ICV Questions

[Lucas.B]

Hey guys,

I'm still having the same cold idle problems - sluggish throttle response and the rpm's dip really low upon letting off the throttle. I've replaced many sensors, but today I spent some time on the ICV:

Resistance is about 38 on the outer two prongs, about 18 - 20 for the centre and either end - the haynes calls for 40 and 20, so thats good.

Voltage on the leads; the haynes calls for about 10 on the centre prong, mine shows 4.xx and 6.xx, is that way too low?

Now here's the thing, I became so convinced it's the ICV because I started the car (problem was there) and then unplugged the harness to the valve and practically nothing, if anything at all changed, and the manual says it's supposed to rev up to about 2000 rpm when you unplug it, which makes sense since the valve will just stay open.

Now with that in mind, but with my voltage and resistance readings, what do you guys figure? Can the valve be faulty but still show proper resistance readings?

Thanks so much, any input is really helpful

Lucas

[ethree]

Is it clean on the inside? Perhaps if it was gummed up the resitance would be correct but not allow the valve to open and close properly?

[nickpdx]

If you haven't tried cleaning it, try doing so. I was having the same idle issues when the weather was cold. I ran some carb cleaner through the ICV and Seafoamed my engine and all problems were resolved.

http://www.r3vlimited.com/board/showthread.php?t=111370

[Lucas.B]

Yeah, I've cleaned it several times.

By the way, my idle problem is very odd. At operating temperature the car runs perfect, idle and all, also, if I've reset the ECU (disconnecting the battery for a bit) The car runs perfect, even when cold. But it quickly (within two to four trips) goes away and the symptoms return.

[ethree]

Tried swapping in a known good dme/ecu?

[blazing]

Now here's the thing, I became so convinced it's the ICV because I started the car (problem was there) and then unplugged the harness to the valve and practically nothing, if anything at all changed, and the manual says it's supposed to rev up to about 2000 rpm when you unplug it, which makes sense since the valve will just stay open.
Lucas

I have also tried this and had the same results,same symptoms as your car to boot.
With the ignition on and looking into the valve does it mostly close and chatter?

[Lucas.B]

Hey thanks guys for all the input

To the above poster, the valve just buzzes (like it's supposed to i think) when the accessories are on. How do you mean looking into it, take the hose off?

[mikeedler]

check your ecu temp sensor.

[Lucas.B]

check your ecu temp sensor.

That was actually the first thing I changed, put a brand new one in. All the symptoms pointed to it, but it didn't change anything

[blazing]

Yeah with the hose off.
I still have no clue if mine works right or not but if this thread leads to a resolution it would be awesome.

[Lucas.B]

Yeah with the hose off.
I still have no clue if mine works right or not but if this thread leads to a resolution it would be awesome.

I know what you mean, I've had this problem for so long, and have never been able to figure it out.

In regards to the battery reset solving the issues for a bit, would this explanation make sense:
There is a bad sensor and/or connection, and in the same way when you install a chip, it takes a bit for the ecu to "learn the chip" in this case the ecu is "learning" a bad sensor? So at first it send proper information, as its supposed to, bad as it receives the feedback from the bad sensor/connection it begins to adjust?

Sorry guys, I'm no pro, just trying to think this through.

[Lucas.B]

OK I just took the numbers right after reseting the ecu (also charged the battery) and I'm getting this on the harness going into the ICV:

Centre + Right Side = ~10 V (Just what the Haynes says)
Centre + Left Side = ~4 V still

Could I be onto something here, are they not both supposed to be about 10?

Thaks guys

[nando]

it's a pulsed voltage signal.. the reading you get could vary by how fast/sensitive your DMM is. I wouldn't put too much into that reading, as long as you are in the ballpark +/- 1-2v the DME is sending the right signal.

the valve is supposed to buzz with the ignition on. Most likely it's just gummed up. Putting in a chip doesn't have anything to do with the ICV, to my knowledge none of them actually modify the idle code (no reason to). It probably runs a PID loop so pretty much you can throw anything at it (cams, chip, compression, etc.) and it will still idle the engine like stock, unless something is broken.

[Lucas.B]

it's a pulsed voltage signal.. the reading you get could vary by how fast/sensitive your DMM is. I wouldn't put too much into that reading, as long as you are in the ballpark +/- 1-2v the DME is sending the right signal.

the valve is supposed to buzz with the ignition on. Most likely it's just gummed up. Putting in a chip doesn't have anything to do with the ICV, to my knowledge none of them actually modify the idle code (no reason to). It probably runs a PID loop so pretty much you can throw anything at it (cams, chip, compression, etc.) and it will still idle the engine like stock, unless something is broken.

Hey thanks

I meant the chip thing as an analogy, my car has stock everything, i meant in in that like a ecu takes time to learn a chip, my car is learning a bad sensor and reacting to it, thus getting a perfectly running car upon reseting the ecu, and it slowly showing symptoms of the bad sensor.

Sorry if that makes no sense

[Adrian_Visser]

i don't know if i agree with your logic on the ecu learning to correct for faults though, i would think that the engine would run worse just after resetting and would get better over time as the ecu learned to correct for the fault. that makes more sense to me, i'm no expert though.