Today I picked up a 1997 Integra. When I was looking to buy it I figured the idle was rough because the car was cold/hadn't been driven much, but upon driving it 40 minutes back to my house the same problem was occuring. Currently it has an intake, headers with no cat straight to some generic "performance" exhaust. The check engine light is on but I believe it to be from the lack of a cat. I need some ideas as to why it's running like this and where I should begin to attack the problem. Thanks.

Here is a video of it. The reving is NOT from me, it is doing it on its own.

http://www.youtube.com/watch?v=xNzNCw25kfc

 

Check spark plugs, wires, and cap/rotor. Usually idle and misfire problems seem to trace back to timing, spark or fuel.

 

Thanks man, anyone else have any ideas?

 

check the codes first. ALWAYS check the codes first
then report back

 

Anyone think it could be the Idle Air Control Valve?

 

Bump

 

Sometimes there may be no codes for the problem. When my distributor took a crap on me on my last car, there were no codes. I found out by swapping the distributor out and putting in a spare to see if it still happened. It did, so I knew it was a bad distributor.

Spark plugs wont throw a code, he has to physically take them out and inspect them along with other factors that could be contributing to the problem.

Remove the IACV and clean it. That could also be the cause of the rough idle, and is a fairly easy process to do.

 

they'll set a misfire code. but the problem needs to persist at least 3 times, i believe, in order to set a code
and yea, you won't get a code if the problem is completely mechanical and doesn't interfere with anything electrical that is monitored by the pcm, but it's always better to check first rather than going on a wild goose chase, firing parts at a problem...like many seem to like doing for some reason

 

Check the plugs for MAP and TPS. People mix them up all the time. And check voltage on that TPS. You definitely have an air related problem there, but your rough idle might also be from worn plugs or other things at the same time.

 

check for a disconnected vacuum line.

 

I had the same problem once on my 88 Integra - after my car reaches operating temp and at a stop, the engine would idle high to about 1700 RPM then rev back down 750. When air comes into the throttle valve the pcm adjust (adds more) fuel. But since it's at idle, the throttle plate is closed, the pcm thinks the car is decelerating so it cuts off fuel until low idle. Because of the extra air the engine is sucking in this starts the cycle again. Most likely there's a vacuum leak in the IACV. This is expensive about $175 (RockAuto). So, you may want to eliminate other possible causes first by checking vacuum leaks at other locations. Start by disconnecting 1 vacuum hose one at a time from the throttle body and then plug throttle side with a rubber plug or use your finger - if the idle stabilizes then there's the leak. Otherwise connect the hose back and work on the next vacuum hose. If all vacuum hoses cks out Ok. Then try cleaning or replacing IACV. JYs (junk yards) will charge a fraction of a brand new unit. Good luck.

 

Thanks GeekNow, nice first post.