i have replaced almost all vacuum lines - hard and soft ones with brake tubing and hoses.
replaced ignition coils, crank pos sensor, cables, plugs, MAP and TPS

it does have an occasional high idle. when started it goes to 2500rpm mostly it then slowly drops down to around 1200, but not always.
sometimes it does go down to a nice idle at around 900rpm after about 5 sec after comming to a stop.

also the tach sometimes randomly drops to 0. stays for a few sec to minute or so and comes back up.

does have to be cranked a few sec. to start.
am going to try new fuel and air filters soon.

thanks for your help
hans

quote Originally posted by 86 gt fastback: i have replaced almost all vacuum lines - hard and soft ones with brake tubing and hoses. replaced ignition coils, crank pos sensor, cables, plugs, MAP and TPS it does have an occasional high idle. when started it goes to 2500rpm mostly it then slowly drops down to around 1200, but not always. sometimes it does go down to a nice idle at around 900rpm after about 5 sec after comming to a stop. also the tach sometimes randomly drops to 0. stays for a few sec to minute or so and comes back up. does have to be cranked a few sec. to start. am going to try new fuel and air filters soon. thanks for your help hans

sounds to me like a vacuum leak?

You might try the old propane torch trick.

Work over the vaccum areas with an unlite torch an see if you find a place that causes the engine to run/sound different if it sucks in the propane. (no smoking etc.)

This can sometimes lead you to a missed leak.

or try the safe way- mist with water and monitor ide speed. Good for large leaks poor for tiny ones. For tiny leaks make a smoke generator using a cheap cigar and a hand pump. With the engine off, pump the plenum/manifold full of smoke in a dimly lit garage. Shine a flourescent lamp all around the engine and watch for escapaing smoke.

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87GT 3.4 Turbo- 0-60 5.2 seconds -Best
Engine Controls, ECM goodies, Chip
re-programming & odd electronics stuff

What I like to do is use a spray can cap or other sized object, attatch to the throttle body and plumb a line to it from my air compressor at regulate it to 10-15 psi. Then air up the engine and listen for hissing and spray with water. Sounds like it might be a bad injector though.

Just to be clear.... What engine is it? (some ov the V6 conversions have DIS...)

If this is an L4.... you may have a bad gasket at the bottom of the TBI unit. See the torque strut article in my cave for info why that happens.

The L4 also has one or two extra vacuum ports... make sure those are securely capped. One is to the left of the TBI.

There are more notes in my cave on the L4 and vacuum leak problems in general.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurasic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

Sounds like your on the right track. I don't see that you have and trouble code?
I had that problem, refer to these threads:
87 Duke Problem
Glowing Exhaust on DIS
Loss of power on DIS Duke
Quest for perfect idle
I wound up finding a vacuum hose that I missed leaking and I removed the IAC and cleaned it to make ours run better - on top of a lot of the things you've done. The Ogres' cave was an excellent resource on DIS as well.

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John DuRette
Custom 85 SE/87 Coupe
"Kinda makes you nostalgic for a Members Only jacket"

[This message has been edited by USFiero (edited 08-03-2005).]

Should the manifolds glow at all? Just wondering because I noticed mine last night for the first time. I was re-charging the a/c and had the tach around 2K while I was doing this, when I went back to the (dark) engine bay I noticed that the manifolds were glowing. When I dropped the rpms back to idle speed, they were still glowing, but very faint. I only noticed them in the dark. When there's light on them, they look normal.
So, is this normal?

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FORMERLY KNOWN AS: sqoach (so, uh...yeah.........I'm not a noob) :p

I can't imagine glowing manifolds can be that healthy. Fuel hose was rotten on the 87 for me too.