The car and problem:
86GT 4-speed. 100K. Replaced Plugs & Plug wires, EGR tube, O2 sensor, EGR valve. Car will sit and run/idle at 950RPM for as long as you want. Timing OK. Increase the RPM's to 1800-2400 and both exhaust manifolds will turn cherry Red within 30 seconds. No codes, changed ECM to verify ECM OK.
Have checked vacuum, seems OK,(idle is constant at 950-1000), also, if you cover the throttle body, engine dies immediately. Replaced exhaust/catalytic converter.Need some "tech" help/suggestions on this one!

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Paul Vargyas
Northern Illinois Fiero Enthusiasts
88 Formula V8. More pics @ " TARGET=_blank rel="nofollow">www.xnet.com/~paulv

Paul, thats pretty much normal. With the car at higher RPM from idle, while at a standstill, there is no airflow over the manifolds to help cool them down.

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1988GT T-Tops, 5spd, Loaded

Paul, only time I ever had the manifolds turn red like that was when I had done some work requiring the dist. be pulled when I put it back in I thought I had the timing close but was way off turned cherry red in a matter of seconds. Probably doesn't help you much but its the only experience I can relate.

Clogged injectors or weak fuel pump. At idle it's fine at 2000rpm it's running too lean. You can verify by hooking up a scan tool and seeing the readings. Your O2 will probably show very lean.

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Happiness isn't around the corner...
Happiness IS the corner.

I'm inclined to agree with both problems. either too rich or the timing is retarded waaay too much.

Got a dialback timing light? And if so how did you check timing? It does sound like you've got timing very retarded. May be that it's EST connector is unplugged? But you said no codes... Follow the emissions sticker if it's stock to check timing and if you've got a dialback timing light , make sure it's actually advancing. A rich mixture would actually make the exhaust temp cooler, not hotter, look for a lean mixture. Know anyone with a gas analyser? I could pop a probe in it and tell you what's going on in a couple of minutes if it was here.

You can take this for what it's worth, but I've owned approx. 25 to 30 new and used GT's and ALL of them got slightly red on startup at a similar RPM.

I find it hard to believe that the timing was off on all of them or that all of them were running lean. As far as I'm concerned. IT'S THE NATURE OF THE BEAST.....PERIOD.

Obviously others have different ideas, I only express my experiences. Thanks.

Phil

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GTDude
OVER 25 years GM experience

[This message has been edited by GTDude (edited 10-19-2002).]

[QUOTE]Originally posted by GTDude:
[B]You can take this for what it's worth, but I've owned approx. 25 to 30 new and used GT's and ALL of them got slightly red on startup at a similar RPM.

I replied as I did because he didn't say slightly red, he said cherry as in glowing? A Raytec remote thermometer would be a good idea maybe in this case since we can't see the car to see how hot they really are.

If he knows a mechanic or someone that owns one he could give us temperatures of the runners, then we could tell what we are really talking about. He's running a thinwall tubular header or cast iron exhaust manifolds?

I guess it all depends on whether you view the manifolds at night or in the daytime whether they look cherry red or just glowing, you don't say. Glowing in the day can look cherry red at night.

Phil

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GTDude
OVER 25 years GM experience

More info based on above:

OE stock manifolds.
They are "bright" red in daytime conditions, I also have owned numerous V6's, but I have never seen these get this bright Red, and so fast.

Thanks.....that clears it up.....they should not get that hot for sure. Agreed...timing or fuel problem.

Phil

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GTDude
OVER 25 years GM experience

Swap the engine for a 2.5L to eliminate "glowing manifolds".

HOLY SMOKE(excuse that!) Yeah just that. I meant to say too lean. Sorry if I did mislead anyone...