Ok let me first give a little background to the problem. This engine uses a custom harness so it can fit in my truck. When I bought it, the previous owner stated that there is a problem with the part of the harness going to the coil. Once in a blue moon, for no apparent reason, the engine would just shut off. And the only way to get it running again is to unplug the harness off the coil and coil module, and plug it back in. It sounds stupid, but it has cut off a few times on me in the past, and that fix worked every time.

Last night I want to go out, and the engine dies 3 times before I can get out of my driveway. However, every time I go in there and do the fix, it starts right up. So I head out, and I'm getting on Route 287 (6 lane highway by me) and it does it again. So I sigh, roll out a bit to get to the shoulder, and pull over. As soon as I pull over I noticed something and a lot of smoke came out from under the hood. I just realized that the coil had shut off again, effectively killing the spark, but the enigne continued to run! I didnt even think of turning the ignition off, because usually it doesnt die when Im doind 75 on a highway. This time it somehow managed to keep spinning (even with a 2800 stall, not a stick), and it was pumping straight fuel into the cylinders and exhaust. All I could smell was raw fuel when I opened the hood, and I fully expected a fire to be there, but fortunatly, there wasnt.

So by this time I am fed up, and I bust out my tech bag, and start cutting into the coil harness to see whats up. I turn out finding a couple of hidden splices that had been soldered and taped, but the wire was extremly corroded under the insulation. So I cut back to where I could find some good looking wire, and spliced it back together with a crimp on butt splice just to get me going again.

I figured that I had solved the problem of the intermittant coil, and everything would be good now. However, I get back in and start it up, and it fires right away, but its idleing at 2,000 rpm! It sits there for about 3 seconds, then slowly makes it way back down to 650 rpm, where it usually sits. I figured this was no gid deal, probably all that excess fuel burning off...

So I get going back down the highway. First off, my exhaust tone is MUCH louder, and it sounds like I have a gaping hole in it somewhere. I have a problem with sealing the headers, and I just put in a set of Felpro gaskets back in May, but the bolts walk out all the time. Anyways, thats the least of my concerns, because I get it back up to speed, 70-80 mph, and it is vibrating a lot more than it used to. Especially when I get off the throttle and let it coast on the higher rpms, it vibrates A LOT. Also, performance feels like crap, it can still run, but it doesnt feel good like it used to.

I think I fouled every one of the spark plugs, and maybe toasted the o2 sensor with all that excess fuel. I dont know where all that smoke came from when I stopped; Im guessing maybe out of an exhaust leak at the header. The engines not spitting any codes right now, but it is definatly not runnign up to par. Maybe the quick splices I made is messing with the resistance or something and the computer is messing up the timing? Please help me out if you have any insights. thanks guys, lata

 

ok pulled some stuff..heres the pics:





these plugs were just put in late May, and now they look like butt.

heres my ignition mess thats causing all these problems:



any idea where i can get new harness plugs for the coil. they look like this:



anyways im gonna switch out the plugs tomorrow..its raining on and off outside right now...

 

whew. thats weird.

the fuel gushing in could harm bearings. make sure the oil is ok.

there is a chance that the opti may have been fried by all the coil related problems, as too the ecu.

 

I think one of the first things to order from Jeff, is a new harness. I would sh-- can the old one as it is a known trouble maker..... and it's a lot cheaper than a fire. I know it's a stupid question but was it running or dieseling? Those plugs look fried.

 

good call on the bearings..i thought of that too and check the oil but i didnt notice any fuel in it...

ok, who is Jeff? and where can i order the new harnesses, cuz thats what id like to do. when the coil shut off on the highway, it wasnt 'running' but the engine was definetly spinning. ya i know those plugs look toast, and theyre only 2 months old.

 

Jeff (carfan18) can be reached at 1-800-728-8267, tell him you are a forum member. :yesnod:

 

ok, who is Jeff? and where can i order the new harnesses, cuz thats what id like to do. when the coil shut off on the highway, it wasnt 'running' but the engine was definetly spinning. ya i know those plugs look toast, and theyre only 2 months old.[/QUOTE]

Jeff Koop @ Superior Chevy. 800-728-8267. Tell him your a forum member for a discount on prices. Has been good to a lot of guys here.

Also, you might try, http://www.gmpartsdirect.com for a competitive bid. However, they have a "funny" return policy according to some of the members.

I've used Jeff before and he has been way cheaper on parts.

 

Your gonna replace the whole harness because of a bad coil connection,...... :confused: That is expensive proposition. It would be a whole lot cheaper to get the factory service manual, and verify the wiring. We are only taking a few wires here. If you live in the rust belt, (NJ), and you used just a simple crimp connector, there is a good chance they will corrode again.

And,... what is so bad about those plugs?
They are the correct heat range, and they were firing.

The vibration and loss of power tells me you probably dropped a cylinder. What do the rest of the plugs look like?

 

a lt-4 in a truck! :cool: good luck fixing it. :cheers:

 

no no, perhaps i am misunderstood. i just want to replace two connectors and wires that i have pictured, not the whole harness.

also, maybe you did not read thru my book, but i stated how it shut off on the highway and i made those butt splices just to get it running again. i have all intentions of soldering it and heat shrinking. im not stupid.

i really hope i didnt drop a cylinder...i dont know what the other plugs look like, because all the rest of them are a total b!tch to take out. like my man said 'lt4 in a truck? good luck fixing it'....

thanks for the heads up guys, ill give Jeff a call