Misfire

[Ragtop_Renegade]

Now this is strange. 86' 4cyl 5 speed. The idle is a little rough but for the most part ok. Under power and mostly in higher gears the engine bogs down and sometimes will come back suddenly , usually when it hits 3000rpm or better. It really feels like a misfire. The plugs,wires,cap and rotor are all new and are ACDelco OEM parts, not the cheap kind.

One night I lifted the decklid in the dark after driving for 15-20 minutes and the exhaust manifold was GLOWING ORANGE. I thought this was a plugged up converter and the cause of the sluggishness but when I hacked off the old converter it was completly clear!!!!

Could this be a bad coil , or maybe a distributor pickup? Why does the manifold glow like that? Is it fuel from misfiring cylinders combusting in the manifold?

Even with 2 years of school and an automotive degree I am just plain confused here. I have seen one other car (a Celebrity) that had a glowing exhaust manifold and the converter was fine. That car was scrapped because we never did figure out why it did that.

[RedFiero]

Originally Posted by Ragtop_Renegade

Now this is strange. 86' 4cyl 5 speed. The idle is a little rough but for the most part ok. Under power and mostly in higher gears the engine bogs down and sometimes will come back suddenly , usually when it hits 3000rpm or better. It really feels like a misfire. The plugs,wires,cap and rotor are all new and are ACDelco OEM parts, not the cheap kind.

One night I lifted the decklid in the dark after driving for 15-20 minutes and the exhaust manifold was GLOWING ORANGE. I thought this was a plugged up converter and the cause of the sluggishness but when I hacked off the old converter it was completly clear!!!!

Could this be a bad coil , or maybe a distributor pickup? Why does the manifold glow like that? Is it fuel from misfiring cylinders combusting in the manifold?

Even with 2 years of school and an automotive degree I am just plain confused here. I have seen one other car (a Celebrity) that had a glowing exhaust manifold and the converter was fine. That car was scrapped because we never did figure out why it did that.

Have you tried to adjust the heat range of the plugs? Maybe a cooler plug would work. I had a 65Malibu w/a 327/365 Vette Mtr. and the headers use to glow at night too, but it always did run extra hot.

[Ragtop_Renegade]

On a newer stock, fuel injected, emmisions controlled engine there shouldn't be a reason to change the heat range of the plugs... Someone did mention my distributor might be 180 degrees out of time so I'll try re-timing the engine. When I pulled the distributor I noticed a lot of rust built up on the distributor pickup, that might be why it misfires alot and so randomly.

[RedFiero]

Originally Posted by Ragtop_Renegade

On a newer stock, fuel injected, emmisions controlled engine there shouldn't be a reason to change the heat range of the plugs... Someone did mention my distributor might be 180 degrees out of time so I'll try re-timing the engine. When I pulled the distributor I noticed a lot of rust built up on the distributor pickup, that might be why it misfires alot and so randomly.

Ya when I bought my Fiero it wouldn't run because of the rust on the PU's. Mine was so bad that I had to replace the entire Dist. 180 degrees out of time I doubt that the car would run let alone overheat the manifold. Try the dist cleaning 1st. Good Luck R.

[Ragtop_Renegade]

Well, the engine is retimed and the distributor cleaned up, the car does run much better but I still get that freaky orange glow off the exhaust manifold.... Don't know what could be causing it. Going to try swapping the coil as I have a spare. Could carbon buidup in the manifold make it do that? If carbon was that bad in the exhaust, I would think it would be just as bad in the head and the engine would diesel, but no. Anyone with any small idea please chime in

[fieronut]

hay... same problem i posted a new thread on that. i did an intake and perfectly in time i could bake a cake on the deck lid...sooooooo puzzled. glowing manifold WTF???

[fieronut]

i can only think it is a timing problem. car was fine when i drove it into my shop

[lakerfan1784]

you most likely have a lean-burn condition, that causes the manifold to glow red. my friend's 87 did the same thing, although I cant remember what he did to fix it.