high idle after lim & uim change! HELP!!!

[lvbroham1]

alright, here's my story... I have a 95 Z34 About 3 months ago I was driving home from school going down a hill and the car shut off on me. Luckily I was able to get it to the side of the road, anywho... I tried starting the car and it would just crank and crank with no fire, all the electronics worked so i figured it wasn't electrical. I know some about cars and figured it was the fuel pump. Along with the fuel pump I had that distributor oil leak thing that needed some long overdue attention, I decided to also tackle this to get rid of little puddles of oil in my driveway. After replacing the oring and seeling it up, I installed new lim gaskets and uim gaskets, fuel injector orings, valve cover gaskets, both egr gaskets, replaced the booster hose, replaced iac, starter, and replaced pcv valve. I start it for the first time and get an idle around 2700-3000rpms. I only let the car run for about a min, as I thought it was unsafe to let the car idle like this. I also put it in drive and reverse and the idle dropped, but the car still felt like it wanted to take off and the idle was still unusually high. The idle seems the highest in park and neutral. I've read other posts and it sounds like I have a vacuum leak, but where? Am I missing something? I just replaced all the gaskets on this thing. Sorry for the length, any help is greatly appreciated
-Martin

[markmead]

High Idle

I know it may be a bit late for this post, but from what I remember that car may need to re-learn it's idle, after the work you have done (more specifically disconnecting the battery). I know you can do this with a Tech 2 scan tool, but believe it can be done by starting the car and leaving it in gear for 8 to 10 minutes (unsure of the exact details, but know a process for this does exist).

Hope this helps,

Mark

[walterdude]

OBD1 Idle Re-Learn Procedure:
http://60degreev6.com/content/Idle_Relearn
Tom

[lvbroham1]

OBD1 Idle Re-Learn Procedure:
http://60degreev6.com/content/Idle_Relearn
Tom

I will try this right now and let you know the results in a little bit. Thanks for the quick responses!

[lvbroham1]

tried the idle return thing, and no bueno. I'm going to wait till the wind calms down and start looking for leaks wiyh carb cleaner. I've replaced all the worn vacuum lines and hard pcv hoses. When I spray carb cleaner in the gasket areas, should the idle go up even more, or should it go down if there's a leak? I'm thinking this should be a two person job, so that I don't leave the car idling at 3-4,000rpm while i'm under the hood. The car sounds strong, a little smoke from all the finger prints and simple green. i'm thinking maybe i should"ve done the L67 swap instead lol

[55trucker]

I might suggest that before you go searching for vacuum leaks rule out the possibility that the new IAC motor you installed is not closed/closing. Without the Tech 1 tool you might try removing the motor again from the plenum, with the harness still attached, key on/ key off to see if the pintle is moving at all. With the harness disconnected the pintle arm can be carefully extended with your fingers so as to close off the idle passage in the housing. If you reinstall the motor again with the harness now disconnected and left disconnected and the idle passage is blocked the engine should not start when you turn the key. If it does fire then air is getting in from somewhere else. (note that the harness disconnected from the IAC Will set a code). With the air snorkel removed can you see if the throttle blade is fully closed?...

[lvbroham1]

ok, i will try this now and let you know the results.

[lvbroham1]

ok, so i just did the whole key off, key on thing, and the IAC is not moving at all. So now I should pull on it to extend it? It seems like it's letting air in and not regulating it... I will try to pull it out a little and see if it solves the problem, if not, i'll do the whole disconnect from harness and see if it starts. thanks for point out that it might not be working, i would've never thought to look at it being that it was new and all.

[lvbroham1]

ok here's a pic of the IAC. It seems to be open and stuck that way. I pulled on it a little, but it feels like it might break if I pull any harder. i'm a little confused as to why it wouldn't be working

[walterdude]

Well this what Haynes (somewhat edited) has to say about replacing the IAC.... This is the process I used when I replaced the IAC on my 93 Z34.... It worked for meE!!!
Hope this helps....
Tom....
It says NOT to push or pull the pintle,,, it could damage the threads on the worm-drive...


"-Before installing a new IAC valve assy, the position of the pintle must be checked.
-Measure the distance from the gasket mounting surface of the IAC assy to the tip of the pintle.
-If the distance is greater than 1 1/8" reduce it by applying firm hand pressure on the pintle to retract it.

Note: the IAC resetting is controlled by the ECM. To initiate this process turn the ignition on for 5 seconds,,, turn it off for 10 seconds,,, then start the engine and check for proper idle..."

[55trucker]

There will be resistance to your attempt to manually move the pintle....the motor & pintle arm is a worm gear design.....here's where some voltage applied to the motor is needed to move the arm.... you can see in the wiring diagram that the control is a double pole double throw application that moves the motor. You have applied voltage in one direction for both circuits that moves the pintle in one direction and to reverse the direction the voltage is reversed. You can literally do the same with a low voltage applied to the motor contacts to get it to move. This particular circuit is so much easier to diagnose if one has access to a scan tool ....but that's something we don't all have in our back pocket..

[55trucker]

I did come across another note in my Chiltons manual (the GM manual is rather rigid and not always as flexible as the after market)....*Quote......No physical adjustment of the IAC valve assembly is required after installation. The IAC valve is reset by the ECM when the vehicle is driven at a speed ABOVE 30mph or when the diagnostic test terminal is grounded while the engine speed is above 2000 rpm*.....I had to dig this manual out (I don't use it too much)...but there's another route you can try to see if the IAC is actually working.

Steve

[lvbroham1]

ok, i played with it a little before sundown. I took my old sensor and put it in when it was fully extended, the car wouldn't start, so i'm guessing I don't have a vacuum leak. I did the reset thing about 4 times and no luck, so tomorrow I will take her out for a drive and see if this settles the whole idle issue. I appriciate all the help guys, and i'll let you all know if this works or not tomorrow.

[lvbroham1]

alright guys installed a new IAC and verified that it worked, took the car for the first drive after the fix, and the idle is still very high. I think i heard somewhere that there's a senor for the power steering and transmission that adjusts the idle? I've canceled out a vacuum leak at the uim and lim, the IAC works, the throttle blade isn't stuck, and all vacuum hoses and such have been replaced like I stated before. Maybe the tranny or ps sensor could be bad? Do these sensors regulate idle or was I reading some bs? I'm open to any suggestions at this point.

[lvbroham1]

and in addition... i realy appriciate all the help so far