I just put a new engine in my 87 iroc-z last week and i can get it started but it barely idles and sometimes stalls. In park it idles around 500-750 and in drive it is usually below 500 if it even stays running at all. I had to advance the timing to even keep it running, and seems to run fine when i give it gas. Something else weird it does is when in drive the car shakes at around 1500-1700 rpm, after that its smooth. I did put an upgraded cam in the engine during the swap, does this sound like a vacuum leak somewhere? If anyone has any ideas please help!!! Thanks

 

need a little more info on your car is it carburated or injected???? on the vibration issue how old are your tires ?? it could be a number of things really from a warped rotor bent rim or even as goofy as a driveshaft out of balance.......

 

Just finishing the swap? How did you install the cam? (advanced, straight up, same as the one you pulled out..?) Sounds like you just need to find the right timing, get a light hooked up so you know what you're dealing with. Vacuum leaks will definitely complicate things, so checking over your work with vacuum lines and bolts around intake gaskets would be a good idea.

PS. Post your cam specs.

 

ok today i replaced the maf and it doesnt really stall anymore but something is still definitely off. I know its not the tires cause it shakes at the same rpm in every gear. At idle it shakes and around 1500-1700 rpm. My cam specs r 207/212 intake/exhaust, and the lift is .420/.435, oh and it is tpi. I bought a vacuum gauge, and im gonna check that tomorrow. Also i'm getting real bad gas mileage. Do you guys think maybe one or some of the spark plugs arent firing? or anything with the harmonic balancer?