Rep Power: 0

I have a 2001 Civic LX MTX with 205,000 miles (no modifications other than a Typhoon CAI). Just recently I have been having severe problems with my engine's idle. At a stop the engine RPM will drop to about 300 RPM and then go back up to 800 RPM and then back down again. The check engine light comes on and goes off about 3x in a day. I was for sure it was the O2 sensors, so I replaced both of them. I also reset the ECU. I thought everything was fine, but sho nuff, 2 hours after replacing the O2 sensors it started acting up again. I checked most of the hoses and can't seem to find a vaccum leak.. I also raised the idle signifcantly, but it did no good so I put it back to around the stock setting. Anyone know what might be causing this? Is there a way I can manually check for codes? And lastely do those diagnostic things at atuomotive stores really work? Thanks for any help!

Electroscantch

 
Rep Power: 0

yes, those diagnostic things really do work, when u do have the CEL on, go to an auto parts store, and have em diag it for u, honeslty, it sounds like a misfire, check your sparkplugs for proper gap, and check your coil packs for holes where the spark could travel through to the head...

 
Rep Power: 812

i think you just need to pull the throttle body and give it a good cleaning. and the IAC valve which is bolted to the throttle body where the coolant hoses go into. here. make it look like this lol. get new gasket for the IAC valve and also the TB to intake mani. then when its all put back, do the ecu reset and idle learn procedure. i had idle problems at 30k miles and cleaning everything out (which had severe carbon buildup all over) fixed everything.

 
Rep Power: 0

thanks for all the help guys.. I went out and bought one of those code readers, and sho nuff, it says Throttle/pedal Position sensor A circuit low Imput, so I think you are right on gearbox. Does this mean the TP sensor is bad or will giving the TB a good cleaning still work? Thanks! Form what I read the TP sensor can't be chaged, so I'm hoping that I can just clean the TB .

 
Rep Power: 812

i would try the cleaning first, if that does not work, a whole new throttle body is needed, since the tps sensor is not replaceable (well it is, and i can send you a free spare i have, but it needs to be adjusted properly). but used TB on ebay is only $50 so thats your best option if cleaning doesnt work

 
Rep Power: 0

Is there a difference from the AT throttle body's and the MTX throttle body? The ones on ebay seem to all say AT/ Also, how hard is it to adjust the TPS sensor? Thanks so much for all of your help.

 
Rep Power: 812

yeah there is a big difference. a manual TB on an auto car will run like crap. not sure what it does switched around but something is different. make sure you get the right one. the tps needs to be mounted somehow, you need to tap screws and attach it first, then move it around with the car running and a multimeter until you get the proper idle voltage. as you know, the stock tps is held on with rivets that you must cut off to remove it. and you need a gasket which im not sure where to get. i think its alot easier to just get one from ebay and swap the whole thing.

 
Rep Power: 318

Gearbox, where do the Ritz crackers go?

 
Rep Power: 0

Thanks.. I cleaned the TB and it runs sooo much better now, but the check engine light came back on. Odd, because I am now getting a different code, stateing that my o2 sensor's heater thingamabob is bad. I just replaced both of the O2s with new ones, so I'm mystified.. I will probably just drive it with the check engine light on so long as it keeps driving fine. thanks again for all your help.