Ingram10

Ok, I recently bought a 98 z28 which I was told has an ls6 block with ported heads and a big cam. When I bought the car, the owner told me it needed a tune, (the car would stall out at stop lights) which I had done within a week of purchase. After having the motor tuned, the tech told me it need an IAC, which was why it was stalling out. I replaced the IAC, which stopped the stalling after the engine warms up, however, it has problems starting now, and I have to hold down the pedal to around 1500 rpm's to keep it running. After a minute or so, it will "wake up", and raise up to around 2000rpms on its own, I can let off the pedal, and it will drop down to around 1200. The other strange issue is that every so often, it will stall out when I press the gas pedal, it sounds like its missing, but then it will suddenly launch to full power. This only happens when I have first started it, whether its warm or not. The ignition coils are MSD, and look to be fairly new, so I havent given them much thought. I'm aware that this is a jumbled bunch of information, but if anyone has any ideas, they would be greatly appreciated.

conor.davis

iTrader: (20)

Just reread your post,
Who tuned it? Sounds like they might have not done the best job if its lurching and not idling properly

Ingram10

Im not trying to point fingers here, but TX Speed did the dyno tune. Could it be something as simple as spark plugs?

shaun

could need just some basic maintinence like cleaning the maf,plugs and wires,clean the tb.
also try disconnecting the battery for a hour or so and the car will have to relearn its idle when you crank it back up.
some times when you swap out sensors the car will act funny untill its reset.

Ingram10

Yea, ive already tried disconnecting the battery and letting it sit. This car also has 3:91 gears in it, and the speedometer is way off. Thats something that needs to be entered when tuning, right?

getusumws6

iTrader: (9)

I would have TSP Look at it again. They should be able to tune out the surging. What cam is in the engine? what is your normal idle rpm?

Ingram10

Yea, I think I might take it over there again. The cam numbers are 236/242 112 LSA. The car idles too high in my opinion, the tac reads around 1200 usually.