tgkaotic

Hi Guys,
I have a 93 Accord EX and I have a surging Idle problem that is driving me crazy!
It jumps between 8oo to 1500 rpm's after driving and tries to during slow driveing.
I have replaced and cleaned the old IVAC valve and tighted the FITVon the throllte body as well as cleaning the intake.
The idle still surges......
I cleaned the old IVAC and FITV and replaced then again and to no avail, still surging????
I ahve reset the ECU and Bleed the cooliant!!
Any Help please???
Thanks

apexracing

Hey bro i Have what would be the same problem on my 93 lx and am almost certain it's not my vacum system beacuse i replaced my iva, my ecu is not shooting any codes so i am wondering what it could be as i need this problem solved asap my idle jumps from normal to 3000 rpm same symptoms as tgkaotics ex. please any help would be greatly appreciated.

amckee

Any excess air that enters the motor can cause this idle surge. Vacuum leaks, IACV, FITV, EGR not seating when closed, bad PCV, throttle cable too tight, and idle screw out too far can all cause a high idle. When the idle exceeds ~1200-1400 RPM with the engine warm and the throttle plate is closed, the ECU cuts off the fuel injectors. The idle falls below the threshhold, the injectors cut back on and the whole cycle starts over again. I had a starting boost valve(accord) that was leaking through the diapham that caused mine. Something like that can only be found with a vacuum pump/guage. Anything that has a vacuum line running to it can cause this problem if it won't hold vacuum, not just the vacuum lines and gaskets. This includes EGR diaphram, Boost valve diaphram, cruise control, MAP, Intake bypass valves, Purge solinoids and others depending on model. The ECU uses this function during decelleration. The fuel injectors are cut off when you take your foot off the gas and you're coasting in gear. Some people will unplug their IACV, or TPS or some other sensor and pronounce that the problem because the surge goes away. What is happening is the ECU goes into default with the unplugged sensor and the injector cutoff function is negated. This is the same reason why the problem only occurs with the engine warm. The ECU is in default until the ECT sensor reaches temperature.

Have you set base idle? With the engine warm, unplug the IACV and set the idle to 450-500 RPM. Kill the engine, plug the IACV back in and clear the code from the ECU. If the idle is still surging, you have an air leak. Intake manifold gaskets are also the culprit many times.

tgkaotic

Wow, thanks,

I will set the idle tommorow, but my boost diapgragm has a vacuum hose that is broken at the soleniod and I can not fix it as it is under the intake manifold.
Do you see a way to fix this or just bypass the IAB compleatly?
Tommy

apexracing

Also i was wondering if the significant amount of air in my coolant even after bleeding the system could have any thing to do with the idle probelm, a friend and fellow cb7 tunner said it could be my head gasket that could be causing both the air and the idle surge wich now only occurs when the car is warm. after tightening my fitv valve body as sugested, cured it while cold but now bounces from 1000 to 1200 rpms while warm any ideas?


Modified by apexracing at 7:30 AM 8/21/2007

amckee

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by apexracing &raquo;</TD></TR><TR><TD CLASS="quote">Also i was wondering if the significant amount of air in my coolant even after bleeding the system could have any thing to do with the idle probelm, a friend and fellow cb7 tunner said it could be my head gasket that could be causing both the air and the idle surge wich now only occurs when the car is warm. after tightening my fitv valve body as sugested, cured it while cold but now bounces from 1000 to 1200 rpms while warm any ideas?</TD></TR></TABLE> Don't know if your problem is caused by the head gasket. Usually you will have water in your oil or oil in your coolant. Are you constantly adding coolant? Air in the lines will cause idle surge. The small lines running to the IACV and FITV are passive lines, meaning the coolant doesn't have to flow through them if it can find a route of less resistance. Air can cause a vapor lock in these lines that the water pump can't push through.