90FormulaL98

Only one tube is glowing. I just noticed it today could have been doing it for a while now. Just dont know. What causes this?
Thanks Gary

8Mike9

Just one tube,? My guess is that one injector is dumping too much fuel into the cylinder. The excess fuel is being reburned in the primary, and causing it to glow.

Now sit back and wait for the "lean" crowd to come on in.

90FormulaL98

lol you are right. Well could it be that i am not getting spark in that cylinder so the gas is not burning. I dont know what to think, it runs really good has a small miss but runs good. how would i check to see if it is my injector or the spark in that cylinder?
Thanks, Gary

88 350 tpi formula

iTrader: (9)

yep, you got it I am guessing lean... and yep I beat the inj, would be the cause, first check the wires to that inj. then you can switch the inj with another cyl. or if you can get a inj tester and compare the fuel psi drop vs. the other cylinders.

8Mike9

Yes, could be weak spark as well. A quick search for 'how to test for weak spark" would save me a lot of typing

Raiden

Pull the plug! read the plug in the cylinder that is glowing. That can tell you a lot! Also, chekc the voltage on the injectors...all of them.

90FormulaL98

Check the voltage on the injectors while it is running or off, and what is it supposed to be?
Gary

8Mike9

Okay, let's keep ya on track as to what is happening with the cylinder in question...

Check the plug...most likely it'll be a little bit "sooty"...but why? Too much fuel or too little spark (discounting a bad valve causing exess fuel to pass through)?

Next, check the voltage on the injectors...my hunch is you'll always see 12v.....and that would be correct, because they always have 12 on'em until the ECM grounds the other side to "fire/open" them to allow fuel into the port.

You can diag the problem efficiently by...


1. Compression test. This will eliminate/comfirm a valve seating issue.

2. Injector balance test, this will tell you if that injector is dumping too much fuel.

3. Spark test. This will tell you if you are not firing the cylinder well enough.


Now...is it lean...I really don't think so..why? Well, in order to "glow" the tube, the heat from the combustion chamber would have to be sooooooo high, you'd probably melt the primary....Sure, if the primary was "red" just off the head, could be lean, but if there is any "length" to the "glow", 99.99999999% of the time, it'll be from unburnt fuel.

And just think about it, I'm guessing (may be my mistake) that "you just noticed" this...when you popped the hood...when the engine is idling. How the heck could an idling engine be so lean to glow a primary?...Impossible, IMHO.

bubafett

It is not lean.
There is fuel being burned in the exaust.
either a leaky injector,
late ignition,
leaky exaust manifold
burnt valve...

spartyon

i would venture to say its valve timing. either the valves are staying open to long or opening to soonand the spark ignites the fool as its exiting the cylinder