z28dan

My '98 Z28 seems to be stalling after wide open throttle. I get on it (to high RPM), then depress the clutch and release the accelerator to coast and slow down. The RPMs understandably drop, but drop too far and the engine stalls. I have to dump the clutch or restart the ignition to get going again. This has happened a few times.

Also, at idle, occasionally the RPMs would drop and almost stall - the interior and head lights would dim, but the engine would still run.

I did get my computer reprogrammed by ls1speed inc. I don't know exactly what they did, but I didn't really notice this issue until the reprogramming AND after the car sat unused for 3 months. Any ideas?

markp03

iTrader: (4)

I would check out the fuel pressure regulator...thats what happened with my old car took it in they pulled 1 hose off it and said yup it's the FPR they are like 80 bucks....

CATDIESEL

how many miles on the car? If high miles it could be the IAC carboned up . The IAC cant keep up with quick rpm changes or idle changes like when the AC kicks on

z28dan

It's got 56k on it, not really high miles I'd say.

Pardon my ignorance, but what's an IAC?

And where's the FPR? In the fuel pump itself? Or in the engine bay?

strokedls1

iTrader: (1)

IAC= Idle Air Control solinoid. It allows more or less air to bybass the throttle blade on the top of the tb.

The fuel pressure regulator is in the tank on the return line.

You can up the idle some and tweak with the IAC tables to smooth that out.

z28dan

Dang, so either I have to drop the gas tank to get to the fuel pressure regulator or buy LS1 edit to tweak the IAC tables. nice.

HAMRHEAD

iTrader: (8)

Don't get Edit if you get programming software. Get HP tuners. I believe this is the software speed inc uses and you can work off of their tune and just fine tune a little. I am in the same boat so I know how you feel.

1BADAIR

iTrader: (1)

My car would do that even after tuning. I had to drill the idle hole larger cause the IAC counts were too high. Your IAC may be getting slow and causing the problem

strokedls1

iTrader: (1)

Flip the idle adjustment screw into the top and increase the idle with that. You need to remove the tb to get it out of the bottom.

z28dan

hmmm this will be interesting. I'll give it a whirl this weekend. Sounds like the easiest fix is adjusting the idle. Drilling the hole will be plan B.

I also am going to check the sensor output voltages. Is there a site or list somewhere that contains nominal voltages for sensors? Such as the air temperature, IAC, etc?