4doors

So I have looked over every idle post, thread, and sticky and nothing is resolving my issue.. let me begin.

I decided to paint my car. It's a 98 civic lx 5 speed. Once the paint dried I wanted to do some maintenance for it. So I changed;

-Fuel filter
-Drained radiator fluid and refilled / bleed out air
-Replaced radiator fan switch
-Replaced thermostat
-Replaced coolant temp sensor

Once all this was done I tried to start the car. It immediately shot up to 3000 RPM's and just sat there!

I checked for vacuum leaks and found a few. So i replaced the vacuum lines that went to the IAC and the lines that plugged in for the coolant.

It was still idling High but more around 2000 and then dropping to 1000 and then going on like this. So I replaced:

- IACV gasket
- IACV
- Air filter
- Air temp sensor
- Battery (just cause)
- adjusted the idle screw
- adjusted the throttle cable
- Replaced the PCV

After all this I tried to reset the ECU by:

-Unplugging battery
-Driving car until warmed up
-unplugging ECU fuse and disconnecting battery
-Letting it idle for 10 minutes with no accessories running
-Driving

NOTHING IS WORKING!!!!!!! if anyone has any suggestions other than the above please send them my way....I am completely out of ideas... on a good note though...the paint job came out awesome

4doors

one other thing...my radiator fan isnt turning on...could this be part of the problem?

KyleSJ6033

I have never had that issue.. I am an autobody technician myself but how far did you have the car apart? Im thinking a ground could cause some of these problems. If it wasnt doing this before the paintjob it is probably something stupid. Possibly the vacuum could be hooked up wrong but I doubt it. The civic is a fairly basic car and you will figure out the idle problem in time but until then it will just make you mad.

marek91

in regards to the Fan its probably at the plug for the fan switch on the thermostat housing....the wire some times brakes at the pin in the plug.....honda harnesses dont last to long...

FrankHondatech

OK first of all this seem to be related to the Air going to the engine.Too much or not enought, diagnostic are needed to know wich one is the probleme.

To reset the ECU correctly remove the fuse and wait 30 sec. No need to unplug battery.

Also on side note, Don't change random part jsut becaues you wan't too. If the Thermostats was working a honda tech would never change it. Also Stock honda with over 300,000Km sometime still have the original one working fine.
Same goes to coolant, Jobber coolant sensor are probably not following Honda original spec( Can cause idle probleme )



This -adjusted the throttle cable Should never be adjusted NEVER!!!. The only time you adjust it its when you replace the cable.


And the idle screw is not here for adjustement at all. Its there because honde used it when they installe the throttle body for the 1st time. Never a honda tech will touch this.

The idle has to be ajusted with the Honda Scan or any professionnal grade scan that can perform an Idle Relearn. All the stuff you changed is not related to ur Hunting issue.

FrankHondatech

The fan only start when your engine coolant hit 105C

To test if you coolant is correctly filled and bleeded.

2000 RPM for 2mins. If the fan don't start you have a probleme with the coolant. Or the new coolant sensor doesn't fit the honda specs