1985 Corvette setting the idle SOLVED
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,460
Likes: 48
1985 Corvette setting the idle SOLVED
Hello everybody,
First I want to thank everyone that made an effort to help me. Early on in the work on this car I discovered that the gasket in the air horn of the TB unit was NFG. So I traced it and made a new one. Evidently, when I did that I did not make the opening for the IAC. My mechanic was removing the IAC and broke it. It is the original so something like that is to be expected. He an the car with the IAC out and realized that there was no sound of air rushing through the IAC portal. He took off the TBI unit and discovered the problem. The car now idles very well and the IAC is down to 17 counts. Thank you all
First I want to thank everyone that made an effort to help me. Early on in the work on this car I discovered that the gasket in the air horn of the TB unit was NFG. So I traced it and made a new one. Evidently, when I did that I did not make the opening for the IAC. My mechanic was removing the IAC and broke it. It is the original so something like that is to be expected. He an the car with the IAC out and realized that there was no sound of air rushing through the IAC portal. He took off the TBI unit and discovered the problem. The car now idles very well and the IAC is down to 17 counts. Thank you all
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Hmmm I just reread your earlier posts. So the high IAC count and the high MAF reading were all because of the home made gasket that blocked the idle air passage correct?
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,460
Likes: 48
I hope it does. I new the problem was air related. But, I had 20 inches of vacuum. Well we have all been there and done that.
i was working in a garage the guy next to me was doing his brakes. He pumped the pedal and the rear drums were not on the car.
I told him we all have done something like that. Comes with the territory.
In any event. Thank you for the help.
Have a great father's day
i was working in a garage the guy next to me was doing his brakes. He pumped the pedal and the rear drums were not on the car.
I told him we all have done something like that. Comes with the territory.
In any event. Thank you for the help.
Have a great father's day
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
I hope it does. I new the problem was air related. But, I had 20 inches of vacuum. Well we have all been there and done that.
i was working in a garage the guy next to me was doing his brakes. He pumped the pedal and the rear drums were not on the car.
I told him we all have done something like that. Comes with the territory.
In any event. Thank you for the help.
Have a great father's day
i was working in a garage the guy next to me was doing his brakes. He pumped the pedal and the rear drums were not on the car.
I told him we all have done something like that. Comes with the territory.
In any event. Thank you for the help.
Have a great father's day
Fathers day is first first Sunday in September in Australia so I have a little wait, but you enjoy yours.
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Oil Producer
Joined: Apr 2014
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Well usually you see the same root causes over and over. Since I’ve been here, which granted is not that long, I’ve never seen anybody block off their own iac port With a homemade gasket! I’ve been known to make a couple homemade gaskets out of Fel-Pro material and cork material, so it’s a good heads up for me to double check the work
Melting Slicks
Joined: Aug 2003
Posts: 3,394
Likes: 393
From: Lakeville MI
Hang on. Its good that the IAC is now functional, but If the IAC is currently at 17 counts at 1,000 rpm when scanning in ALDL mode, it can only drop to zero in an attempt to control to the desired idle rpm (typically 650-700 rpm for manual trans cars and 550-600 rpm for autos).
I would expect the idle to hang high around 800-850 rpm with the IAC at zero counts, with the ecm unable to control idle to the desired idle rpm. I think you will need to go back and readjust the tps and throttle screw in order to regain control.
I would expect the idle to hang high around 800-850 rpm with the IAC at zero counts, with the ecm unable to control idle to the desired idle rpm. I think you will need to go back and readjust the tps and throttle screw in order to regain control.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,460
Likes: 48
Viking Trad3
Exactly what I told him. He worked very hard on this. I felt very bad. I was positive I had copied it exactly. Doh!
Tequilaboy,
Hang on. Its good that the IAC is now functional, but If the IAC is currently at 17 counts at 1,000 rpm when scanning in ALDL mode, it can only drop to zero in an attempt to control to the desired idle rpm (typically 650-700 rpm for manual trans cars and 550-600 rpm for autos).
The car is a manual.
I would expect the idle to hang high around 800-850 rpm with the IAC at zero counts, with the ecm unable to control idle to the desired idle rpm. I think you will need to go back and readjust the tps and throttle screw in order to regain control.
Yes, you are correct we discussed that last night. Not that we have a steady idle. We will be readjusting the MAF, the idle, TPS and the timing.
Thank you all. Have a great Father's Day
Exactly what I told him. He worked very hard on this. I felt very bad. I was positive I had copied it exactly. Doh!
Tequilaboy,
Hang on. Its good that the IAC is now functional, but If the IAC is currently at 17 counts at 1,000 rpm when scanning in ALDL mode, it can only drop to zero in an attempt to control to the desired idle rpm (typically 650-700 rpm for manual trans cars and 550-600 rpm for autos).
The car is a manual.
I would expect the idle to hang high around 800-850 rpm with the IAC at zero counts, with the ecm unable to control idle to the desired idle rpm. I think you will need to go back and readjust the tps and throttle screw in order to regain control.
Yes, you are correct we discussed that last night. Not that we have a steady idle. We will be readjusting the MAF, the idle, TPS and the timing.
Thank you all. Have a great Father's Day
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Well usually you see the same root causes over and over. Since I’ve been here, which granted is not that long, I’ve never seen anybody block off their own iac port With a homemade gasket! I’ve been known to make a couple homemade gaskets out of Fel-Pro material and cork material, so it’s a good heads up for me to double check the work
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,460
Likes: 48
So I really do feel the need to comment on the lack of haters. it is appreciated. Believe I feel awful that I did this. On FB and other social sites there are so many rude and judgmental people. Thank you all.
Have a great Father's Day.
Once the car is off jack stands I will post some pictures.
Have a great Father's Day.
Once the car is off jack stands I will post some pictures.
