Bear with me on this, because it's a crazy turn of events....

A neighbor's son came by in his Pro-Touring '66 Mustang last Sunday. We started talking and I ended up pulling the Camaro out of the garage. Apparently, the rear fuel rail cross-over was leaking fuel and the only thing I can think happened is that a spark plug arced and ignited the fuel. Next thing I know, there's smoke pouring out from under the hood!! I open the hood and the rear part of the manifold is on fire!! Fortunately, he had a fire extinguisher in the car, so ran back and grabbed and put the fire out. Needless to say, I now have an extinguisher in my trunk...

Anyway, after I cleaned evertying up and replaced all the melted vacuum lines and wire looms, this prompted me to revisit my plug wire arcing problem (I could literally see a light show at night). I actually noticed the arcing a little while ago, then changed from the L98 Corvette wires to some Taylors in attempt to solve it. The arcing somewhat went away since I went through great pains to separate them out, but overall it didn't completley cure it. So out of shear frustration, I kinda dropped it for a while. Then, over the weekend, my car freakin' catches on fire due to a fuel leak and austensibly a wire arcing to ground and igniting the fuel.

Well, I posted about it on the second gen Camaro site and a guy over there asked me where my main engine ground was located. I had it on my serpentine bracket for a long time now. He suggested I relocate the ground to the cylinder head....



That immediately solved the arcing problem right then and there. And... AND... I think it solved the idle misfire! I'm still in the process of confirming it, but so far it seems to have cured it. Idle is smooth and there's no rotten egg smell anymore!!!

All I can think of is that the ground point on the serpentine bracket had too much inductance during ~high speed discharging (almost like AC current), essentially acting like high resistance (even though it may have had a good DC ground under steady state current). Every time I checked my grounds with a multi-meter, I always got excellent results... less than .5 ohms. There was never any indication that I had a bad ground. My spark tester always showed I had good spark. Even the professional shops that checked my ignition didn't see it.

I was so convinced that the manifold had distribution problems that I was going to swap over to an LT1 PCM. I would have ended up right were I was before.

Geez, it took an engine fire and a shot-in-the-dark post from someone I never met before to finally cure this four year old problem!??


BTW... I e-mailed TPIS about the rear cross over tube. Mine can shift back and forth between the rails. So if I don't center it up, it'll leak. TPIS says it's not supposed to be like that. Does anyone else have this problem with heir Minirams? They're sending me out a couple of new ones in case mine is in fact too short.

 

Good Luck! I sure hope this solves your problem, I know how frustrating some of this **** can be. Guess I'll check and clean my two cylinder head grounds this weekend.

Doubt it will resolve my split BLM problem, but hey, stranger things have happened....

 

Better yet, use a starter bolt for the ground lead.

Plugs, and the ignition system are just taken for granted. Most people think that if there's no miss, things are fine. I've posted here about ignition stuff, and they're just ignored.

BTW, you might also want to run a *ground* from one head to the other, and then a lead to the battery, or chassis ground.

Some of the ****** mags have had articles, about *Grounding Kits*....

 

I never thought of a ground tying the heads together, but that's a d@mn good idea - especially if you stop and think about a leaking VC gasket that drips onto one head's ground. Regardless, tying them together sure can't hurt anything. Since they're both tied to the firewall/chassis ground, another tie-in to the battery negative terminal can't hurt anything either, right?

Guess what I'm going to be doing part of this weekend.....

I can't figure out my 1.0-1.2 AFR variance between banks of the motor. The SuperRam has been off and on 3 or 4 times, always used new gaskets (the "correct" ones), sometimes with RTV as well, but this driver's side rich variance has ALWAYS been there. So it shouldn't be a vacuum leak I would think. The injectors are SVO 30's that were cleaned/flowed less than 1000 miles ago by Rich. Plugs and wires have been changed a couple of times trying to run this down as well. Header gaskets changed at least twice, and the header-collector gaskets at least once. Occurs with different O2 NB sensors as well. So I guess I'll be checking the grounds this weekend in case that is causing some injector firing anomaly.

