North American Turbocoupe Organization



Tune up question - Help please!
Noname
Unregistered
#1
Hey guys,

I just replaced the plugs on my '88 TC. The original ones were pretty clean, but definitely needed replacing. New plugs are in, and I was going to check/set the timing. The idle speed was too high, maybe 1050 to 1150, but smooth. Then all of a sudden the idle speed jumps to about 1800 and it won't come down. I looked for any vacuum leaks and I don't see any, but I guess there could be one.

Oh yeah, the clamp on the turbo-to-intercooler was gone, and the intercooler was just sitting on top of the turbo - not much boost (or vacuum, I'm sure) there. I replaced it and the car was running a lot smoother when I first cranked it back up. Now if I could just get the idle and the timing set!!!!!!

Any and all help will be appreciated!!!
Reply

Dan E Offline
Posting Freak
#2
Coach,

Our TC's are known for idle surges like you mentioned. A variety of things contribute to the situation.

1) The Throttle Position Sensor (TPS) should be set to around .98 Volts (see the article in the technical section).

2) The Idle Air Control Solinoid (IAC) can get gunked-up. It is the cylindrical looking thing on the back of the Throttle Body. Take it off and blast the crap out of it with Carb Cleaner.

To set the Idle Speed:
1)Warm up the engine
2)Unplug the IAC
3)Adjust the Idle Screw until it runs at about 750rpm (almost ready to die).
4)Plug the IAC back in

Let us know...

------------------
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...
Reply

Noname
Unregistered
#3
Thanks Dan,

I'm out to try it. I'll let you know what happens.

Chuck
Reply

Noname
Unregistered
#4
Dan,

Should the engine die when I unplug the IAC? The guy I bought it from said he had replace it, but after I got it off, I think the only thing he replaced was the solenoid on the end - the actual valve was gunked up with carbon. I blasted it all out with carb cleaner.

Thanks,
Chuck
Reply

Pete D Offline
Administrator
#5
Coach, it's tough to get the idle down to 700-750 before plugging the IBC (IAC) back in. take it down to the lowest point you can without killing it. Although not in the procedure, if mine idle a little high when I plug the IBC back in I just turn the adjusting screw out a little. Make sure your linkage isn't binding

------------------
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS.
Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges. New engine shortly, ported head and
manifolds, polished and cc'd chambers, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, Walbro 190 pump and T-3 for starters. KB subs
and jack rails.
Pete Dunham


Reply

Dan E Offline
Posting Freak
#6
Quote:Originally posted by SoccerCoach61:
Dan, Should the engine die when I unplug the IAC?

Like Pete said, it's hard to get it to this point before it dies. I have my hand on the linkage when I unplug it and I'm ready to give it a little "nudge" to keep it from dying...then ease back off of the throttle until it settles down to as low as it will idle. Then plug the IAC back in. I also do what Pete said and adjust the screw a tad (if necessary) after I plug the IAC back in.

If it does die, plug the IAC back in before you try and start it...
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
Reply

Dan E Offline
Posting Freak
#7
Quote:Originally posted by Pete D:
...before plugging the IBC (IAC) back in...Make sure your linkage isn't binding.

Pete, your getting this confused with your Mylanta Again....remember that's "I BM"... [Image: biggrin.gif]

Just so as to not confuse you Coach... "IAC" for Idle Air Control or "IBC" for Idle Bypass Control or "IABC" for Idle Air Bypass Control or "IBM" for International Business Machines or "ABC" for Alcoholic Beverage Comission (liquor stores in the South...which is where most end up after working on TC's)...confused...OK U2 LOL ???



------------------
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...
Reply

Noname
Unregistered
#8
Update:

I got the Throttle Position Sensor adjusted to .94 volts, the voltage change is smooth as you open the throttle. I blasted out the IAC valve with carb cleaner.

When I put it all together, and the car was warming up, there was a little lopey idle, but not much; but the minute the thing warmed up, the idle shot back up to about 1750 and won't come back down..

Could the IAC valve be bad?

Thanks again for all your help!!
Chuck
Reply

Noname
Unregistered
#9
Quote:Originally posted by Dan E:
Pete, your getting this confused with your Mylanta Again....remember that's "I BM"... [Image: biggrin.gif]

Just so as to not confuse you Coach... "IAC" for Idle Air Control or "IBC" for Idle Bypass Control or "IABC" for Idle Air Bypass Control or "IBM" for International Business Machines or "ABC" for Alcoholic Beverage Comission (liquor stores in the South...which is where most end up after working on TC's)...confused...OK U2 LOL ???


[Image: biggrin.gif] How about this one: IAH2TC, which stand for "I am headed to the casinos" which is exactly what I'm going to do in a little while.. A little black-jack to ease the nerves, and hopefully I'll win enough to restore the car! [Image: biggrin.gif]
Reply

Dan E Offline
Posting Freak
#10
It is not unheard of for there to be a short in one of the wires to the IAC. The "jiggle test" of the harness may let you know.

But, before going on too many wild goose chases (and I should have said this before), have you run the Diagnostic Codes yet ?
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
Reply





Users browsing this thread:
1 Guest(s)



Theme © iAndrew 2018 - Software MyBB