North American Turbocoupe Organization

Idle Adjustment Question
Rodger Offline
On my 88 TC, the idle, for the most part, is fine. It stays, most of the time, at 1000 RPM. The only time it varies is when I load the engine at idle, when the clutch is engaged and disengaged, as one would do when parking in a tight spot. The idle will then climb to 1200 - 1500 RPM and will be slow returning back to normal. It may take 10 to 20 seconds before it's back to 1000 RPM. I plan to clean the IAC, followed by the idle adjustment procedure in the Tech Articles. Can I expect my "slow return to idle problem" to be cured after this?
Also, my son just picked up an 88 TC but it has an auto trans. It idles at 1000 RPM in Drive but in Nuetral and Park it idles at about 1400 RPM; which gives a pretty good jolt when putting it in gear. Again, if I go through the procedure mentioned above; can I expect a cure? Thanks in advance.

philS Offline
Senior Member
>>can I expect a cure [from the procedures above] ?

Try it out and see! It may work. Since the idle is largely controlled by the computer, several things could cause the high idle that you are experiencing. It could be the IAC, the TPS, the VAM, etc. The throttle plate might be sticking right before it closes, keeping the idle too high. Have you checked out the linkage at the throttle body? It's also possible that someone manually adjusted the throttle return stop to make the base idle higher.

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Jeff K Offline
I have the same exact problem every now and then. I park the TC next to my garage on a slab, and backing into the spot requires tight turns going very slow, and slipping the clutch to avoid hitting the house, garage, othercars in the driveway, etc. If I bog it more than a little, my idle goes up, and takes 30 seconds or so to drop down to 1000. I know my TPS, base idle are set right and my IAC is 100% clean and operating correctly. Maybe it is supposed to do this? Maybe the EEC thinks the idle has dropped due to some slipping the clutch / bogging, and tries to increase idle to compensate, and then takes 30 seconds to relearn the correct idle speed? Maybe it is an emission thing? who knows? Since the only time this happens to me is occasionally when paking the car, and I shut it off right away anyway, I just live with it the way it is. Another TC quirk....

Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 02 Taurus Vulcan(wifes car)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized

Dan E Offline
Posting Freak
Quote:Originally posted by Jeff K:
Another TC quirk....

This is a recording.....

I have said all along it's a EEC glitch. Mine does it as well. Sometimes even when slowing for a stop light.

Funny thing is that I have found though is that if you get into the boost hard before you push in the clutch it rev's down faster.

Also I can get it to rev down by pressing the up switch on my window when the window is already closed [Image: rolleyes.gif] . Somehow putting an additional electrical load in it makes it rev down...go figure ???

Dan Eaves
88TC 5spd, Crower 5.5" Sportsman Rods, Short Wiseco Pistons bored .030" Over, Ported Head with Polished Combustion Chambers, Gutted & Polished Upper, Ported & Polished Lower, Polished T/B, Ported E6, SVO T3 .63AR Turbo, Bosch Bypass Valve, 3" DP w/No Cat, 2 1/2" DynoMax single cat back w/DynoMax Super Turbo Muffler, RR Cam, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pulleys, Walbro 255LPH HP Pump, Kirban Adj FPR, and the DAMN Heater Core is new too !

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Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...

Rodger Offline
Well, I have much respect for the replies I've received; therefore I'm not going to be concerned about the "slow to return to idle" problem that I only have occasionally, on my 5-speed TC. I went throiugh the idle adjustment procedure on my son's auto trans TC. It appears to have corrected the "high idle in Park" problem, allowing it to nicely shift into Drive. The TPS voltage was set at 1.4 volts before I worked on it. Thanks for the help.

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