so im still hunting for the problem that is causing my surging idle. The car surges when its in park put not in drive. but when i disconnect the tps sensor on the back of the trottle body. The car idles fine. Just a bit high. I also tested my iacv and it clicks. What could be the problem? thanks

 

check the fast idle valve.

 

I already checked and cleaned the fast idle valve but it didnt do anything

 

What year is this?

The 4th gens had a valve (can't remember the name-air boost?) on the other end-left/drivers- of the tb that can clog up causing this issue as well.

 

The year and model info would be helpful. Is the throttle cable too tight? Is the idle air mix screw properly set? Are you low in coolant/ air bubble? Do you have any vaccuum leaks? Are the vaccuum lines to the manifold/ throttle body properly routed? What is the cars idle while in gear? Does it also surge when you are in Neutral? If all these preliminary checks are ok then I would look at hard parts. First the FITV. THen the EACV(IAC) in that order.

 

It is a 1991 honda accord ex. Throttle cable is not tight. coolant is good, although the radiator leaks. im thinking there are vacuum leaks. When i put my hand over the throttle body the car idles low like its about to die, but doesnt die so im assuming it getting air from somewhere else. it does surge in neutral. car idles at about 1200 rpms in gear

 

If the IAC and FITV check out be shure to check the air boost at the other end of the TB

 

I just fixed the same issue on my 92 after months!!!
After replacing ALL gaskets...I finally ended up blocking off all of the possible leak locations to the manifold: boost valve, cruise control, mount solenoid control valve...which didn't help. In the end, my problem was a bad EACV (iacv) and worn FITV gaskets. I had to block off both IACV and FITV along with everything else to get my idle down to a safe level while diagnosing and driving...letting only sufficient idle air in through the idle screw, making for rough, erratic idle...but ya gotta do what u gotta do, right?

The surging idle occurs at anything over 1500rpms and a closed throttle. Bringing it under 1500rpms in any way will stop the surge. How did you check your IACV??? I would look there first, they go bad often. I went through 2 used ones in 6 months. If your rpm's drop alot when using the rear defogger in gear, that's a dead give-away for a bad IACV. You can also do a voltage test on the TPS with a multimeter. Also, like Kwayracing said...make sure your idle screw on your throttle body isn't backed out too much.

 

well i sent 9 volts to the iacv and i could here the solenoid clicking so im guessing that it works.

 

Wasn't the iacv on these a rotary valve controlled by magnetic opposition with a duty cycle?

 

It's a pintle valve controlled by voltage pulses (counts) from the ECM...

If you remove the EACV or FITV...you should put new gaskets on them...they're cheap and not doing so could easily create a vacuum leak

 

I vote vac leak. A few friends had surges from leaks and my 95 Prelude H22 had a loose intake manifold causing the same.

 

well i sprayed carb cleaner by the iacv and fitv and the idle did not spike at all so i dont think that the gasket is bad?

 

Just because it clicks doesn't mean it's working correctly. The seals inside can go bad leaving a gaping hole. People pull the iacv's from most cars in the junk yard all the time so your best bet would be get one off ebay from a reputable seller for like 40 or 50 bucks. I went this route myself a while back. This assumes you're sure it's not a vacuum leak.

 

well all i did was remove the head, so i didnt really touch any vacuum lines. When i put my hand over the throttle body opening the car idles lower but does not die. Is that a sign of a vacuum leak

 

Have you looked for this fix on cb7tuner.com? There are a number of threads on fixing this very issue.

 

Vacuum leak simply means it's leaking vacuum, it doesn't mean simply from a vacuum line. It could be by the injectors, which I found to have occurred the last time I took off my intake manifold. It could be anywhere on the intake side. You can put some water inside a spray bottle and spray a fine mist around the intake side and see if the idle changes to find the vacuum leak. If you don't find one after extensively checking I'd get a used iacv.

 

Does the surging idle go away after it wams up?