I bought a 1993 honda civc lx and the engine surges and i can't figure out why. It only does it when it is idling. Does anyone know what to do

 

Just a couple of things that cause surging mainly
1. Idle Air Control ( this adjust idle according to engine load)
2. Egr (could only cause a surge if it had a vaccum leak on the intake side of the valve)
3. Misfire ( if it was misfiring you should know due to lack of power but if you wanted to narrow it down unplug each plug wire while it is running and look for rpm drop if it dosent change at all that is the cly the misfire is on) little warning do not leave plug wire off for more than 5 secs without the wire grounding out it could surge and fry ecu.
4. vaccum leaks ( although you really dont see this alot on hondas it can happen and if you think that there is air leaking into the engine after the map sensor then use a can of throttle cleaner to isolate and verify leak as you spray cleaner over the leak the rpms will drop)
these are just a couple things but also the more likley ones.

 

Yea, it could also be air in the coolant system. I would try the cheapest solutions first. Try bleeding the coolant system....and like the above said.......start the engine and spray carb cleaner on vac lines one by one....if the engine sputters then you have found a vac leak. Hopefully you can fix it with one of those solutions......cheap fixes are best.

 

I'm not really familiar with import engines. Where is the idle air control located and do you have any idea where the egr valve would me located. My block is a B8 block if that helps any. When i first bought the car it would idle up and down like it's doin but once i drove it a little it would stop and now it does it all the time. I don't know if that info would help the diagnosis or not. I will try the throttle cleaner first to see if there are any leaks. THANKS all!!!!

 

a lot civics do not have any egrs, some do but most do not. if it does have on you will see a metal tube coming off of exhaust manifold up to a valve and then another tube going from that to intake manifold.

 

The exhaust manifold on my civic was replaced with a header, should the header still have the hookup for the egr?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crispyallen &raquo;</TD></TR><TR><TD CLASS="quote">The exhaust manifold on my civic was replaced with a header, should the header still have the hookup for the egr?</TD></TR></TABLE>
The egr passage is in the head, they didn't have any external pipes.

I've seen egr valves sticking open cause a low, rough idle, and stalling.

 

I bought a haynes repair manual and it said that the throttle position sensor could cause the engine to surge. i unplugged it and the engine stopped surging but it idles really high, like 4grand, and i was wondering if that could be it or not because the self diagnosis system is showing a code 17 and a code 19 which is the vehicle speed sensor and the lockup control solenoid. i'm not real sure that either one of those would cause the engine to surge would it?