North American Turbocoupe Organization



Idle problems
TC88 from Finland Offline
Member
#1
Hello all turbo-Ford owners!
Greetings from freezing Finland (North Europe)! I´ve been an owner of 88 TC for one and half years now and I can tell you that TC is quite a rare car around here. My TC is very original and mileage is only 87 000. I have liked my car very much, it's great driver and surprisigly fast. Originally it was equipped with automatic but A4LD didn't like my driving style and blew on last spring. I was lucky and was able to locate T-5 and other parts from here (from 90 4-cyl Mustang) and so now my TC is equipped with 5-speed.

But there is a very irritating problem, rough and irratic idle. I have set the basic ignition timing to 10 degrees and base idle to around 800 rpm without IAB. When I reconnect the IAB, idle sets up to around 1000 rpm, so feels that everything is ok. But very often idle rpm rises to around 2000 rpm and stay there, sometimes when driving sometimes when idling. There is no logic at all. Usually this problem occurs when engine has warmed up but sometimes it does this also when engine is cold.

Spark plugs are almost new Boschs, spark plug wires are new Ford Racing 9mm ones, rotor and cap are ok, IAB and EGR are cleaned and TPS adjusted. EEC Self diagnosis doesn't give any trouble codes exept when car has idled few minutes with high rpms. Then CE light appears and code 42 (rich mixture) appears to continuous memory. CE light disappears when throttle is depressed and car accelerated.

When engine is idling high, disconnecting the IAB gets rpms to drop to normal 800. Could there be a problem with that IAB even though it's cleaned and works usually fine. Or could this problem be caused by some broken sensor ,ACT maybe (I have changed the temperature sensor already).

There is also a problem to get the car started when it's very cold (around 0 F), feels that cold start enrichment system doesn't work very well. Engine doesn't get rich enogh mixture to start (just like trying to get old carburator engine started without choke). When engine has started it runs quite smooth and ok, rpms around 1500 for a while. Could these problems be linked to each others somehow?

Thank you all for answers! I start to feel desperate because this problem has been around for months and feels that nothing helps!!



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Lauri Salokangas
Tampere, Finland

1988 T-bird TC 5-spd
Lauri Salokangas
Tampere, Finland

1988 TC 5-spd, black with raven int.
K&N, CAI, Gills, Walbro 255lph, Kirban AFPR, BOV, 3" Stinger exhaust. Rebuilt diff and trans, 3G alt, Energy Suspension bushings, KYBs

1984 Mustang SVO
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Dan E Offline
Posting Freak
#2
When you checked the TPS what were the readings ? It should be around .96 to .98V with throttle closed and a smooth voltage increase to around 4.5V at WOT.

The "roaming" idle is a very common problem with these engines.

I fought this problem for a long time. Turned out that my VAM was the problem !

Another thing that can affect this is the ECT sensor (between the #2 & #3 Injectors on the Lower Intake). This could also explain the cold start problem.

Do you have a code scanner / Have you run the codes ?

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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 !

http://www.geocities.com/wot_turbo/WOT.html

NATO MEMBER (Vice Chairman...if it's a vice...I deal with it)

[This message has been edited by Dan E (edited 02-05-2003).]
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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Turboy Offline
Member
#3
I also fought this problem for a while and did most of the same things you did.....turned out to be a bad TPS (even though I got "good" readings out of it). $28 later problem was solved!

Good Luck!

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1988 TC 5 spd K & N, Bleeder. Next up - 3" downpipe to 2.5" duals
1988 TC 5 spd K & N, Bleeder. Next up - 3" downpipe to 2.5" duals
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Pete D Offline
Administrator
#4
Lauri, welcome to the board. i'll bet it's cold where you are.

It seems like you have done many of the things we would recommend for starters. These things are notorious for idle problems and anomalies. I would suggest a couple things:
Erase the continous codes and do the TPS test that Dan suggested. This allows you to check the base setting and then look for sign of wear throughout the range of motion of the TPS.. There is an article on setting idle and TPS in the Technical Articles section. If the TPS checks out OK then leave it in, for now. Then drive it a few times and see if anything changes. This will give you a chance to see if the code 42 comes back to determine if it represents a current problem. If at this point it stills idles irratically, replace the TPS, even though it looked OK for the above test. I don't like to advise people to buy parts until the defect can be pinpointed but this is one of those situations where the defect doesn't always show up.

My last suggestion would be to get rid of the Bosch plugs. We have heard to many cases of them being part of a problem. Autolite 764 coppers work very well as do the Motorcraft equivilant. gap to 0.032-0.033. Please let us know how it turns out


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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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Jeff K Offline
Administrator
#5
Welcome to the board!

As others have said, check the TPS voltage at closed throttle (between green abd black wires, key on, engine off). Voltages over 1.0V are a common cause of hanging high idle speeds.

Cold start: check the resistance of the ECT when cold. At 50 deg F, it should be about 58,000 ohms, and it should be higher at colder temps.

Have you removed the IAB and blasted it clean with brake cleaner? A dirty IAB could stick, causing both your high idle and cold start problems.

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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 // 00 Windstar (wifes vehicle)
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
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TC88 from Finland Offline
Member
#6
Thank you for tips!

I already have new ECT so it should be working. I also have adjusted TPS to 0,95 but maybe a new one should be purchased. How can I check that VAM is working properly (I have checked the vane - it's moving freely). Have you had problems with ACT, could it be the one which causes these idle problems?

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Lauri Salokangas
Tampere, Finland

1988 T-bird TC 5-spd
Lauri Salokangas
Tampere, Finland

1988 TC 5-spd, black with raven int.
K&N, CAI, Gills, Walbro 255lph, Kirban AFPR, BOV, 3" Stinger exhaust. Rebuilt diff and trans, 3G alt, Energy Suspension bushings, KYBs

1984 Mustang SVO
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bit Offline
Junior Member
#7
Hey Brid guys I joined for this post. I added a supercharger to my 5.0 about a month ago. Ever since then I have had the same problem. My search for answers has lead me here. I have tried all of the above and tomorrow I will be trying to tune it out with a custom chip, but I am still looking for any suggestions.
Thanks
Brent

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BlackStang.tk
49erStreet.tk

91 LX 5.0 Conv. 5-Speed Triple Black
K&N, and other mods

Have you CHASED a Ford lately?

Caution: Not For Little Boys Who Wear Bow-Ties

UNC Charlotte - 49er Motorsports

[This message has been edited by bit (edited 03-21-2003).]
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