I know, I've already done a search

Anyway, its an 85 GT Auto, and after fixing some crappy fuel lines and the fuel filter, both exhaust manifolds are glowing orangy-red, (in the dark). I know the trunk side manifold needs a gasket, but that doesn't explain the firewall side manifold glowing. I don't think there is a vacuum leak, as the idle is quite nice, and I think the timing is accurate (hasn't been checked though). And there is no cat.

What could it be?

you are running lean. This is the cause of the famous Fiero fires. Has the car sat for awhile? If so, check out your fuel pressure regulator.

Seperate your fuel lines on the right side by the battery, drop an electric pump into a bucket of Berrymans Injector Cleaner, let it cycle for a couple of hours.

Also, drop a note to GTDude.. he's forgotten more about fixing Fiero's than most of us know!

Have you ported the manifolds? My 85GT and 87GT would nearly always glow at night. After I ported them they haven't ever glown again.

I have a different opinion on glowing red manifolds.

It's Normal.

I've had 4 GTs, 2-86 1-87 and 1-88. They all glowed red in the dark after you first start it when the engine normally runs rich until it's warmed up.

Then they glow just at bit during low hot idle. But if you rev the hot engine, like a steady 2000rpms, watch them glow.

Just make sure you have a good oxygen sensor and and leak-free egr tube between the egr valve and red intake....no cracks in it. You'll be fine.

I've ported the manifolds on 3 of the 4 GTs. They glow a bit less, but it's no cure.

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Ron Dittmer - 88GT Automatic with 30,000 miles and climbing
Former PFF name Ron_Dundee

You know, I'm in the middle but generally agree. If you can see them glow in the day time something is wrong. At night, you can see some hot area's if you've really been on it. That's normal. They aren't cast iron.

A lean/high EGT glow is cherry red and blinds you in the middle of the day with neutron rated Ray-Bans on.

Yes, the car has sat for a while, but as far as I know, it was ran occasionally. The o2 sensor looks quite old.

If it could use it, give the car a tune-up, make sure the timing is set correct, and that the CAT isn't plugged. Most all Fiero manifolds will have a slight glow at night in spots. Its normal.

quote Originally posted by fiero56: and that the CAT isn't plugged.

It has no cat

I'm kinda thinking that it is normal, it has new plugs & wires, gonna change the oil and dist cap and pickup.

also way retarded timing will make 'em glow
if you set the timing without shorting the ACL
pins, you will end up with retarded timing &
glowing manifolds

I emailed blazin to find out what it turned out to be because I'm researching a similar problem. Here is his reply:

I have to agree with Phil (GTDude) that is normal for them to glow just a bit, at night that is. When I originally made the post on the forum, the car was running quite rich, and thus making the manifolds glow bright red. What I did change that seemed to improve the problem was change the coolant temperature sensor, which tells the ecm the temp. of the engine and regulates the fuel mixture based on its readings. After that, the manifolds only glowed around the exhaust ports. But there are a few things that can cause this, I guess I got lucky with it being just that sensor.

LMK!

Later!

hot