Idle Issue, surge related?

Gravy · 07-20-2010

So I've run into something that a fair amount of searching doesn't yield me any answers. With the car I can start it up, drive it from here to Saint Cloud and back, and as long as I don't shut it down. It will idle, drive and behave just fine.

However, if I kill the car, shut it down or even flick the key off for one second after it gets to operating temp regardless of distance. It will want to idle at 2,500 rpms for about 30 seconds after I get off the gas, before it drops back down to around 1k. Reving up the motor, putting it in gear, nor braking will stop it. Most of the time after it starts acting up I can drive around in the country in 5th gear and never touch the gas. With the running it's self the whole way at around 2400-2500 rpm and around 55 mph. Touching the gas will initiate another 30 second delay before it wants to stop, but only if it hasn't already idled there for 30 seconds. Meaning I can feather the throttle all I want until it drops. If it is touched again, it will idle high again for 30 seconds.

I've tested the IAC and it ohm'd out correctly on all plugs. I have no issues of idle surge before it starts to act up, but when it does, the car will idle surge once or twice after coming down from the 2500 idle point.

Now I've seen idle issues like this where the idle doesn't come down, or will surge to and from the original point(2500) down to proper idle. But not heard of it holding in one higher RPM range for long.

Info on the car is as follows:
91 Dodge Stealth RT/TT(think of it as a more complicated DSM for those that don't know them)
13g turbo's
SAFC-II
550cc injectors
255 walbro
Datalogger(getting logs on the way home tonight)
GM maf translator
Dejon Maf translator pipe
FMIC

AC removed from vehicle, compressor is still in but the unit is never turned on. Problem was happening before the AC delete but was a very rare occurrence. Now it's driving me nuts, and I've run out of ideas short of buying an IAC motor even though the old one tests good.

1QUICK4 · 07-20-2010

Possible intake or vacuum leak? It's strange how it only does it after you turn it off and back on.

Could the ecu be losing drivability memory when you turn the car off?

Gravy · 07-21-2010

That was one of my thoughts. Disconnected the battery yesterday before i went down and the warm condition still occured, but not as bad. Logged a few minutes but i blew a pipe off the front turbo on the way home. So no data that will really help. Runs NA just fine with no problems.