North American Turbocoupe Organization



Idle Question
Dan E Offline
Posting Freak
#1
The engine still runs well, however I have question...

The base idle was set with IAC unplugged to roughly 800rpm (would die below that). With IAC plugged back in, it idles at around 1,100 rpm. Base timing was set with spout out to 10deg.

Runs midly rough at 1,100 but smoothes out at 2K on up. I have rev'd to 5K and runs really smooth from 2K to 5Krpm. After a rev up to 3K or more, when decellerating it dips to below 1Krpm and wants to try and sputter but catches itself and idles back to 1,100.

Also, I noticed that when headlights are turned on it drops the idle speed for a moment then goes back up (same thing if brakes are applied).

Also, how much of an adjustment should I make in the Adj Cam Sprocket ?

Any ideas ?

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88TC 5spd, Shortblock with Crower 5.5" Sportsman Rods and 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 Turbo, 3" DP w/No Cat, RR Cam, Adjustable Cam Sprocket, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pullies, and the DAMN Heater Core is new too !
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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1987tc Offline
Senior Member
#2
Dan,
except for the roughness that is the way my 87 has always been. Smaething with the idle changing a little when I step on the brakes or turn the headlights on. Not a big change but you can still detect it easily. There is a pretty good load from the headlights and from the brake pump. This puts more load on the alternator and it takes a second to catch back up.
When we check peoples charging systems at work we make sure to have everything in the car turned off for the same reason. As the machine puts a load on the charging system you can hear the engine change sound and speed. Some cars a lot.
Wes

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1987 TC:
Hurst compition plus shifter,K&N cone,rollor cam,custom single exhaust,Gillis valve,H&R springs,KYB shocks,struts and quads.
3.73 rear. lots more to come!
Linton Indiana
Sold my Turbocoupe. It went to a good home.
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Chris Ruhl Offline
Member
#3
To adjust idle properly I would use the info. told when the web page comes up. That is you take and adjust the throttle positioning sensor using a voltage meter and a screw driver. Check into it. It's useful information.
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Jeff K Offline
Administrator
#4
Dan...Check the TPS voltage as you open the throttle to be sure it increases smoothly from ~1V to ~4.7 V

Also check the VAF output voltage as you manually push the flapper door open to be sure voltage increases smoothly.

Did you run the KOEO test to be sure all the sensors are hooked up and within normal operating range? (maybe do this first [Image: smile.gif] )

Did you put the SPOUT plug back in? I have lost track of how many times I forgot to put it back in..... forgot again for the millionth time a wek ago when I was working on my 5.0.

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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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Dan E Offline
Posting Freak
#5
I thought that the headlights and brake pump weren't a big concern.

I had planned to set the TPS this afternoon...and forgot to mention that.

Ran the codes...everything checked out OK except the KS test code 25 (I didn't hit the Intake), the EGR code 34 (which always comes up)...

Yep, spout was connected...

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88TC 5spd, Shortblock with Crower 5.5" Sportsman Rods and 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 Turbo, 3" DP w/No Cat, RR Cam, Adjustable Cam Sprocket, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pullies, and the DAMN Heater Core is new too !
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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DrPhang Offline
Senior Member
#6
My TC does the same stuff to

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Ummmm!
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JT Offline
Posting Freak
#7
It sounds to me that your "problem" with the idle when you turn on the headlights or the brakes are normal.

As one mentioned, the headlights take a load on the alternator, which drags the RPM of the engine down.

The EEC suppose to monitor (among several other things) volts and suppose to "bump up" the idle to increase the RPM of the alternator to help handle the load when it detects a drain in the charging system.

Much like it does when the A/C system is on. It detects the A/C clutch operation, and tries to bump up the idle to help minimize a big RPM drop due to the load.

JT

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JT
[email protected]
www.geocities.com/turbocpe/
1987 T-Bird Turbo Coupe T-5
1994 T-Bird LX 4.6L
1988 T-Bird Turbo Coupe A4LD
1988 T-Bird 3.8L
1979 T-Bird Heritage 351M
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Pete D Offline
Administrator
#8
After checking the TPS and setting it correct, put a vacuum gauge or do the carb cleaner check for a vac leak, just to make sure.

Cam adjustments should be done in 2* increments, but resolve the idle problem first.
Pete Dunham


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Matuszak88tc Offline
Member
#9
Gentleman, I had the same the problem as you did. all I did was change my timing belt and it got rid of the odel fluctuation. good luck
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Dan E Offline
Posting Freak
#10
Today I set the TPS to .97 Volts. I also got the hood on. So, I took it around the block.

I must say I was disappointed with the test drive. Everytime I depressed the clutch to come to a stop it sputtered and DIED. It still runs rough at idle.

I am quite sure that this is a timing issue.

What I am unsure of is the adjustable cam sprocket. The center section was loose when it arrived (go figure RW...). The only way I had to orient it was to align the keyway with my fixed Cam Sprocket and to mark a tooth on the adj cam sprocket that matched the arrow on my other sprocket.

So how do I know where to have the center section aligned ???????

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88TC 5spd, Shortblock with Crower 5.5" Sportsman Rods and 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 Turbo, 3" DP w/No Cat, RR Cam, Adjustable Cam Sprocket, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pullies, and the DAMN Heater Core is new too !
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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