wont start
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 17
Likes: 0
IIRC, you start the car by giving it slight throttle, let it run for ten seconds and then just turn it off while holding the throttle in place.
Don't order the TPS until you clean the IAC to determine that's the cause.
Please, unless you just want to throw parts at it. I doubt the TPS is your problem. That's why the car will run with you giving it throttle. For lack of a better way of saying it, the TPS already knows where the throttle is and bypasses the IAC, as it's no longer needed.
You need the IAC for idle only. Hope this makes sense.
Don't order the TPS until you clean the IAC to determine that's the cause.
Please, unless you just want to throw parts at it. I doubt the TPS is your problem. That's why the car will run with you giving it throttle. For lack of a better way of saying it, the TPS already knows where the throttle is and bypasses the IAC, as it's no longer needed.
You need the IAC for idle only. Hope this makes sense.
Instructor
Joined: Feb 2007
Posts: 160
Likes: 1
From: Auckland
Hey guys. Just out of curiosity, i've had a similar(ish) problem with my '86. Although, from cold start after holding my foot on the accelerator for about a minute, the car will 'take it' from me (revs climb by itself), and then it holds idle fine, and I drive off as normal.
Sound like an IAC problem for me?
When I first got stuck (car randomly died in traffic after driving out of a bumpy driveway) I wound up the stopper on the throttle to make it hold about 7-800 rpm at idle, otherwise it would just stall.
Kind of hard to explain, maybe one day i'll create a thread and make some videos of the problem. Any advice appreciated, cheers
Sound like an IAC problem for me?
When I first got stuck (car randomly died in traffic after driving out of a bumpy driveway) I wound up the stopper on the throttle to make it hold about 7-800 rpm at idle, otherwise it would just stall.
Kind of hard to explain, maybe one day i'll create a thread and make some videos of the problem. Any advice appreciated, cheers
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Would I be escorted out of the C4 Forum if I said the car is doing exactly what it can be expected to do in it's PRESENT condition? The CSI adds fuel during cold starts and maintains a rich condition until a given heat level is reached, which is kinda quick, think choke on a carb. By deleting the CSI the ECM has no actual way to enrichen ( is that a word?) the mixture though it thinks it has. The driver overcomes this by opening the throttle, fooling the TPS into thinking the engine needs more fuel for higher rpm/power level. ECM adds fuel, enrichens (there's that word again) and the car starts. In later years, with no CSI the ECM, sensing a cold start adds additional fuel through the injectors without opening the throttle. Certainly cleaning and adjusting the TPS and IAC are good but I question if that alone will solve the problem. When I wired a 165 ECM into my 85 I went through several years of chip programming. Ended up with the ARAP bin from an 89. No CSI programming but cold starts are instantaneous.
Team Owner
Joined: Jan 2009
Posts: 73,568
Likes: 33
From: Somewhere in Mo
St. Jude Donor '09-'10, '14
Hey guys. Just out of curiosity, i've had a similar(ish) problem with my '86. Although, from cold start after holding my foot on the accelerator for about a minute, the car will 'take it' from me (revs climb by itself), and then it holds idle fine, and I drive off as normal.
Sound like an IAC problem for me?
When I first got stuck (car randomly died in traffic after driving out of a bumpy driveway) I wound up the stopper on the throttle to make it hold about 7-800 rpm at idle, otherwise it would just stall.
Kind of hard to explain, maybe one day i'll create a thread and make some videos of the problem. Any advice appreciated, cheers
Sound like an IAC problem for me?
When I first got stuck (car randomly died in traffic after driving out of a bumpy driveway) I wound up the stopper on the throttle to make it hold about 7-800 rpm at idle, otherwise it would just stall.
Kind of hard to explain, maybe one day i'll create a thread and make some videos of the problem. Any advice appreciated, cheers
The IAC on these things are problematic at times. They will cause you to stall at stops and have difficulty starting without opening up the air supply.
The IAC provides the needed air supply to the car when the throttle is off. If the IAC isn't opening it won't provide air.
Always clean the IAC as a first maintenance item when this happens, because it's a free check and will let you know if that's the issue, in most cases.
