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Engine Surging on 08 Grand Prix 3800

R

Redthe08GP

New member
Hey everyone,

I've been having an issue for the past month or so where my engine will surge from about 1500 to 2000 rpm back and forth under gentle acceleration or going up hills. It goes away when I apply more or less pressure to the throttle. It does not surge at idle when the ac is off. I don't believe it is related to the ac because it does it when it is on or off. I installed new spark plugs/wires and replaced the trans fluid 10k miles ago. 210,000 miles, original engine, transmission was replaced with a low miles one from the scrapyard at 170ish when I bought the car.

Thanks,
Christian
 


Have you removed the TB and cleaned it? If not, give it a try. Bet the backside of the butterfly is all carboned up. Gotta love DBW. Might also try cleaning the MAF sensor with the MAF approved spray. Don't touch the wires to clean it, just spray it clean and let it air dry.
 
When the surging starts, keep steady on the throttle and with your left foot tap the brake pedal and see if it stops.
 
Both of my cars have had a similar issue before. My '04 Comp G did that after I accidentally broke a tiny vacuum line coming off the LIM. Went away when I replaced the line. My N/A '05 Impala did it for quite a while too, and quit after I replaced the transmission. I think it was the torque converter clutch engaging and disengaging because my tranny was toast and all the solenoids were coated with clutch material. Triple Edge Performance has a brief article about that particular problem: TCC rpm oscillation
 


I'll have some diagnostics done when I return to Bloomington in August. I was just hoping there might have been a common fix for it that I could just throw in without having to deal with that whole process
 
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