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Well I’ll be dammed I just looked under the hood and sure enough the idle air control plug was loose and I pushed it back in def ordering a new one I’m going to check on this more often but I do believe that might be it
A loose IAC can cause it to stall but im not sure how a loose IAC would cause the idle to hang. Maybe since the connection is intermittent the ecu is trying to command more iac since its responding intermittently?
 

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If the idle is hanging, it sounds to me like some sort of vacuum leak. I may have missed it, have you done a smoke test? Im helping a friend build a 331 and he pulled his old motor apart a couple weeks ago. The car never ran right and I wanted him to do a smoke test but he never got around to it. After pulling the upper intake manifold, we found the intake gaskets were cracked/ripped on most of the runners. The car had a serious vacuum leak all the time which explains the weird way it ran. Ive never seen an intake gasket ripped/cracked across all cylinders before but it just goes to show you. Issues can be hiding where you cant see them.

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:oops: sheesh
 

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Discussion Starter · #64 ·
If the idle is hanging, it sounds to me like some sort of vacuum leak. I may have missed it, have you done a smoke test? Im helping a friend build a 331 and he pulled his old motor apart a couple weeks ago. The car never ran right and I wanted him to do a smoke test but he never got around to it. After pulling the upper intake manifold, we found the intake gaskets were cracked/ripped on most of the runners. The car had a serious vacuum leak all the time which explains the weird way it ran. Ive never seen an intake gasket ripped/cracked across all cylinders before but it just goes to show you. Issues can be hiding where you cant see them.

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If this idle air control connector I guess I’m going to pull the lower intake manifold off I already have new gaskets because I just powder coated my upper intake and I never took off the lower but I did already do a smoke test and I did not see any leaks even after a good few minutes of letting the smoke machine run and it was in fact working as it should and I put it in the throttle body oil cap sprocket thing on top
 

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Discussion Starter · #65 ·
Read this link about code 63 post #6 and what jrichker wrote and the diagrams he posted.
So I’ve already cleaned and split the 10 pin connectors on my car a few weeks ago and it didn’t seem to make a difference but I zip tied my idle air control valve connector in place so I’ll be watching it to see if that change’s anything
 

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Discussion Starter · #66 ·
Read this link about code 63 post #6 and what jrichker wrote and the diagrams he posted.
Okay so I drove it to work today and it ran perfect after I zip tied the connector in place but I turned it off and started it and the idle got hung for a second and I had to stop it and restart it again and it ran perfect whole way home
 

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Discussion Starter · #68 ·
How old is the throttle body? Is there a ridge inside the throttle body in the aluminum around where the butterfly rides when it's closed at idle?
It is the factory throttle body and I can look todsy when I get off work I thought about getting new throttle body and egr spacer for my car because I was thinking maybe the factory throttle body is causing issues
 

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Yeah over time the brass butterfly may cause a ridge to develope in the aluminum radius on the inside of the T-body housing causing idle issues/hanging idle issues. Seen it on t-body's with lots of mileage. Seen it on t-body's that were never cleaned and dirt and grime build up in there and a ridge develope's. Also seen it happen with boosted water/ methanol set ups when the inside of t-body gets corroded and dries out and friction going on develope's a ridge inside there.
 

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Discussion Starter · #70 ·
Yeah over time the brass butterfly may cause a ridge to develope in the aluminum radius on the inside of the T-body housing causing idle issues/hanging idle issues. Seen it on t-body's with lots of mileage. Seen it on t-body's that were never cleaned and dirt and grime build up in there and a ridge develope's. Also seen it happen with boosted water/ methanol set ups when the inside of t-body gets corroded and dries out and friction going on develope's a ridge inside there.
So I drove the car today and it ran like **** so I unplugged the iac to try and adjust the throttle screw and I couldn’t get it to run smoothly with the iac unplugged but it would run but terribly
 

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Discussion Starter · #71 ·
Yeah over time the brass butterfly may cause a ridge to develope in the aluminum radius on the inside of the T-body housing causing idle issues/hanging idle issues. Seen it on t-body's with lots of mileage. Seen it on t-body's that were never cleaned and dirt and grime build up in there and a ridge develope's. Also seen it happen with boosted water/ methanol set ups when the inside of t-body gets corroded and dries out and friction going on develope's a ridge inside there.
I also just tried to do a base idle reset and I unplugged the spout connector and the iac and the tps and set the idle screw where it was barely running but running smoothly and first I plugged in the spout connector it idled up a little bit then I plugged in the iac again idled up a little bit but still ran smooth then I plugged in the tps and it ran like poop started surging and running like poop
 

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When i first bought my car it would randomly hang idle and start idling at 1200rpm. After a lot of diagnosis and troubleshooting i finally tracked it down. I had a bad positive cable from the battery to the fuse box. I found it by doing a voltage drop test. I would suggest you turn on every electric accessory your car has such as heater, defroster headlights on high beam ect. While running do a voltage drop test between the battery terminal and each point of connection. And do the same between the block ground and chassis, chassis and battery terminal and block and battery terminal. This could easily be a voltage drop issue.

This video explains how to test the starter circuit you can check the remaining circuits by turning everything in and simply checking from point to point

 
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I kind of had some issues like your experiencing with my 89. I tried a different newer tps and it totally went berserk thinking I'd upgrade it with a newer one. Then comparing that tps to another good one I had the color of wires coming into back of the sensor were in different order. From driver side to passenger side my good one on the car now wires are in order from orange green black. The car didn't like the tps sensor with wire order black green orange.
Electrical wiring Audio equipment Gas Cable Coil
 

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Let this be a lesson. Don't ever get rid of old parts thinking you don't need them because they were replaced with new. But anyway. Do that voltage drop test Dwain posted. Try another TPS. Get one from a parts yard off another vehicle.
 

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Discussion Starter · #80 ·
Let this be a lesson. Don't ever get rid of old parts thinking you don't need them because they were replaced with new. But anyway. Do that voltage drop test Dwain posted. Try another TPS. Get one from a parts yard off another vehicle.
Okay so I got the surging problem fixed and the car doesn’t die on my anymore now the idle is high and the throttle sticks a little bit and I have to kick it hard to get it to start moving
 
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