Thread: 2008 Grand Prix rough start

Hi there, so I recently bought a 2008 GP and it has been periodically starting pretty rough and some of the time it will die. After it dies it starts very rough. I'm not real sure where to start, MAF? There is no CEL. Car has 140k miles on it

Sounds like it might be the CPS or crankshaft position sensor. Just by your description, it would fit the problem, however, obviously it's not a certainty that's what the problem is. But if I were you and had just bought a used GP without records I'd replace it anyway. One of those simple sensors that can strand you on the highway when it goes bad. BUT, if you do buy one, get an ACDelco and not some Ebay knock off, I got burned on buying off brand sensors, never again. If you're comfortable wrenching, its not hard to do. Shouldn't take you more than an hour if its your first time doing this repair.

Pull the throttle body and clean it inside and out, likely covered in carbon. Clean the MAF with the correct MAF cleaner (not brake cleaner). New plugs and wires if unknown when (if) they were ever changed. Stock plugs go for 100K miles then change out.