I noticed my headers glowing about a month ago and this probably is the root of my problems I have been having for 3 years. Anyway, they don't all glow the same intensity. I increased my idle timing to get rid of some of it so now it only glows on the 5, 4 and 6 tubes. This is the 3rd set of injectors in the car and this set is new. Using LT1 Edit I leaned out those cylinders by 25% and the glowing decreased by about 60%. So it seems that fuel is igniting in the tubes. Anyone had this type of problem?

I just thought I could probably swap the injectors around to see if the problem follows the injectors. Any other ideas?

This is a 96 Corvette, BTW

 

What problem have you been having for 3 years? My other most important questions are What's compression on all cylinders? What's leakdown on all cylinders? Perhaps those cylinders have a problem sealing the exhaust valves and thus the questions.

Why did you replace the injectors so many times? How did you come to the conclusion that you needed 42#'ers? What's the injector pulse width when the headers are glowing? Now that you leaned it out, what's the current A/F ratio?

Sorry got more questions than answers.

 

There is plenty to say about this car but I don't want to flood you with info. Virtually everything has been replaced except the wiring harness. Even though I do everything myself I have taken it to a number a Corvette specialists and I either scare them away when I tell them everything I have done or I find I know more than them especially with tuning.

I was chasing down a random missfire for a long time. This year I discovered my plug wires where being burned up in less than a week. I have had plug wires getting fried (within a week) for years so I went with the Jacobs ceramic wires (good for 2000 degrees) to make the car drivable. Still the real problem is the headers getting to hot. It does glow beyond idle too. At least at light throttle.

I have done a lot of parts replacement because I and no one could find a clue until the discovery of the headers getting to hot. I have had LT4, LS6 and now new 42 lbs injectors. I believe the problem has existed with all those for years because the plug wires getting burned.

Also I have had 3 "pros" PCM programs in the car with no solution and I have personally done about 1000 programs in the car with LT1 Edit. I had one of the local pros check over my program too.

This problem existed with the 350ci LT4 motor. It all started about month or so after the LT headers and hotcam install. Now it is a 383 solid roller with ported intake and heads with 58mm TB. The 42 lbs are big but I was planning on a SC later. The engine is new and the heads have come off for an inspection after that. I have a WB meter in the car and it indicates A/F is normal. AutoTap shows that the PCM is making a very small adjustment to get the 14.7 desired A/F. I don't remember the pulse width.

 

I swapped injector 5 with 1 and the problem did not follow. It looks like the next thing is valve adjustment.

 

Ok so the question stands, what is happening during a compression test and also a leakdown test? I'm inclined to feel that it has something to do with valve closure. Your indication of the problem occurring sometime shortly after the hotcam install tends to support this feeling.

 

Now is it a totally different engine since it is a 383 with solid lifters. Still the valve idea is something to pursue. I will probably do the adjustment the weekend.

 

I did the valve adjustment and found no surprises. I also found a spreadsheet with the exhaust temperatures recorded using my temp gun and back with the 350 ci engine and it was showing #5 about 100 degrees hotter than the rest. Back then #4 and #6 was not as hot as they are now. I really don't see a point in doing a compression check to check for a bent valve. It idles pretty good considering.

To bad I have the most unique problem in the world that no one can figure out.

 

Use a leakdown test to see if the valves are not closing all the way. There are other reasons a valve would not close other than just being bent. Maybe no one can figure out your problem since you keep discounting suggestions.

What would make only some headers glow and not others. Ignition timing? Not likely to be off on only a few cylinders. Fuel? Moving injectors didn't change anything. And you said AFR was dead on. What's left. valve closure! Assuming all movement of the valves is equal. That is, all adjusted the same and each cylinders valve components are moving the same amount. The last choice is clear.

If and this is a big IF you did all that can be done to eliminate all other causes. The choice is clear. Do the compression and leakdown. Then call me an idiot if they both pass.

 

I will probably do the compression test and leak down. It is on the list but I have my doubts since I found that spreadsheet with the recorded temps before I rebuilt the engine showing the same problem. Even with this engine the valves have been replaced after the rebuild.

 

Engine Compression Test

1 - 245 psi
3 - 235 psi
5 - 250 psi
7 - 245 psi

2 - 250 psi
4 - 260 psi
6 - 240 psi
8 - 240 psi

I don't have the real equipment for the leak down test but what I did was pump up the compression tester and let it sit for a half an hour. I saw a 5 psi change on the 3 cylinders I tested. Two of which were the ones that were glowing at idle. I don't see a mechancal problem. Does anyone think there is a valve or ring problem now?

 

Depends on how you "pumped" up the cylinder. Was the input source of the air completely cut off with a valve of somesort? Just leaving it connected to the air supply means nothing? There is no engine that would hold cylinder pressure for a half an hour unless there was something done incorrectly with the pressure. Or MAYBE you're using Gapless rings.

Without actually comparing input pressure to cylinder pressure as in an actual leakdown tester, it really proves nothing. A good engine should be no more than 10% difference. HOWEVER, you don't even care about any of that. Your symptom would have been more rudimentary than that. if what I said was true about valve closure being the problem, you would have heard air rushing out the tail pipe.

So the question stands, did you hear air (any amount) coming from the tail pipe?

 

OK, I see what you mean about holding the pressure. Looks like I was just testing the leak down of the tester itself. I will have to see if I can the get leak down equipment. Not sure where I can get that.

 

I got the real leak down test equipment today.

LEAK DOWN TEST
According to the gauge
70-100% is high
40-70% is moderate
0-40% is low

Remember 4 and 6 were glowing
#2 indicated 15%
#4 indicated 17%
#6 indicated 22%

 

Have you tried cutting out some fuel? Or found roughly what the afr is at idle?

 

Yep, I have pulled out fuel and the wide band in the car says A/F is fine.