Coast Surge

[architechnik]

After performing some maintenance I took my '94 GSX out for a test run. The car idles, accelerates, and handles great, but during coasting, it surges between 1.2k and 2k. The surge subsides at a complete stop and shows no sign while in gear.

Things I did that could affect this:
Fuel pump rewire w/ 20 amp fuse
Cleaned entire intake system
Removed/Cleaned throttle body
-rewired the single pin sensor? on the top of the TB, as the wire broke while trying to disconnect
-this item changed position, but I don't really know what it is or how to reset it

Is this surge from that little pin? It seems to an electronic version of the base set screw, but instead checks the position of the throttle at 0.

 

[white90gsx]

Yea I'm kind of having the same problem I just cleaned my throttle body and now when I start it the rpms stay at 4k. I think its the tps but it worked fine before I cleaned the tb.

 

[architechnik]

Ok, I seem to have fixed the problem. For future reference, or anyone who is having the same problem like White90GSX, here's what I did:

Warmed the car up again and disconnected that little position sensor (1 green wire in black shielding).
With the position sensor all the way out, I double checked the idle speed with my palm
I then slowly screwed the position sensor until it tapped the RPMs up
I backed it out slightly to make sure the idle speed was back to normal, tightened it, and reconnected the wire

I am not quite certain what that position sensor is for, but it seems to only activate when the vehicle is in motion. I could not find any difference in engine sounds or ecu/other sensor activity while idling when I disconnected it.