Idle issues and weird things with throttle
 

Hey guys,

I know there are a lot of posts on this topic and I've tried several things, let's say almost everything. Let me start form the beginning and tell you the story of my Civic ej9.

I bought this 2001 ej9 with 179 000 kilometers on it. The belts replaced etc. After two months the temperature started doing weird things and the thermostat was replaced. Not long after that the throttle response started to differ from when I bought the car and the car started hesitating. Engine light comes on. TPS sensor broken. I replaced it and calibrated it and I cleaned the whole throttle body while I was at it. Replaced the spark plugs too. From that moment on it was better but not for long.

When I start the car in the morning when cold it does around 2000 rpm (which is probably normal). But when it's warm it sometimes does that as wel. When I turn the car off and on again its okay, runs at 750 rpm. But that isn't the only thing that I noticed. When the car works accordingly and I am nearing a traffic light for example and I step on the clutch it does 1250 rpm until that car has come to a complete stand still. As of right now (a few weeks later) it starts getting worse again. When I do the same thing as before (the traffic light) the car runs at 1500 rpm for a short while, then it runs at 750, 1500 again and then 750. All within a matter of 2-4 seconds.

On top of that when I am driving and I hit the clutch after I let go of the throttle pedal, the rpm goes up a little before dropping.

Since I am completely at the end of my knowledge here I thougt maybe you guys wanted to help.

Re: Idle issues and weird things with throttle
 

When you cleaned the throttle body did you clean the IACV (Idle Air Control Valve) and it's gasket screen?

Re: Idle issues and weird things with throttle
 

"Good thing you ask! I did yes."

Vell (german accent), how does it idle with the IACV harness disconnected?

Re: Idle issues and weird things with throttle
 

I will try that as soon as I get home after work today.

Re: Idle issues and weird things with throttle
 

Okay, so when I disconnect the IACV it idles pretty bad. It runs at around 1500 rpm when warm and keeps jumping up and down pretty fast. Keeps jumping between 1400 and 1600 rpm pretty fast.

Re: Idle issues and weird things with throttle
 

Refer to reply #5 in this link: https://honda-tech.com/forums/honda-...c-test-764478/
Test the harness for voltage. Also remove IACV and test with 12v supply to find out if it's operating properly.
If you replace it you may want to consider pulling a used OEM from junkyard.

Re: Idle issues and weird things with throttle
 

Read it and got me thinking. When I remove the IACV it starts surging around 1400 and 1600 would it help to adjust the idle bypass screw?

Better to test IACV first.
There's a procedure in service manual to adjust the idle screw if you want to try adjusting it. My guess is the IACV isn't working properly. Any CEL's?

Re: Idle issues and weird things with throttle
 

Nope. No CELs but it seems to run better with IACV on. Without it it surges between 1400 and 1600. With it its somewhat stable except when driving.

Re: Idle issues and weird things with throttle
 

Did you remove and test IACV as shown in video?
Maybe the valve is only partially opening?

Also, throttle blade may be sticking. Try spraying WD-40 on throttle shaft spring and lightly lube the outer perimeter of throttle blade and TB bore area that surround the blade's resting position.

Re: Idle issues and weird things with throttle
 

I have a very busy workweek. I will try and do just that sunday. Thanks in advance!

Re: Idle issues and weird things with throttle
 

Oke so Ive tested the iacv and it seems to be working fine. I made two videos where you can hear the engine with and without iacv. As I said before without IACV it seems to be running pretty bad. Any ideas? Can I test for vacuum leak or something?

Re: Idle issues and weird things with throttle
 

Youtube: smoke test for vacuum leak