North American Turbocoupe Organization



Need help on my idle problem
evintho Offline
Senior Member
#1
'86 TC w/190K. Overall the car is in excellent condition and runs like a top. For the last couple of weeks when I come to a stop and push in the clutch, idle drops to 300-400 then dies. Doesn't do that every time just every now and then. Lately I'm noticing when I come to a stop it either idles at a good 1000, drops to 300-400 and dies or idles at 1500!

So I pop the hood while it's idleing at a good 1000 and pull the IAC connector. It immediately dies. I BrakeKleened the IAC solenoid about 40K ago. Do I just have a worn out IAC or could it be something else?
Any help is greatly appreciated!
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
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RDOG Offline
Posting Freak
#2
IAC, TPS out of range, or intercooler piping/hose leak.

I'm going with a dirty IAC.
1986 Turbo Coupe. Boport StageIII head, Boport 2.1, Performance Techniques 50 trim hybird, StageII.63, stinger 3" exhaust, Phenolic spacer, Boglog header,NPR FMIC intercooler setup, kirban fpr, bigrmotorsports fuel rail, diablo water meth kit, CAI, remote mount TFI, CHE rear adj control arms, MAC girdle, 8.8 rear disc, aluminum drive shaft, H&R lowerings springs Tbird Turbo Specific, y MAS!!
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Paulie Offline
Banned
#3
Sir sounds like you need to do a MIN idle adjustment. This can be accomplished as follows. With a worm engine disconnect the IAC harness and start the engine. If it does not idle crank the MIN idle screw in untill it idles at 750-800 Rpm. Once this is finished adjust the TPS to .95-.98 volts. Then hook up the iac connector and take the car for a ride to let it settle in. You may have to do this a second time to get it correct. Good Luck

Note make sure the IAC is clean and is working properly
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evintho Offline
Senior Member
#4
Pulled the IAC today. It's clean and the rod moves freely. I just ordered a new IAC from RockAuto. Probably should have checked the TPS first although it was in range 40K ago.
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
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Stinger Offline
Senior Member
#5
It shouldn't die when the IAC is unplugged. If it does, you either need to reset base idle or figure out what changed since the last time you set base idle.
www.Stinger-Performance.com

85 TC
85 SVO
86 SVO
87 Merkur
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evintho Offline
Senior Member
#6
With the IAC unplugged, I can't get it to idle at 800-900. It'll idle about 1350 but will die below that. When I plug in the IAC it jumps to 1500 so I just adjust the idle to 1000 with the IAC in. Help!
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
Reply

Stinger Offline
Senior Member
#7
Vacuum leak?
www.Stinger-Performance.com

85 TC
85 SVO
86 SVO
87 Merkur
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evintho Offline
Senior Member
#8
That's one of the first things I checked. Most of the lines are new. Even replaced the gasket on the oil fill cap. Weird thing is, with the IAC unplugged it won't idle below 1300 or so.
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
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Paulie Offline
Banned
#9
Quote:Originally posted by Stinger:
Vacuum leak?
^^^^^^^^Sir Check all external hoses and even the intake gasket. They can sometimes let go on cyl 1&4. Sounds like a VACUUN LEAK FOR SURE Good luck
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Paulie Offline
Banned
#10
Sir try this!!! Make a blank plate to replace the IAC gasket. Install it between the iac and the mounting on the upper. Start the engine and if it idles you have a vacuum leak for sure. If not then something is messed up with the IAC sensor. Remember the 2.3 IAC is a bypass sensor. It bypasses air even wnen the valve is closed. Thank you
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