barryweber

C-4 Corvette 1993 700 R 4 trans

I purchased this vehicle about 1 year ago with 42,000 miles and paid $5600 New paint job, interior work. I have put on about 1800 miles. Fuel injection wizards needed! Starts fine, Idles at about 1200-1400 rpm. cold, no missing. Will continue to run at fast idle no matter what one does. Fast idle 1200-1400 rpm. Half hour later still at fast idle.

When the motor gets warmed up: 180 degrees and still at fast idle 1200-1400 rpm. When I shut the car down, restart it, idles down to about 800-900 rpm, which is ok for an automatic trans car. Put it in gear rpm drops to about 700 rpm and idles ok. The fun now begins! When I move the throttle just off idle a little: surge, stumble like trailer hitching. If you drive the car, it stumbles with just a little throttle. Driving in city traffic is awful. It feels like you are pulling a trailer (Jerk, stumble, jerk jerk. Hit throttle, it revs up fine. Back off throttle to a steady speed and the stumble jerk stumble jerk.)

This is what we have done.
ECM sent to Cardone for a rebuild or whatever they do
Replaced, plug wires, plugs, map sensor, throttle position sensor, air charge sensor, engine cooling sensor, two O2 sensors, knock sensors, EGR valve, checked rocker arms. Valves seems to be ok. Compression test 180-185.

Described here is the only way we have been able to get it to run at a steady speed/rpm
Unplug the TPS, Take a different TPS plug it into the harness and leave it laying loose beside the throttle body. Seems to run at a steady speed. Throwing a TPS code hooked up this way. When TPS that is in proper place and hooked to the wire harness, there is no code, but runs like garbage stumbles and jerks.

My Mechanic is pretty sharp, but it has got him stumped. I'm 68 years old and anything with a computer should be left out of a car. My next step is to pull the motor, computer, sensors, relays and anything that is in anyway connected to a computer. Set it off in the barn and got to a speedway motor, order a 383 stroker, carburetor motor and put it in so I have something to drive.

jvp

Mod note: This was posted in the "Ask Tadge" section, and might better be served here. Bet the OP gets a quicker answer...

barryweber

I'm new to this whole forum thing so If I've put this in the wrong place I'm sorry