I had it changed. 140k on the odo now, was still well below 100k last time I had it changed.

I'll take it out again this afternoon see if I can replicate it.


Sent from my iPhone using Tapatalk
 
Couldn't replicate it. Had it out a while, did jackrabbit starts, multiple off-and-ons, coasting, highway, stop-and-go traffic... Nothing. So I put a new fuel filter in anyway, Lord knows it needed it. If it happens again I'll report back.


Sent from my iPhone using Tapatalk
 


You must log in or register to reply here.
Back
Top