I have a 94 Del Sol, VTEC modle, 5 spd, Intake, DC header, and MSD Blaster coil.
This has been going on for months and its driving me insane.
OK here's the story.... I start the car, everything is fine. I get in the car, drive 10 feet, put it in nuetral and it begins to surge between 800 and 1500 RPM. This used to happen only when the car was warm. Now it surges when the car is cold and warmed up. So pretty much all the time. The IAC and FITV are both new.
Now when it starts to surge i take the intake tube off and put my finger over the upper port inside the TB (there is suction on it) and the surging instantly goes away. The upper port leads to the IAC valve..... What gives?
I've back probed every sensor under the hood. All of them are getting proper voltage and the voltage drops on the ground sides are right where they should be.
For a while (just to see if it made a difference) i was driving the car with the IAC valve port completely sealed off. (Duct Tape) The car didnt surge at all....untill it reached max operating temp
Then I put a small hole in the tape, just so the car would stay running when it was really cold out. I would do some local driving and everything would be fine. It started to surge again when the car reached it's max operating temp.
The port is no longer sealed off, and it surges all the time...exept when im at a cold start up. But as soon as i drive and put it in nuetral it beginns to surge. Even when it's still cold.
Sometimes the surging will just settle itself out,
but most of the time it just keeps on surging. And then sometimes, it will be cold, and there will be no surging in nuetral, sometimes it just randomly starts to surge in nuetral, but when its warmed up it surges all the time and does not settle out.
I've done countless vacuum leak tests.... haven't found any.
Sorry for the long post, just trying to get as much information out as i can. This has been going on for months and it just sux sitting at a light and the engine just revs up and down up and down up and down.
Any ideas?