I have a 86 GXL.
Cone filter.. High Flow cat, and custom catback.. Apexi SAFC (not tuned)...

I have these items install and my idle surges from 1300 - 1600 constantly... When you start the car cold, it will not do the quick warmup that it did before. (Where it goes up to 3000k and slowly comes down.) Also, I checked tps, and everything I could possible find on the forums and throughout google. I was wonder could the airpump be causing this issue? If i hold the throttle steadily anywhere between idle and 3500k it surges. I still have the airpump connected, with the belt on. Also I just a filter on the end that connected to the airbox and on the end that connected to the split air pipe. Please let me know if anyone has any ideas on this issue. This weekend I plan to get new plugs wires and fuel filter, and that this fixes the issue, but I really think it maybe the airpump still being connected. Also on my narrowband o2 sensor anything under 3500k reads extremely lean. Once it goes over 3500k its over on the rich side.

 

Do you have emissions removed?

 

I had a similar issue and it ended up being a bad mass air, sometimes the trap door does not close completly and causes a vacuum leak. It will cause the ECU to go nuts trying to smooth out the idle, mine would just keep bouncing up and down, it was so annoying. Even if you would hold the gas slightly the idle would still dip down and up

 

emissions are not removed. only the cat is gone. Last night I swapped out mafs so I know that isnt the problem.

 

new plugs in. Same issue. Hooked up the cat again and air pump. Same issue. I have been trying to adjust the tps without jumping the initial set coupler. So that might be my problem. So Here goes.

 

issue fixed... was a coolant line going from the thermostat housing to the intake manifold.

 

Can you explain? Does anyone else have any idea what he means? How can a coolant line fix his problem?

 

The coolant line in question was attached to the BACV, an emissions related item that adjusts idle rpm when accessories are in use (mostly the AC), another related item would be the bypass air solenoid valve that is usually located just next to or beneath the BACV, it too helps control idle, and when its acting stupid it can cause a high bouncing idle. Neither of these valves are 'needed' if they fail, just block off the area's they have air/coolant running to and be done with them.