My 2.8 seems to idle much better when I have the IAC closed and unplugged. I've only had it in this condition when I have the ECM in diagnostic mode, so it doesn't set a code.

Is there any way to disable/unplug/remove the IAC motor assembly so that my idle is set by the throttle blade, instead of by a computer???

Thanks!

 

most obvious answer, & one your anxiuosly waiting on: Why not jut clean/replace IAC?

next one: how would it be adjusted not totally mess w/ the TPS?

 

IAC is clean. Almost tongue-proof... I don't see how the IAC and TPS are mechanically connected? With the paperclip installed, and the IAC closed and unplugged, my idle is MUCH smoother, which seems preferable to me. I'm just wondering if there is a way to 'jump' out the connector, so that the ECM does not set a code...

 

the tps is conected to the throttle blade bar. that's what I meant.

 

Well, I have the throttle blade set for an idle of around 5-600 rpm, and in that position, the TPS is at +.554vdc. It idles great in that condition with the IAC closed and unplugged.

 

Wow, man, no offense, but why do some kind of rig job on your car? Once you start disabling systems and screwing with the idle speed, yeah you might get a car that runs, but wouldn't you rather fix it the right way?

I tend to believe your problem isn't related at all to the IAC or TPS. Have you checked (probably better to replace) the distributor module and/or pickup coil? Timing chain? Fuel pump, both pressure and volume? What about fuel injectors, are they in balance? Any leakers? Fuel pressure regulator working properly? CTS okay? MAF okay? Oxygen sensor okay? And by "okay", I mean giving the computer a value that's valid? My CTS could be 20 degrees off but the computer will think it's just 20 degrees colder outside... know what I mean? A MAF can go bad and still not throw a code. Vacuum leaks? Brake booster check valve leaking? Have you checked the vacuum with a gauge at all? How's the compression? EGR sticking? Leaks after the throttle body, like, at the TB-to-plenum connection or upper-plenum-to-lower-plenum connection? Leak at the EGR-to-plenum? Alternator voltage low or high? Power steering pressure switch working as it should? Heat range and gap of plugs correct? Have you read the plugs yet, are they fine? Throttle blades sticking (throttle hard to work)? Swapped ECM's for a junkyard one, using your car's chip in it? Leaks in the exhaust, including at the exhaust manifolds? Do you have a Win95 laptop? You could make the free diagnostic cable and run WinALDL while your car is running to look for "bad" sensor values.

 

damn tom, i love you man

how do you do that win95 laptop thing??? where do you get the program? how do you make a free cable? how do you use it? thanks man:hail:

 

Have you ever adjusted your idle speed?

 

Yep.

TomP: WOW, that's one hell of a list you got there...

The plugs, wires, cap, rotor, TPS, coil & O2 sensor are new. Everything cleanable is clean. I guess I will take a look for vac leaks next...

This cable and software you speak of... Can you give more detail? This sounds like a good companion to my OBDII scanner...

Thanks!

 

LOL, squirrelybird! I just tried to think of every damn sensor in the engine compartment. BIBGP's car might be running better without the IAC because of a faulty sensor that's putting the computer into some kind of limp mode, so I just tried to think of everything.

Plus, BIBGP, my car has a stuck-open injector right now... likes to die as soon as I start it- if it's cold out. So I start it again, and the rpm's go Waaaay up, then it stalls. If I play with the gas, it'll stop from stalling, but until it warms up, the rev's will drop to nothing, then go realllly high on their own. So I wonder if it's something related to fuel or spark that might be causing your car to think it's stalling.

Info on the winaldl cable can be found here: https://www.thirdgen.org/techbb2/sho...hreadid=132831

Here's another:
https://www.thirdgen.org/techbb2/sho...hreadid=120634

I gotta split to meet the fiance but basically if you search the DIY PROM burner's board you'll find info on Winaldl. And a few guys here have made the cable too. There's even a DOS software I remember floating around... I gotta dig it up and try it, because my old 386sx16 laptops (bought 'em each for $50 about 5-6 years ago) can barely run Win3.1! 'Fact, check out the top message on this board about the seroius prom burners, there's info on winaldl in there too.

 

or go here www.winaldl.webhop.net and get the real deal from the guy who wrote it.

 

OK, so I spent the weekend checking things under the hood...

Everything *appears* to be fine, all of my vac lines are in great shape... If I jam the paper clip into the diagnostic port, and turn the ignition to run, wait 45 seconds, and unplug the IAC, then start the car, it idles GREAT...

If I re-enable the IAC, and pull the paperclip, start the engine for 5 seconds, then odd for 10, then start again (to re-learn the IAC position), the idle is too high again, and hangs high again (here is the thread on THAT problem... CLICK HERE)

Any new thoughts? How do I test the vacuum check valve on the back of the intake manifold? Sluggish IAC motor? I've cleaned the IAC motor externally, should I disassemble it, or just replace it?

 

have you broken out a multimeter & checked the AIC wires for shorts?