How to check if IAC works C950
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Joined: Feb 2000
Posts: 1,170
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From: Seattle, Washington
Car: '87 IROC-Z/'82 RX7
Engine: SBC 355/1.1L Rotary
Transmission: T56/5 Speed
Axle/Gears: 4.33/3.93
How to check if IAC works C950
I've got a lean condition as I've posted about several times.
So far it's been narrowed to the intake gasket. Today talking with my professor in school, he suggested the IAC wasn't working, maybe stuck open or not getting the proper input.
How do I check the IAC?
The throttle body is relatively new, Holley 58mm, and I don't recall if I've ever replaced the IAC in the 3 years I've owned the car.
So far it's been narrowed to the intake gasket. Today talking with my professor in school, he suggested the IAC wasn't working, maybe stuck open or not getting the proper input.
How do I check the IAC?
The throttle body is relatively new, Holley 58mm, and I don't recall if I've ever replaced the IAC in the 3 years I've owned the car.
Thread Starter
Supreme Member
Joined: Feb 2000
Posts: 1,170
Likes: 0
From: Seattle, Washington
Car: '87 IROC-Z/'82 RX7
Engine: SBC 355/1.1L Rotary
Transmission: T56/5 Speed
Axle/Gears: 4.33/3.93
Found out how to check on another forum. Cover the idle air hole and see if the idle goes up/down etc.
I was also told that you can't have a vacuum leak with MAP, by definition.
Somehow the engine is getting more air. I drove the car for 4 weeks straight daily because my Jimmy was down. One night two poly locks broke off. #5 exhaust and #2 intake.
After I replaced the locks.... the O2 mod read about 110 everywhere idle and cruise. I added more fuel in the lean cells and it got better. Still slightly twitchy a low Map (high vacuum) areas.
I checked plugs after this tune change, and they showed perfect, heat strap right on the apex of the electrode. I set the tune back to the lean tune (which was beautiful before the polylocks broke) and checked the plugs again. The heat strap was much closer to the threads than before, almost touching.
Somehow this thing is getting more air. I've checked all the vacuum lines I can and found nothing. I am going to buy a vacuum pump gauge to check the components idividually. Checked base timing, checked alternator, checked grounds, fuel pressure. Yet to check Cap/rotor though they are newer. My best guess is that the intake manifold gasket went under the stealth ram to the lifter valley... but several plugs show lean, not just one.
If there is no vacuum leak with MAP, why am I lean? And it's not just when in closed loop, it made my cold temps pretty bad too. Poppy and sputtery.
I was also told that you can't have a vacuum leak with MAP, by definition.
Somehow the engine is getting more air. I drove the car for 4 weeks straight daily because my Jimmy was down. One night two poly locks broke off. #5 exhaust and #2 intake.
After I replaced the locks.... the O2 mod read about 110 everywhere idle and cruise. I added more fuel in the lean cells and it got better. Still slightly twitchy a low Map (high vacuum) areas.
I checked plugs after this tune change, and they showed perfect, heat strap right on the apex of the electrode. I set the tune back to the lean tune (which was beautiful before the polylocks broke) and checked the plugs again. The heat strap was much closer to the threads than before, almost touching.
Somehow this thing is getting more air. I've checked all the vacuum lines I can and found nothing. I am going to buy a vacuum pump gauge to check the components idividually. Checked base timing, checked alternator, checked grounds, fuel pressure. Yet to check Cap/rotor though they are newer. My best guess is that the intake manifold gasket went under the stealth ram to the lifter valley... but several plugs show lean, not just one.
If there is no vacuum leak with MAP, why am I lean? And it's not just when in closed loop, it made my cold temps pretty bad too. Poppy and sputtery.
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