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JUST TRYING TO HAVE FUN!
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Discussion Starter · #1 ·
I have had an ongoing problem with my 87 Grand National. One day I went out and started it up and the idle shot up to 2,500-3,000RPM and won't come down....I was told by a friend who works at Pepboys that a mechanic there said it was my IAC ...so I replaced it and that seemed to solve the problem for about a week and then the same problem was back???? So I spoke to another mechanic and he too said it was the IAC....or the chip..... when I told him I replaced both things...... he told me to disconected the wire that runs from the battery to the computer to reset the computer....and that seemed to work for about a week?? Now the problem is back.....So I disconnected the wire again and it does not solve the problem this time....I NEED HELP ON THIS ONE BAD!!! Could it be the computer itself ?? and if so how do I check that?? ANY HELP WILL BE GREATLY APPRIATED!!
 

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Aw, don't give up after that!! You've probably got 30 other things that will make you think like that coming your way eventually with the car. But always remember how it's gonna feel when you mash the throttle once you DO get it running right! powersix yup

You can probably pick up another ECM (computer) to swap in for a decent price, and see what that does for ya. But hopefully someone else here has had more experience troubleshooting these things, rather than just throwing parts at it and hoping for the best. Given what you described, it must be something else besides IAC, because I can't see what could wipe a new one of those out so quickly.??? You get the SES light at all? If so, see what codes it has stored. That should also tell you if the ECM is working or not. That's what they were getting at by unhooking the power and resetting the ECM. Good luck, it will be worth it. wink
 

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http://www.gnttype.org/techarea/faq/IACreset.html

There is a good chance you need to set the tps idle, and wot voltage. I included a link for the iac resett procedure so you can do that after setting the tps.

Since I tune with a scanmaster I can't tell you wich wire to probe for thoose voltages. I believe there is a 5 volt reference wire, the variable voltage line, and ground?.

If you go to www.gnttype.org you can do a search for malfunction codes, use control-f on your computer, type in the word idle, and find all the codes that are indicated by a high idle.

14, and 21 come to mind, there might be a couple more.

If you own one of these cars, you need a scan tool to help find problems. The high idle shouldn't be too hard to find.

Anybody been playing around with the air bleed screw? That will do it. one and a half, to two and a half turns from completely closed is where mine is set.

Here is another link for you to check out..

http://www.gnttype.org/techarea/

And the malfunction codes...

http://www.gnttype.org/maint/malf.html

<small>[ April 15, 2003, 07:43 PM: Message edited by: Turbo_Tim ]</small>
 

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JUST TRYING TO HAVE FUN!
Joined
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667 Posts
Discussion Starter · #4 ·
I would like to THANK YOU GUYS! I went to the web sit you told me about Resetting the IAC, and it seems to be working. It is back to a normal idle :D Should I expect this to happen again or now that I reset it will it be O.K.? As you can see from my log-on name, I am a mopar man and these G.N.'s are new to me...Have always loved them,but could not afford them at the time. Thanks again for the help! :)
Turbo_Tim:
http://www.gnttype.org/techarea/faq/IACreset.html

There is a good chance you need to set the tps idle, and wot voltage. I included a link for the iac resett procedure so you can do that after setting the tps.

Since I tune with a scanmaster I can't tell you wich wire to probe for thoose voltages. I believe there is a 5 volt reference wire, the variable voltage line, and ground?.

If you go to www.gnttype.org you can do a search for malfunction codes, use control-f on your computer, type in the word idle, and find all the codes that are indicated by a high idle.

14, and 21 come to mind, there might be a couple more.

If you own one of these cars, you need a scan tool to help find problems. The high idle shouldn't be too hard to find.

Anybody been playing around with the air bleed screw? That will do it. one and a half, to two and a half turns from completely closed is where mine is set.

Here is another link for you to check out..

http://www.gnttype.org/techarea/

And the malfunction codes...

http://www.gnttype.org/maint/malf.html
 
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