Quick Couple of Questions

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Evilcowboy420

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Ok so I did a TBI rebuild. The only trouble is after putting everything back together the car won't idle right and won't start until you press the gas a bit.

I am suspecting the IAC valve to be closed. I didn't want to touch the minimum idle screw cause these come set from the factory.

So I disconnected the battery negative and am going to check it out tomorrow. I am hoping this resets the ECM and will get it to start. I am thinking the ECM has a bad value stored for it to compensate for the crappy stuff that was on there. After the rebuilt I think it threw it off trying to run with the stored value.

So my questions. How long does it take to reset the ECM? How many times should the CEL flash to indicate the ECM was successfully reset? Is there anyway to verify if the IAC Valve is actually working properly (ie: pulling it and watching to see if the pintle moves up and down.) And what is the proper procedure to reset the idle? And what RPM range should this old car idle at (I have a paper that came with the rebuild kit telling me 600 but that sounds a bit on the low side)

Any help nailing this down is appreciated.
 
EC, I heard you have to turn the key on for 20 seconds than off for 10 to reset the IAC.

You can take it out and turn the key on and off to see if the pintle is moving back and forth.

Mine was still moving so I didnt buy one yet.

For the computer to go back to regular mode , about 2 1/2 to 3 days.

Its in limp mode till then.

Ill try to find the links for the info.

Doug in P.R.:cool:
 
Did you change the injector(s)? ( Its known to get bad brand new one like starters and altenators.... have to get a few to get a good one)

Doug in P.R.:cool:
 
Last edited:
http://www.gmtuners.com/tech/TPS_IAC.htm

http://www.gmcmidwestclassics.org/Web pages/Tuning the TBI.pdf

http://www.a-body.net/forums/showthread.php?5869-Setting-IAC-(Idle-air-control)-valve


Takes a while to relearn is what I'M reading ........................:)

CHECK ENGINE LIGHT
You should always have a code 12 ( one flash- 2 flashes if there are no codes)

Trouble codes come after the code 12 if you have problems.

Doug in P.R.:cool:
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yep it wouldn't stay started and idling right so I did the following

Turned the key on then off
wait 30 seconds
unplugged IAC valve
adjusted the screw for minimum idle to sound right
started and tweaked the screw
turned off
plugged IAC valve back in and started.

This was the procedure for a minimum idle adjustment.

The IAC valve worked I tested and was moving.

I didn't replace the injector and it is working since turned the key while looking at it to watch the stream coming from it to confirm it worked.

I imagine the tps was fine as well

My guess is the IAC adjusted for vacuum leaks to a full closed position. When it was repaired the car still thought it was screwed and didn't allow the car to start.

Now I just wished I didn't have to touch that screw but I simply was not going to get it started without holding down the gas pedal to start it.

I did mark where it was originally so when I have 2 to 3 days I'll move it back and do the idle relearn.

But I did go to the junk yard and spent 18 bucks for a new IAC, TPS but I haven't installed the tps.

But everything from the head up is brand new so its probably just needs to relearn itself.
 
Ok doug got a chance to go through those links. They have some great info in them. The whole thing about grounding the ALDL I wasn't getting until I saw the PDF with the jumper wire between the black and white wires (in mine these are black with white stripe and white with black stripe). After jumping it the CEL was flashing all sorts of stuff at me and I followed the procedure to the letter. You could tell this worked. I also liked that it made me feel better since it explaines if you do a modification or a rebuild this will need to be done.

Thanks a ton for those links they helped a great deal.

Now I just gotta wait the 2 1/2 to 3 days for it to relearn it all.

Oh and drove it all day no CEL but there were times it would stall and would not start without a touch on the gas pedal which I am guessing it is just trying to relearn the whole thing so I will post if everything is back to normal in a few days.

Now I was curious if the whole IAC could be bypassed not that I am going to do it or anything . But the engine can be cranked and the idle can be adjusted. I am curious if the car could run that way kind of making it an old school type carb. Just a passing thought. I know gas economy is going to be at its best with the IAC but just wondered if it could be done without adverse effects. lol

Anyways thanks again Doug.
 
Your welcome, Dont ask me about the Check Engine Light on my car cause I pulled the Bulb when I bought it...................................:D


Might have to put it back in if I get into some big trouble...............:D

A paper clip is the tool to use to check your codes, I did have one made out of flat metal that came with a code book that I got from Autozone when they first came to the Northeast.( before the internet days lol)


OOHH NOO I'm dating myself......................................:D

No problem looking up stuff, I have some free time everyday since no house building stuff to do in the last couple of weeks, but then thats a long story:eek: Starting back up next weekend...............:)

Doug in P.R.:cool:
 
Evilcowboy420 said:
.

Now I was curious if the whole IAC could be bypassed not that I am going to do it or anything . But the engine can be cranked and the idle can be adjusted. I am curious if the car could run that way kind of making it an old school type carb. Just a passing thought. I know gas economy is going to be at its best with the IAC but just wondered if it could be done without adverse effects. lol
Click to expand...

While I was having stalling/low idle problems , I turned in the idle screw all the way to keep it idleing. When I fixed it it idled higher so I just backed up the screw as close to original distance it was. ( spring loaded)

Turned the key and it idled like the IAC would but it was way passed where the IAC would do it .(overided the IAC- using the TPS as a idle)

Not sure you can do that on the Throttle Body setup.....:confused:

Doug in P.R.:cool:
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hmmm yeah that screw is the same on mine spring loaded as well. I got it turned a bit more than it was because after doing the whole rebuild it would not stay started lol. She's not very happy with not having any vacuum leaks I guess lol.

But after the reset and every thing she was still throwing the code so I cleared the ECM and waited for the code again. I then jumped the pins and read the codes. The only code it is throwing is 32 stuck EGR valve. So I checked it and sure enough it was stuck. I manually depressed it and got it unstuck. I guess I didn't clean it out as good as I thought that little pintle inside is hard to get at.

So to check the EGR a bit further I took it off and depressed it and put my finger over the hole and it went back to closed position. I have had some people tell me that while your finger is over the hole the valve should not close but it should stay open. So I guess its shot but being a bit on the expensive side its gonna be Ebay for me to get that.

But I have heard people say if the IAC is working and after a few days it don't improve replace the TPS or adjust it. But I don't think it is adjustable. I do have the spare around so if it don't improve I will pop that sucker on. But it did appear it was working when I checked it with a multimeter.

Who knows I just know I confused the shit out of the computer.
 
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