 

Based on your advice, Grumpy, I think I'll tie one of the heads to a starter bolt as well. Then they're all tied together and to both the chassis and the battery. Might even do a collector bolt on each side as well. Hopefully this will somehow help.....

 

Grumpy,

Yeah I already did that. I figured if one side had a grounding issue, then the other head is going to have the same issue if its not grounded directly.


I still need to do a couple of other things like remove the 30lb injector from the #2 cylinder.

I REALLY hope this turns out to be the solution.

 

Good to hear that you finally got it straightened out. I guess every one was correct in that you had a mechanical problem.

I see it over and over....bad grounds on cars. I always grind all block & lead connections and use a copper based anti-sieze. Always ground to electrical bolts, not mechanical & electrical bolts. Use a dedicated bolt that is not holding something together.
I have had 24#/hr injectors on the converted LT1 intake and it always idle decent on the 350ci after tuning. The 42#/hrs.....ha ha, not so good...tuning to begin in about a month.

That arc problem should have been a dead give away that there was an electrical problem. I never read any posts about it. I always read about the "short runner distribution" problem.

 

Well, I put the 24lb injector back on the #2 cylinder and the smell appaers to be practically all gone. I have to literally put my nose up to the tail pipe to smell the exhaust. It's definitely a lot smoother than it was before.

I also just ran the car in pitch black again to verify the arcing problem is gone (wanted to make sure I wasn't imagining it before). It's definitely gone! Not one blue flash anywhere after running for 10 minutes.

Anyway, I think at this point, if this is truly the last Ive seen of that misfire, the remainder of the idle quality is in re-tuning the calibration. My idle block learn jumped from 128 to about 137. Probably have to put some fuel back in.

Cold start up has definitely improved for one thing.

 

Geat news - glad you foiund your problem!!!!

 

So you were basically grounding the plugs through the intake?
Trying to visualize the path.
Plugs not grounding through the head gaskets, head bolts coated with sealant not doing it well, intake bolts taking the load through the intake and then to the serp bracket and out.
kinda see where arcing from the wires to the intake (or rails) was an easier path. Head with the ground strap to the chassis never had a problem I imagine.
Connecting the heads together is great suggestion. Never looked at the possibilty of such a difficult path with all the metal around.
WOW!

 

Gotta remember the plugs work on A/C.
Not D/C.

 

Exactly. So now inductance plays a role in the overall impedance of the circuit. Bolt threads are not a good ground for this AC current. Especially black oxide coated head bolts!

This little debacle has really driven home this point.

 

Yes, and both power leads and ground leads can carry the A/C current. A/C current follows the path of least inductance.

 

Wow, i've read your past posts on the problem. Glad to see it ended up to be a easy fix. Just too bad you had to chase it down like that.

 

Yes.
And, you have to realise that A/C is a *sine* type wave, that swings thur *0*. Unlike D/C the just hunts for ground. So a *ground* problem, with A/C, occurs with every swing of the since wave as it passes thur ground.

There's no such thing as too much attention to detail, when it comes to ignition.

After all a CDI based ignition with one CDI per DIS coil should perform the same as a CDI firing a seperate coil per cylinder if in DIS mode, right?. Bzzzzzt, there's a signifigant difference.

 

And capacitance......
It all matters.

 

Well, it's definitely fixed. I just got back from an extended drive. I think if I play around with the timing a little, I can get it dead smooth. No smell anymore either.


Wanted to say thanks to everyone who's been helping me through all of this over the last few years. What's amazing to me is how much impact the internet has on hot rodding. I probably would have NEVER EVER thought of this solution in a million years on my own!!

 

Well glad to hear that you got your problem fixed.
I started thinking about grounding the heads on my car but apparently they come like that from the factory. The only thing thats different is that they go to the firewall for a chassis ground. I would imagine that this would be good enough, right?
The only other thing that I could thing to do would be to clean up the ground between the battery and chassis(right now its just a small lead off the terminal that grounds to the fender).
Is this good enough or am I missing something.