Justin11141

I have a 97 camaro z28 lt1 with 110k miles. It cranks hard when starting like 1-3 seconds on a cold start and today when I started it the rpms dropped to like 450-550 and there was huge vibration. Usually rpms at about 700 idle. I've also noticed there is sometimes a delay in acceleration I think. any ideas on the problem?

Injuneer

Manual or auto trans (different programmed idle speeds M6=800; A4=550 in gear)?

What do you mean by "cranks hard"? .....starter cranks the engine, but sounds very "labored" (slow, struggling)? Or, on extended starting period..... multiple normal speed cranks instead of just a quick start on turn of the key?

Any significant engine mods? Reprogrammed or stock tune?

Justin11141

Its a manual trans. It sounds labored and it takes an extended period of time to turn over. I bought the car off craigslist and Im not sure it has the stock tune. It has headers an exhaust an upgraded suspension and a could air intake. Also when I get into first gear to move it feels slow and labored for a little bit until like 2-3k rpms then second gear seems fine.

Injuneer

Check the battery, check the battery terminals for corrosion, check the main wires to the starter for corrosion and damaged strands in the wire, check for a poor contact at the 12V wire to the starter.

After the build, my stroker was cranking slower than normal, and taking a few extra seconds to start. I thought it was just the rebuild, straining the starter. Eventually I changed the starter, and it was like a whole different engine - started on the first twist of the key, just like it did when I bought it new on 1994. Aging starter, toasted by high header heat was drawing too many amps, and dropping the system voltage to the point where it affected the injectors.