High Idle Problem after Complete Intake Upgrade

Dave Ward

Registered User
Just got done installing MP 85mm TB, Inlet Plenum, SC Top, MP Blower, 42lb Injectors, Double I/C and a 76mm C&L with the correct tube. Car runs fantastic but idles at 2K. When I disconnect the IAC valve, it drops to around 700. Also, with the IAC disconnected, the car will start. Could the IAC be stuck open? I was also thinking vacuum leak, but vacuum is at 19-20 and boost is at 16psi in third gear (Autometer Gauge)

Thanks in advance for any suggestions,

Dave
 
That's where I'd look. I cleaned mine out with some brake cleaner but unfortunately I stuck the straw to spray it a little to far in and cracked the diaphram and had to buy a new one anyway. I'd try cleaning it first, just don't be as careless as I was, it's pretty brittle because I didn't hit it that hard.
 
i added bigger throttle and mine acted up fast idle i tried unplugging iac then stalled on cold start otherwise ran good so i plugged it back in till i unhooked battery i couldnt believe it had me puzzled for 2 weeks now its fine
 
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U need to reset the puter after U mess with anything in the intake system. Warm up the engine then shut it down. Then disconnect the battery leave it off for a 10 minutes. Reconnect the battery turn off EVERYTHING! Restart DO NOT touch the throttle at all if it stalls re start until it runs. let it run 10 to 15 minutes. Re start 5 times letting it run for 5 min each time. This will do it. Now run it hard for a while so the puter will reset everything in the go fast mode.
 
Thanks...

Thanks for the help guys! I ordered a new IAC valve from Ford yesterday. The one that's on the car is a KEM unit that I put on about 4 years ago. It's reversed of the original, and from the research I've been doing, I'm surprised it worked at all. I've had the battery disconnected a few times since the install, but never longer than a minute or two. I'll probably give that a try tonight.

Thanks again for the advice!

Dave
 
If you have a sampling tube in the MAF to correct for the injector size, it could be part of the problem. In the EEC, there's a setting for 'Expected Idle Airflow' or something like that at idle and in drive. If it's off too much, it'll bump the idle up or down. An EEC tuner or chip are the only ways to fix it.
 
Steve, that thought did cross my mind. I was planning to get a tuner and have Fred make a file, but since I have a set of heads and a cam being done, I was holding off until then. Of course the heads won't be finished until AFTER Carlisle :eek:( All things considered, I'll probably be getting the tuner asap.

Thanks for the input,

Dave
 
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