Hey guys, need to know what may be the problem with my LS swapped Civic. The problem is when I start my car it jumps all the way to 3 grand and goes down to 0 and keeps jumping up anywhere between 2500 and 3000 and then back to 0 and so on and so on. I have tried taking out the FITV (thanks YBlegal) and tightening the ring-cap and it was very loose but after tightening it, it made no difference. I also took off the IACV and cleaned the screen with a tiny cloth and still no difference. I am pretty sure my TPS is set correctly according to the Helms manual. Is there any other ideas? My car used to stop idling crazy after warm-up but now it is always jumping even after I get off the interstate from an hour long drive.

Also this may be unrelated but inside my car on my ex gauge cluster I am not getting a temperature reading? Could this be causing the fluctuating idle? Also wha could be the fix for this. All plugs are secure into the cluster so I am thinking it is something else.?

Any help would be greatly appreciated. Thanks in advance.

 

You need a new IACV or u have a vacuum leak. My money is that u need a new IACV.

 

When the engine is cold it means FITV when the engine is hot from runing and it bounces it means IACV. You might have a vacuum leak somewhere if it's doing it from start up all the way until you shut the car off after driving.

 

I think it may be a combination of both or just the FITV. When I took off the intake and started the car, I plugged the bottom hole in the TB (the one going to the FITV) and the rpm's dropped to 1,250 RPM area. When I held the top hole (the one going to the IACV) it dropped to 1,750 area.

 

It's a possibility. On both of my motors when the FITV plunger backed out the IACV was also all gunked up. It just happens over the years.

 

Or it could be an idle speed control valve.
took me three weeks to figure that out

 

Idle speed control valve? That one is new to me.. Are you talking about the Throttle position sensor? That only regulates how open the ECU thinks the throttle is, which would only result in high idle, not bouncing idle. Either way, my TPS is set correctly. I cleaned the IACV with throttle body cleaner yesterday, and the FITV is pushed back as far as it will go (now the little ring cap/plunger is cracked), and still it is high as ever but lower when I cover the hole.

 

ihad a bouncing idle in my last integra, i did the fitvcheck by plugging the bottom hole and it stopped bouncing. Replaced it and everything was fine.

 

The FITV might be broken and not just unthreaded.

 

Ok so heres the deal. Picked up a LS Intake Manifold off of a 2000 LS for $30 (good price) locally, and took the fitv off of it. The cap/plunger thing looked way farther in than mine would go, so I cleaned it out and put it on my car and BAM problem solved. Car starts at 1k rpm and by the time it warms up its sits around 500-600 rpm. Now when I am at red lights, I think my car is shut off its so quiet! Thanks for all the help guys.