Engine surge

[whiteknuckle]

Hello everyone. I just bought my first GTP and was wondering if you gurus could help me with an engine surging problem. It started today as i was driving down the highway. I went to pass a slower car and accelerated normally. I barley got into the boost (maybe 2-3 bars) and felt the car start to surge. I noticed the boost guage was going up and down by 1 bar and the rpm was surging up and down approx. 200-300rpm at part throttle. after i noticed this i stomped it to the floor and the boost guage went full sweep but was still surging a bit (i.e. the last bar on the guage was coming on then going off with the pedal smashed to the floor). As far as i know the car is all stock except for a set of MSD wires. oh yeah, it's a 99 coupe. i have not scanned it yet but there aren't any SES lights yet. thanks in advance

EDIT: this car also has idles kinda rough. the rpms don't change (about 750) but the whole car vibrates. maybe i'm to used to my truck

[archemedes]

could need a tuneup, fuel filter, a small vacuum leak (not as likely though)

[JohnBelley]

im having a similar problem, i got a 97 grand prix se with the 3800
i asked my dad what the **** and he suggested it may have been low on automatic transmission fluid (it was about a quart low)
i topped it off and it ran fine, but about 6 months later it began to surge (the revs were climbing and falling about 200-300 diffrence) as it was running about 2300 rpm and doing about 120 km/h or about 70 miles an hour.
i took it in and got a trans service, fluid flush, new filter and pan gasket
(they have switched from dextron 3 to dextron 6 because dextron 3 breaks down under heat)

after that was finished it ran well and whatnot but not 3 weeks later the surging returned. (MOTHERF*!@ER !!!! that service cost me 250 bucks)

its still doing it and i am sorry to say that i dont know excatctly why

i assume that there is either a problem with the clutch (worn and slipping) or theres a problem getting proper hydraulic preassure (causeing failure to lock into overdrive)


i have changed the fuel filter out and it doesnt sound liek the fuel pump is the problem (i hear no grinding or anything), besides it doesnt bog or sputter or surge when im passing people, and its maintained the proper A.T.F. level.

im pretty much out of ideas.

[Sabrewings]

Find your problem on this page and it will give you info:

4T65E Transmission Info

Looks like yours is the second issue discussed.

[whiteknuckle]

yeah. it kinda sucks but you get used to it after awhile. i just learned when it starts to happen just push the gas pedal a little harder and it will quit. mines a gtp with about 140,000 mi on it so i figure the trans is due for a o-haul pretty quick and, that should take care of it.

[JohnBelley]

yeah, mines runnin about 180 thousand kms
sorry i dotn know thats it in miles

whats cool tho is the guy who owned it origanally complained about a ticking/knocking sound to the dealership so much, because of a factory defect, im not sure exactly what, but it was replaced wioth a brand new engine at abut 62 thousand kms
so it only really running about 120 thousand kms on the engine


the trans tho, is really at 180 thousand
so mines probly due for one too

[JohnBelley]

yeah, mine did leak a bit and im finding out now that it still is leaking

that may be an issue

[Smokin2000gtp]

Well if you don't feel that it's a problem with the transmission, then i would guess that you were having spark blowout. Pull the spark plugs and check the gaps on them, I'll bet they are pretty big. If this is the case just replace the plugs with new ones gapped at .055.

Oh and just to let ya know spark blowout will happen a lot more when it's raining or humid out.

[JohnBelley]

no, i know the plugs are gapped right, i put brand new platnums in when i bought it ive only put abotu 8000 klicks on since then, and they were all perfectly gapped infact, i gapped them myself

[stlmo_gtp]

When stuff like this happens i like to start with a total tune up and you may have just done your plugs but it never hurts to double check i had a similar problem and it turned out to be a vacuum leak.

[Smokin2000gtp]

Try switching to copper plugs like Autolite 104's or 605's. Plantinum plugs work great on N/A engines but don't seem to perform very well with boosted applications like ours. I'm not saying that this is the answer to your problem, but I'll guarantee it will reduce some KR if you have any.

[JohnBelley]

doublechecked plugs, had injectors serviced, checked air filter, (k&n so it was fine but i figured id check it anyway) im assuming that its a problem with a solenoid, i forget the name exactly but the dude at the dealership said it was a common problem and would be easy to fix, i just have to rip out the trand and crack it open and put a new one it, yeah, like i could do that, id **** it up im pretty sure, it could also be a bad seal i guess, he said i could be a seal is failing (i also forget what the name of it was, im not very observant, i lack listneing skills and i was hung over, gimme a break) and causing a drop in hydraulic preassure, i figure that it is the solenoid but yeah just an update.

could it be the fuel pump, im still wondering.

[JohnBelley]

mine is naturally aspirated, btw, i dont have the s/c im running cold air intake tho.

[offroadfury6]

yeah mine surges alil bit too...guessing its just a small tuneup and she'll be alrite.