I just bought a used 2004 Civic 1.7l automatic that had a front end collision which was fixed. I bought the car with 68450 miles on it and drive it home. It drove great on the test drive and for 500 or so miles after I came home. Now the other day I was driving on the interstate and at 50mph the motor started surging (gaining power, jumping speed), after driving 20 miles on the interstate, I got off my exit and the car was surging at almost any speed, but still mostly at higher speeds. Any ideas? Sort of wondering if the air conditioner has something to do with part of it, because it really bogs down when the compressor starts and stops, but not completely related. Any help would be great. Thanks for your time. Let me know if you have question.

 

My car had a similar problem and it turned out to be a loose connection on the idle air control valve. You can check by taking the factory intake off and checking near the throttle body for a loose connection. Hopefully you have the same problem and it's a simple fix!

 

My first instinct is to say the throttle cable is sticking or needs adjustment or the throttle plate (inside the throat of the throttlebody) is sticking due to carbon buildup.

Also, it may be like Pridagy says and it's a loose connection or bad sensor. Put a scanner on it. Or if you don't have access to one go down to Autozone (they will scan it for free) and post back with the exact code.

 

thanks for the advice, but I had the Idle Air Control Valve off last night and sprayed it with carb cleaner and it seems to still have the problem. Would it have a code if there is no check engine light on? Thanks again.

 

That's all fine and dandy but, did you look at the throttle cable or throttle plate? If you needed to clean the IACV then you probably need to clean the intake too.

Check for loose connections or bad wire(s).

Check for stored codes anyways. Just because the light isn't on doesn't mean it doesn't have a stored code. If you have access to a scanner with live data mode look to see if the throttle is at about 10% when at idle and about 90% at WOT (wide open throttle).

 

I doubt the A/C has anything to do with it, but you could always remove the relay for the compressor and see if that changes anything. (other than the A/C not coming on, that is)

Now, is it actually going faster when it flares, or are the RPM's just fluctuating?

Ever checked the freeze data? What's the TPS reading? (throttle position sensor)

Any stored codes of any kind? (as noted, the ECU can store codes without the MIL illuminating)



On a side note: Buy one of these http://www.helminc.com/helm/product2...C01&itemtype=N

 

took it to a parts store with a cheap reader yesterday afternoon and it said idle air control valve. they didn't have part it in stock, so I ordered online, should be in in a couple of days. Let you know what I find out then. Thanks for all the suggestions and advice.

 

^^ Ouch, that's one of the more expensive parts. Make sure to re-set the ECM/PCM and to do the idle re-learn procedure. Good luck and post back with results.

 

lazlong what are the ECM/PCM and how do you do the idle re-learn procedure?

 

ECM/PCM re-set: With the ignition OFF, pull #6 fuse in the under-hood fusebox for at least 10 seconds.

Idle re-learn: Start the engine and, with nothing on (windows, radio, lights, etc.), hold the rpms at 3,000 until it gets to operating temp. Then let it idle for 5 minutes.

* I usually do them at the same time. (pull the fuse then do the idle re-learn)