My FD Idle fluctuates between 1100-1500rpms, fairly quickly. With the ac, headlights, heater, rear window defroster or anything that puts a load on the electical system the car idles at 1,500 with no hunting. Kinda funny.

I've allready removed the upper intake, removed the double throttle, and coolant flow to the TB, hoping that was the problem. But it did'nt change a thing.

Could it be a ecu problem, intake leak, or the tps out of adjustment? Anyone want to shoot me in a general direction?

Thanks, CJ

 

I dunno, but if you find out. Let me know, because I have the same problem. I've just been living with it.

My idle will get stuck at around 2050 rpm when coasting, then when at a complete stop, it will go back down to the 1.1-1.5k thing.. Or if I blip the throttle while coasting, it will drop back down also.

It started after I remove my entire UIM/TB/Intake elbow (and all the vacuum hoses attached). And replaced my spark plug and wires.

 

Mine started after i installed the M2 intake, profec b, and efini y pipe. CJ

 

I'm gonna go with vacuum leak on this one. Did you replace all of the gaskets when doing the Efini Y-Pipe? Easiest way to check for it would be to take some Carb Cleaner and spray around all the mating surfaces (Elbow, TB, UIM, etc), if you hear the idle flucuate when spraying it then you've found your leak. As for the increase in idle when turning on accessories, I believe that is a normal function that's just being exagerated by your other problem.

 

Check your TPS (Throttle Position Sensor). If the resistance is jumpy or bad, it will cause the symptoms. I had two GSL-SE's that did the same thing and they were NOT the TPS though. I never did find out, but read a post about a year after selling that said the Throttle Body was dirty and gummy. After cleaning up, the problem disappeared for the guy.

Tim

PS, I noticed the idle hanging high when I put the car in neutral, but when I pressed the clutch in, the idle would start hunting quickly again(Idle to about 1500rpm and back). Let the clutch out in neutral again, and it would High Idle again (2500rpm)

Also make sure your engine is well grounded.

Check for vacuum leaks using a propane torch. Remove the end of the nozzle and attach a rubber hose. Turn it on and off quickly at the suspected area and if the RPM's change, you probably have a vacuum leak.

 

There is a idle control valve that adjusts
the idle to what the ECU tells it.The TPS
can get a bad spot on it where the linkage
is set at closed position and cause the idle
to stay up.Try closing the air bleed screw
fully, back it out one whole turn, then reset the idle with the idle set screw.
Cameron at Pettit Racing told me about this
fix as I had the same problem after I re-
built my engine.My three thousand hesitation
at change-over also got noticeable better
after this simple adjustment.Good Luck

 

Mine did that.. But i removed the coolant line from the TB and did not wire that door open enough! Id check that!

 

What i did on the TB mod was just remove the spring, and tighten the screw all the way down like it says on the Robinette page.

Thanks everyone for your help. If anyone else has any ideas let us know. CJ

 

try wiring it open! I am pretty sure thats yoru problem!

 

Ok....its kinda fixed...but not realy.

Here's what i did today. First of all, i pulled out the pettit ecu, and replaced it with my stock ecu. I did not drive it, because as everyone knows that with all the mods i've done to my car, a high idle would be last thing i would need to fix. All i did was let the car warm up. Let me tell you, it was still running lean. Lean enough to make the down pipe glow after 10mins of idling! With the stock ecu in the car, the cars hunting completely vanished, however it was replaced by a 1400-1500 rpm idle. I figured maybe the ecu was taking a crap on me. But for realy no reason at all, i decided to put the pettit back in. Once back in, it just had a 1400-1500 rpm idle, but with no glowing down pipe So i took it for a quick spin...still no hunting, just a high idle. So taking want2race idea, i started looking at the sensor on the side of the TB. It did'nt realy interfear with anything, but it i'm not saying its not still part of the remaining problem. But thank you Want2race. Anyways, next i attached a jumper wire (ten to grnd) to try adjusting the idle down. What i found was the screw was allready all the way in on the air bleed screw...so i backed off the little screw on the side of the TB, and voila! Idle is now down to 850rpms, smooth and steady.

The bad news, the idle bleed screw is in all the way, and the adjustment screw on the side of the TB is only touching by about 2 full turns. So what i'm thinking is there is a vaccum manifold vaccum leak somewhere. With my luck, its going to be the lower intake manifold leak But i realy appreciate everyones help.

By the way jr, my dad and i sprayed the crap out of the car, with no luck..so thats why i'm thinkin that it's the lower manifold.

Thanks again, CJ

 

Ugh... sorry to hear that, it's a bitch of a job. Eliminate all other possibilities first. Good luck.

 

I've seen it happen with a clogged cat, sounds goofy but if you can't seem to find it look there.

 

martini that was exactly what my car did. It only did it when the air was off. I didnt have mine charged. It was weird. Someone told me it was the Idle air control on the back of the throttle body there is a pin and if it backs itself out it does that. Never got a chance to fix mine.

 

Thanks for bringing this back from the dead.

What it ended up being was the lack of a gasket on a blockoff plate for the double throttle. I bought the UIM from a friend, who had recently bought the engine from anouther local guy. I just figured it would have a gasket behind the block off plate....but I was wrong. Anyways, lets let this thread die. CJ