When you clean it, it still may not totally solve the issue but you will know if it improves the idle. I read the entire internet on the IAC when I had the problem and I actually had two issues going on at the same time so it was a nightmare determining I had an IAC issue.
Take out the IAC and look at the hookups if you buy a new one. There are two different styles and the parts store gave me the wrong one at first. Well actually the boys in Mexico packaged it wrong.
Team Owner
Joined: Jan 2009
Posts: 73,568
Likes: 33
From: Somewhere in Mo
St. Jude Donor '09-'10, '14
Would I be escorted out of the C4 Forum if I said the car is doing exactly what it can be expected to do in it's PRESENT condition? The CSI adds fuel during cold starts and maintains a rich condition until a given heat level is reached, which is kinda quick, think choke on a carb. By deleting the CSI the ECM has no actual way to enrichen ( is that a word?) the mixture though it thinks it has. The driver overcomes this by opening the throttle, fooling the TPS into thinking the engine needs more fuel for higher rpm/power level. ECM adds fuel, enrichens (there's that word again) and the car starts. In later years, with no CSI the ECM, sensing a cold start adds additional fuel through the injectors without opening the throttle. Certainly cleaning and adjusting the TPS and IAC are good but I question if that alone will solve the problem. When I wired a 165 ECM into my 85 I went through several years of chip programming. Ended up with the ARAP bin from an 89. No CSI programming but cold starts are instantaneous.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
If his was simple idle issue I would agree but his is a "no start". IAC may be a part of the problem but with the throttle closed he is in a lean condition with the CSI inop and he tries to start. I wonder if he has an idle problem after the engine warms some, say to the point it goes into closed loop.
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Instructor
Joined: Feb 2007
Posts: 160
Likes: 1
From: Auckland
When mine first started going south it did the same thing. I could hold the throttle for a spell and it would eventually take off on it's own. From working itself loose I would guess.
The IAC on these things are problematic at times. They will cause you to stall at stops and have difficulty starting without opening up the air supply.
The IAC provides the needed air supply to the car when the throttle is off. If the IAC isn't opening it won't provide air.
Always clean the IAC as a first maintenance item when this happens, because it's a free check and will let you know if that's the issue, in most cases.
When you clean it, it still may not totally solve the issue but you will know if it improves the idle. I read the entire internet on the IAC when I had the problem and I actually had two issues going on at the same time so it was a nightmare determining I had an IAC issue.
Take out the IAC and look at the hookups if you buy a new one. There are two different styles and the parts store gave me the wrong one at first. Well actually the boys in Mexico packaged it wrong.
The IAC on these things are problematic at times. They will cause you to stall at stops and have difficulty starting without opening up the air supply.
The IAC provides the needed air supply to the car when the throttle is off. If the IAC isn't opening it won't provide air.
Always clean the IAC as a first maintenance item when this happens, because it's a free check and will let you know if that's the issue, in most cases.
When you clean it, it still may not totally solve the issue but you will know if it improves the idle. I read the entire internet on the IAC when I had the problem and I actually had two issues going on at the same time so it was a nightmare determining I had an IAC issue.
Take out the IAC and look at the hookups if you buy a new one. There are two different styles and the parts store gave me the wrong one at first. Well actually the boys in Mexico packaged it wrong.
Will look into cleaning it when i've got some time on my hands. Got a couple of other things I need to attend to first with other cars here.
Cruising
Joined: Feb 2012
Posts: 14
Likes: 0
From: Brooklyn
easy. sounds like you need new plugs. My truck did the same thing. ill let you in on a little trick i just pulled the spark plugs out looked at the plugs and found the one that was black (this means your running rich) and i sanded down the black stuff and poured some oil in the spark plug hole andd it that fixed that
Le Mans Master
Joined: Jan 2008
Posts: 7,030
Likes: 10
From: Edmonton, Alberta
easy. sounds like you need new plugs. My truck did the same thing. ill let you in on a little trick i just pulled the spark plugs out looked at the plugs and found the one that was black (this means your running rich) and i sanded down the black stuff and poured some oil in the spark plug hole andd it that fixed that
