Prypiat

I have read for hours regarding this issue and tinkered with the car for hours trying to remedy this to no avail.

The car idled fine until I pulled the IACV off and cleaned the throttle body. The idle surges while the engine is warm as well as a cold start. I replaced the TB gasket as well as the IACV gasket. Plugging the IACV port with my finger causes the idle to steady out.

But, I pulled the IACV and it ohmed out fine. I also put 12v directly to the coil as a test and took video of the valve opening and closing. It only opened a couple mm but it clearly opened to allow air passage.

I checked the signal wire for the TPS sensor and it is performing perfectly: .5 - 4.5V.

Out of curiosity I ohmed out the IAT sensor and either I can't get my probes on it correctly or it is reading a ridiculous number (like 10ohms) instead of 1-4K. I may pull it off today and investigate unless you guys can point me in another direction? I have reset the ECU by disconnecting the battery at least 10 times but it immediately starts idle hunting after firing up.

grumblemarc

iTrader: (4)

Air in system? I don't see where you bled the coolant.

Prypiat

I bled the coolant at least twice. I followed youtube videos. Started car, allowed the engine to warm up, kept adding coolant to radiator, and used the air bubble bleed valve.

I just went out and did some more troubleshooting - when the engine is warm, the FITV valve port being plugged by my finger effectively does nothing. When the IACV valve port is plugged, the idle goes from high and wandering to almost stopping the engine. I can keep the IACV valve plugged and the car idles but at a low (probably the correct) RPM. I ordered a tachometer that will be here next week so I should be able to confirm RPMs soon.

grumblemarc

iTrader: (4)

Clean the FITV while you're waiting.

Prypiat

I pulled the FITV although I didn't fully disassemble. The car came from up North so nearly everything is salt corroded and hard as mess to disassemble. I'm having to use an impact screwdriver on nearly every screw. When I realized I was going to have to vise the FITV to get the screws out the ends I just said screw it and sprayed it out with cleaner. Is it worth pulling off again? It looked really clean and the cleaner that ran out wasn't anything like dirtiness that came out the IACV valve.

Prypiat

All right - So I put a new timing belt on the car and adjusted the valve clearances. I bought a laser tach and found that my idle was WAY too high. Like on the order of 1500 rpm.

I had to run my idle screw all the way in just to attain an idle in the range of 700 but it wound up being 1050 - 1200 between the idle fluctuations once the IACV was plugged back in. What does it mean when you have the idle adjust screw all the way in just to attain regular idle speed? Other than the slight fluctuation the car runs great. BTW, I am taking tach readings off the flywheel. This may be incorrect but makes sense to me.



[edit] This tachometer has great reviews on Amazon but clearly lacks in the QC department. Apparently someone ran out of faceplates for tachometers or either some chinese guy didn't know any better.

Fliptard

I'm curious as well. My GSR in my 97 has the same issue. No matter what I did it always surges. So i took a piece of 22 gauge steel and made a block off between the IACV and intake so no air passes through, Cut my idle down to perfect, except now that its freezing, It doesn't like to stay running unless it's warm. And my idle screw is ALL the way in as well.

Prypiat

Finally got some miles on the car - Drove it 50 miles this morning without issue post the water pump, timing belt, valve adjustments, CV joints, rotors, pads, steering rack, inner and outer tie rod ends, coolant flush, idle adjustment, IACV, FITV and TB cleaning.

There is still something clanking when I hit something abrupt in the front end but I will take care of that at a later date. Unless my tires start wearing oddly..

Prypiat

My question still stands: Having to run the idle screw all the way in to get the recommended idle indicate that there is a problem such as a vacuum leak?

Former User

Have you tested the ECT sensor?

MT916

I had the same issuse adjusted the i belive is called fast idle air control valve turned it all the way in and runs fine now...


Posted from Honda-tech.com App for Android

Prypiat

OK, so I narrowed it down to the IACV. If anyone has a detailed breakdown of the IACV I would love to see it. I have looked online and didn't see anything.

Meanwhile, my car never indicates a higher temperature than this:



Is this normal?

Former User

What did you find that narrowed the problem to the IACV?

Detailed breakdown?

Your temp gauge shows normal operating temp for a Civic engine.

Prypiat

Detailed breakdown as in a parts schematic. I can't find anything that shows the internals.

I narrowed it down to the IACV by bringing the car up to operating temp and, with the idle screw all the way in, and with the IACV unplugged, the idle was over 800rpm. I plugged the FITV port and nothing happened. I plugged the IACV port and the engine RPMs dropped to stalling. So even with the IACV valve not plugged into the vehicle it is allowing air to pass.

Former User

Post a picture. Have you tried taking it apart? The IACVs on my 96-00 Civics can be partially disassembled.

You might also want to scout for a replacement at junk yards.

Prypiat

I completely disassembled mine... I'll pull it off the car again in the near future..

Prypiat

How exactly does the IACV work? If I pull the IACV valve and blow into the inlet, should air be allowed to pass through if I blow hard enough?

Is the output of the ECU digital (12V or 0V) or does it have some sort of analog output? (pretty dumb question)

If 12V is put onto the IACV all the time, would air be allowed to pass through or not pass through?