Hello and welcome to JustAnswer!
For the idle to be that high it is very likely a vacuum leak.
Hopefully you made sure that the IAC moved freely when it was apart for cleaning. A bad IAC could cause this, but that's pretty high for the IAC to be causing it.
It could be a very high signal voltage from the throttle position sensor, but again it's pretty high for that. Unplugging the TPS would bring the idle down if it was causing it.
You don't mention how you checked for vacuum leaks but I'm assuming you at least did a visual inspection and found nothing.
What I would recommend is covering the throttle body opening with a piece of cardboard and see if the engine dies. If it stays running then it's receiving air from somewhere else between the throttle body and cylinder head, if it stays running then you know for sure there is a leak.
Obviously hoses that are off or damaged, the throttle body or intake gasket could cause this. On the bottom of the intake in front there is a plate bolted on that runs almost the span of the intake and this is sealed with a gasket. This gasket may be where your leak is and it may be something that was overlooked when checking for leaks.
I checked the IAC it wouldn't move freely at all. I managed to get the end off and begin turning it. At first it would barely move at all, after lubing and cleaning it today it started moving pretty freely. I re-installed and got a much lower idle. However it still sometimes creeps up to about 3000 RPM. Also when accelerating, the car stops accelerating at around 4500-5000 RPM like a rev limiter. Would these two issues be related?
I checked for vacuum leaks by spraying carb cleaner in the engine by over certain hoses where and where the intake is and the throttle did not return to normal so I assumed that to be my leak. Also as the car has some aftermarket mods, I took it to a tuning shop. They found a small vacuum leak and repaired it and they could not find anything else. I will check with the cardboard trick and see what happens.
Okay, I will throw the TB on tomorrow and test with cardboard to see. IF not can I replace the IAC without changing the TB or will I need a new TB?
Good news. I'll be in touch tomorrow to let you know how my TB test goes.
Just wanted to ask you also if the acceleration cut out at 4500-5000 RPM would be cause by the sensor issue or if it is unrelated?
No while idling in neutral I can rev it all the way to redline. While driving it cuts out while accelerating under load.
It has a rear O2 sensor code which I have ordered. Prior to taking the throttlebody off the first time it did not do this. After reinstalling the TB it started.
I have an O2 sensor code which and I have ordered the sensor. Prior to taking the throttle body off the first time it did not have this issue. It only started after reinstalling the throttlebody the first time.
Okay, I'll do that cardboard test today when I get the chance and see if that makes any difference and let you know. If not I'll wait until I have the new sensor installed next week and get back to you.
Alright so... I got a new throttlebody and installed it. The car wont even start now. Do you have any idea why? It came off of a wrecked RSX-S which would have had to be running as it was in an accident and was totaled. The car now just cranks but wont run. If I put the old one on with the bad sensors it runs as we discussed before but has that power cutout at 4-5 thousand RPM. I assume there's no way the throttlebody is somehow programed to the car.
Ground the black lead of your voltmeter and set the meter to the 20v DC scale.
Turn the key on.
Insert a straightened paperclip into the back side of the connector on the center wire of the TPS, push it in until it makes contact with the terminal.
Touch the red meter lead to the paperclip and read the voltage.
Let's do this for both throttle bodies, you don't have to completely install the old one, just plug it in.
You'd set the meter to 20v DC, unplug the sensor and turn the key on. Place each meter lead on one outside wire in the connector and read the voltage shown on the meter.
That's what we wanted to see.
Is the center wire shorted to ground?
Does it show resistance to ground using your voltmeter? It should show an open circuit.
It's going to have a low rev limiter in park and neutral so that's probably what you're seeing there.
We definitely have an IAC issue so it wouldn't hurt to get one coming in the mean time.
Yea I'm not sure... They just said in order to do that they would have to take the TB apart and that would cost hours in labor so they recommended exactly what we were doing.. finding one used to see. Also said I should find somebody with the same car and swap TB's to see if it runs better with a TB I know works..
I'm not sure... That may be the case. They called and it seemed they already assumed I wouldn't want anymore work done. The car is also turbo'd and they said their guess is it's something with the hondada kpro system and turbo and not TB. Even though I told them that it had no power cut out before I took the TB off for the first time and after putting it back on it had power cut out..
Yep I'm hoping. I'm order one tomorrow that will be in next week and we'll see how that goes. If it doesn't solve it then I can only assume it's a tuning issue. Although I think it should solve it seeing as it was fun until I took the TB off the first time to try and solve the idling issue.
Does it feel like it's hitting a rev limiter when this happens? It does happen while driving and not just at idle, correct?
What all modifications does the powertrain have?
Did this start right after any modification or work was done?
Throttle is opening all the way