When the engine has been sat in traffic and the fan has kicked in a few times, I've noticed the throttle 'sticks' open slightly.

if I switch the engine off and let the car cool for a few minutes the problem goes away.

What could this be?

A mechanic told me to spray some brake cleaner into the throttle butterfly to clean it up. He also said if it's not the throttle iftself it could be a sensor.

 

You might also want to check the IAC valve. Refer to the service manual for the proper procedure.

 

Aftermarket throttle body?
Stock?

Try spraying the throttle body spring with white lithium grease.

 

Bone stock JDM B18C-R.

Thanks!

 

Check for build up of grime around the rim of the throttle plate and near the shaft holding the plate. Could always take the TB off clean it with some degreaser then go from there.

 

My R does the same thing only in the summer time though. I can make it go away by getting the tip of my shoe under the gas pedal, and lifting a tad bit and the idle drops right back down. I feel like its just a gummed up throttle body.

 

Thanks. Maybe your cable is a little tight? Could be my problem too.

 

No worries! If it was too tight, I think it would have the high idle all the time no matter what. My issue only happens in hot weather mostly when I'm stuck in traffic. I think the throttle plate is gummed up (and the hot weather makes it more sticky) and so that it doesn't close completely once I let off the gas pedal. But it closes to its home position once I pull up on the gas pedal.

 

I've had the same issue with my 1996 ITR. Also only happens when it's warm outside and I've been driving a while in city traffic. My throttle cable is on the looser side as well.

 

So far I've cleaned the spring and sprayed it with lithium grease, took the intake tube off and cleaned the TB and plate with some brake cleaner then a tiny amount of WD40 around the plate edges. I most likely won't know if this has worked for some time as I hardly drive the car!

For those who are having a similar problem I'd take a look at your throttle body and plate. Mine was pretty grubby in there, I suspect this was the issue.

 

I think you can use carb cleaner as well to clean the TB. Just obviously make sure the car is off when you're doing it, and that you wipe the surface dry again after it's soaked and cleaned everything up. Don't want brake/carb cleaner getting sucked through your intake.

 

I still have this issue. Anyone found a cure?

 

Even though the way my throttle body sticks differently. My car had an aftermarket throttle body. I simply changed it to an OEM one.

 

I had this issue, my tb idle screw was missing.

 

Have you checked to aee if the Throttle Position Sensor is reading correctly when the
car is completely warmed up? This could be an electrical problem as some sensor inputs can cause a "sticky" idle.

I would warm up thr car until the rad fans cycly twice, then look into your service manual for the ECM inputs from sensors such as MAP, CKP, CMP, HO2S, ECT. The manual will tell you thresholds.

If you see a few sensors that are out of range, pull the witing diagrams for said sensors and see what they have in common.

I had a car similar to this and it was high resistance on the ground wire for the ECT, TPS and FTP sensor. The car had a higher than normal idle when coming to a stop.