Rough idle on cold starts

[seanpatrick]

Sup fellas,

I've got a 98 Civic LX that has been having an issue for some time now but haven't been able to fix. I do routine maintenance and have a relationship with the local repair shop. Plugs, wires, conventional oil changes all done on the regular. I clean the battery terminals, have replaced the distributor cap/rotor and also the fuel filter, but the problem still exists, regardless of temperature.

When I start the car it turns on no problems, but then drops RPMs like its choking. It lasts for 5 to 10 seconds and it goes away when the car is put in drive or reverse, or if slight throttle is applied. It does not happen if the car has been driven, turned off for a bit, and then turned back on.

Any ideas on what I can check?

Thanks for reading!
Sean

 

[RonJ]

Are you working with a mechanic or do you plan to fix the problem?

Stock 98 Civic?

CEL codes?

 

[seanpatrick]

Myself.

Stock.

Yes - 1 continual code - p0420 for cat converter
Always have to use the crc gauranteed to pass with a code reset using my ultragauge before it will pass inspection.

 

[RonJ]

Myself.

Stock.

Yes - 1 continual code - p0420 for cat converter
Always have to use the crc gauranteed to pass with a code reset using my ultragauge before it will pass inspection.

Assuming you haven't recently reset the ECU, if you check for CEL codes right now, are any new ones thrown?

 

[seanpatrick]

Ecu hasn't been reset in a few months, only throws that code with no pending codes.

 

[RonJ]

only throws that code

Now or months ago?

 

[seanpatrick]

now .. the code has been thrown for a few years now. I only reset for inspection otherwise I leave the cel on.

 

[RonJ]

Clean the IACV. If the problem persists, adjust the idle speed as instructed in the service manual.

 

[seanpatrick]

Ok will post results on Sunday. Going to follow diy in your sig.

Thanks for suggestion.

 

[seanpatrick]

Well I'm embarrassed to say I can't find the IACV. I watched a few youtube videos but where it was for them it is not there for me.

Can you point me to a guide that shows me where it is under the hood? Do I have to remove something before I'll see it?

 

[RonJ]

It has two coolant hoses attached to it: