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random high idle

my 87 5.0 bird has a random high idle issue, there are no codes, I've cleaned the IAC then swapped it for another one I had on had. She doesn't do it all the and there seems to be no rhyme or reason as a matter of fact it wont do it for a couple of days then all of a sudden it will start up again, other than that she runs fine its just annoying sitting at a light and all of a sudden the idle jumps up...any thoughts

random high idle

Reply #1 –
What is the idle speed fluctuation?? And did you do a MIN IDLE SETTING. What is your TPS voltage?? Should be around .50-.60 Volts  MAX. Never exceed .60 Volts on a TPS ADJUSTMENT shoot for .55 Volts and do you have a IAC restrict-or i posted many times before for this issue. Also did you do my IAC mods and completely disassemble it and polish the seat and valve. those IAC valves are finicky. If when removed you can blow air through it it is NG. Use my mods and your idle issues will be over. That is of course unless you have a big cam and that is another story. Or other issues like a vacuum leak ETC. have a great day guys
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

random high idle

Reply #2 –
The tps voltage doesn't. Matter as long as its between .6 and 1.27 volts. The computer knows no difference.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

random high idle

Reply #3 –
Give your salt and pepper shakers (injection harness to main EEC harness connectors behind the intake) a look.  I had all kinds of random issues with mine only to find out that the connections had become expanded over time and I was getting intermittent contact which resulted in weird codes and mystery issues with no codes.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

random high idle

Reply #4 –
Quote from: Aerocoupe;438046
Give your salt and pepper shakers (injection harness to main EEC harness connectors behind the intake) a look.  I had all kinds of random issues with mine only to find out that the connections had become expanded over time and I was getting intermittent contact which resulted in weird codes and mystery issues with no codes.

Darren

that was going to be my recomendation.  Ill see if I can find a link.
Mike

random high idle

Reply #5 –
My 88 used to do this occasionally took. Sometimes, if my foot wasnt on the brake hard enough the car would lunch forward. I wen through and cleaned everything like you mentioned, cleaned every contact on the salt and pepper shakers like other have mentioned, and never definitively found the problem. I had a code in my computer, something like a pin 30 disconnected or something, and it was the last thing I ws going to try. Have you run codes and come back with 'All Clear'?

I ended up trading the car in fora Genesis Coupe in March of 2011. (Worst mistake ever).