IAC Valve removal?

[shr3dd3r 09]

So I tried driving around with the IAC electrical plug disconnected, and I still have surging idle and rpm spikes when depressing the clutch. It was better for a while but not enough to make any real difference. This is with using an auto PCM with a manual tranny.

It is starting to get ridiculous to drive this thing. The problem has only gotten worse. I drove home from dinner today in 4th gear and didn't have my foot on the gas, and when I depressed the clutch it would idle at 4000 rpms. It's like it cycles between idling at 3000+ rpms and 300 rpms. Both of which are unacceptable. I am not driving it like this any more for fear of burning my brakes up or killing myself.

So, in the meantime before I have the PCM tuned to hopefully get rid of this annoyance, can I solve my problem by removing the entire IAC and covering the holes (preferably a gasket, but for now duct tape )? Then I can just adjust the idle manually with the TB screw.

Or is the PCM too smart for this? It would seem to me that it would have no choice but to idle at a constant speed. But that's what I thought would happen when I disconnected the electrical plug...boy was I wrong.

 

[allnpt0]

Did you pull the codes in the PCM? That may tell you what you need to do. Blocking the IAC won't help. The PCM controls the IAC and injector pulse width as well as ignition timing. Bumping the idle screw will make a mess of everything. Just hold off driving until you get the PCM flashed. My .02.

Pete

 

[shr3dd3r 09]

Did you pull the codes in the PCM? That may tell you what you need to do. Blocking the IAC won't help. The PCM controls the IAC and injector pulse width as well as ignition timing. Bumping the idle screw will make a mess of everything. Just hold off driving until you get the PCM flashed. My .02.

Pete

I wanted to drive it around for a few days to see what problems I would have. The idle speed and auto tranny CEL's seem to be the only issues really, otherwise it drives fine provided the TB screw isn't overly "adjusted." Guess I'll call and see about pricing for a tune.

 

[Teddyzee]

The idle screw simply opens or closes the throttle body. There's nothing to really "screw up", you're not likely to move it enough to put the TPS sensor out of range, although it is certainly worth checking.

 

[bearsrngr]

Also make shure the IAC is not flipped 180deg like mine is currently (not by choice). Engine vacume can pull it open causing high idle when unplugged. Mine will idle @ about2500 unplugged, it works OK plugged in but does hunt a little when first started. I will pick up and try a SN95 IAC some time before spring, that hopefully will solve the surge.

 

[shr3dd3r 09]

View attachment 9064Also make shure the IAC is not flipped 180deg like mine is currently (not by choice). Engine vacume can pull it open causing high idle when unplugged. Mine will idle @ about2500 unplugged, it works OK plugged in but does hunt a little when first started. I will pick up and try a SN95 IAC some time before spring, that hopefully will solve the surge.

It isn't flipped. Mine idles at about 2700 now until it warms up. And for that period of time it is putting out enough power to pull itself 45 mph in fourth gear with my foot off the gas... which is awful driving in traffic.

After warming up it will idle at about 1000 and is much easier to drive, but after idling like this for a few minutes the rpms drop so low it will die unless I step on the gas. In any case I'm having the PCM flashed Monday so it will hopefully run like it should with the manual transmission. Not driving it anymore until then, it will only frustrate me...