Testing fuel injector harness...

[Hozer 88GTConv]

I still have too much fuel getting into one cylinder. The plug is flaky, sooty, and black. The electrode is chipped too.

I have rebuilt the heads and it's not oil. It is definitely fuel and I know I'm running rich to boot.

It's not a leaky injector, unless they all leak, because I have swapped them several times.

So, I'm left with the possibility of a malfunctioning electrical harness, or an O2 sensor problem, or both.

I am going to torch-clean the O2's and check the readings with a meter as they heat up.

I have no idea how to test an injector harness.

Any ideas?

[canukracer]

buy a noid light, they are cheep, plugs in at each injector crank over or running will flash if wiring is working.

[HISSIN50]

Originally posted by canukracer
buy a noid light, they are cheep, plugs in at each injector crank over or running will flash if wiring is working.

that is spot on. shadetree folks also just listen for the clicking of the injector, meaning it is actuating (how much it flows is not known with either method).
another angle to look at. you are seeing the result [on the plug]. are you sure you have good spark to that cylinder? that could also lead to the description of the plug you have (not enough spark can look like rich).
anything else wrong with that pot? signs of detonation, etc (i know you said you run rich, but...)

i would not worry about the O2's unless you have a whole bank running funny. an isolated pot being weird is just that - a problem with one cylinder......the whole bank's plugs would be funky if it was a lambda.

good luck.

[Hozer 88GTConv]

The rest of the banks plugs look great. It's just number 5.
I have changed the spark plug wire too, just to make sure, but it still has crap on it.
It has to be a malfunctioning wire harness, just leaving the pulse on too long. I have changed/checked/swapped everything else at this point.
Thanks for the suggestions...

[tireburner163]

What does the terminal look like under the cap on #5?\

I would think it was spark rather than the wiring harness. I just don't see how a harness could malfunction. Short and not work, yea, but I don't see how it woud make the pulse width too long. The EEC yea, but not the harness




-Josh, aka the tireburner

[Hozer 88GTConv]

I r/r my intake manifold again. With 1250's there seems to be a little oil coming up from the lifter valley on number 5 underneath the gasket.
I put new ones on with a silicone bead around the intake port on number 5 to boot. Hopefully that'll take care of it.
Everything else looked good.
Still runs rich as hell, got fuel pressure down to 35 psi at idle w/ vacuum off of fpr.
Oh well, enough for today. Going to re-adjust the timing, it idled pretty low, think I'm off a couple of degrees.
I'll let you know...

[7K331]

Generally If you have a harness problem the control either works or doesn't. Check the continuity of each injector wire, if they all check out close try one of the following.
Complicated:
For about 70 bucks you can get multimeter at Radio shack that will allow you to read pulse width. Youget software with it that will allow you to data log. You could wire this up to read various injectors at specific rpm & compare.
Easy:
Simply borrow an injector harness fro a car that works.

[HISSIN50]

my brain is not working (happens often). a balance test should show wiring and/or injector problems.....
neat test if you have not done one. the 'puter will check injectors, and if a fault is found, it retests using different criteria. it will test 3 different ways, so you can try to pinpoint the problem......i would try a balance test next.
good luck.

[tireburner163]

Autozone, NAPA, Advance, etc sell a gasket shelack(sp?)

It's a dark brown substance that dries semi-hard. It works great. I put around all my runners on the intake.



-Josh, aka the tireburner

[Hozer 88GTConv]

Autozone, NAPA, Advance, etc sell a gasket shelack(sp?)

I have never heard of that before. Damn, that would've saved me some headaches.

Burner, why do you use it? Does you draw lifter valley oil into your runners too?

I am curious if anyone else has this problem. It has to me more common than I think. I don't see how high-performance heads can't pull from the valley. That seems to be a weak gasket point.
Of course, it could be my several years old GT40 intake manifold has warped a coupla thousandths too.

[tireburner163]

this is the stuff I use

http://www.usahardware.com/inet/shop...xinc/20539.htm



-Josh, aka the tireburner

[Hozer 88GTConv]

I'm ordering some today....thanks for the link.
I want to eliminate this once and for all.
(After ump-teen gasket swaps...)