Two plug wires were crossed. Beer + working on car = BAD!



Here's the deal, my 94 Z28 A4 with 83k miles has a miss. I had the transmission out of it a couple of months ago. So while it was out for a rebuild, I decided to change my leaky water pump. So, I also installed a new otipspark (AC Delco brand new), CSR waterpump, new sparkplugs, and just recently new otvc plug wires from elite, also a new fuel filter. Been missing on a cylinder ever since. Today I pulled plugs out of the drivers side. They all looked like brand new still So, I proceded to pull plug #8, it looked good, and #6, it was carboned up. So, it seems to me that #6 is not firing right. I put a new plug in, and it still misses. Got pissed and decided that pulling #2 and #4 would send me over the edge.
Also diconnected the O2 sensors to force open loop, and it still has the miss. No check engine light, ran fine before I replaced all this stuff. No arching wires or coil at night in the dark either.

Is it possible the optispark isn't firing #6 cylinder all the time, therefore making the plug look black? How can I diagnose this? Can a shop look at it and tell right away if its the opti or something else?

 

might have a bad injector on #6.....put the wire up whare you can see it and start the engine, check for spark

 

It's probably not your opti. I wish people would really quit blaming them for everything.

 

Thats fine, I can go with that. But what else can it be? Seriously, the car ran just fine before I put the new optispark on.

 

But it ran fine before all this repair. I still started the car up once a week or so. Could an injector have gummed up because of that?

 

It's a spark or fuel problem. I'm chasing a few right now too.

To answer your question... maybe... or perhaps a piece of trash made its way into the injector when you changed the filter. Isn't hard to deposit a little piece of dirt or something in a fuel line while handling it.

Did you check for spark at #6?

-Mindgame

 

Take a piece of #10 wire and skin it back a couple of inches. Run it from the opti to the #6 plug any old way(routing) and wrap it around the end of the plug. Peel the individual wires back on the wire for the opti end. Crank it and see if it still misfires. If it runs OK it is the wire.
Yes, it will fire with the regular wire and not hurt a thing. Just a test for plug wires when ya don't have long ones laying around.

 

As far as the spark is concerned, you can use an inductive timing light to see how consistant the spark to that plug is. You can also swap the plug wire from another cylinder.

It's probably not a fuel problem since you are getting carbon build up on the plug. You can eliminate the fuel issue by swapping injectors. But there are other reasons a cylinder could be misfiring other than spark or fuel. It may be time to check compression and do a leak down. A tight rocker arm for example could keep a valve open too long and cause a compression problem. As well as carbon under a valve, burnt seat. The list goes on.........

 

Well I just changed plug wires twice because the first new set was bad. This set is not leaking spark anywhere. Sorry I forgot to mention that.

I did have a rocker arm come loose during my initial test drive after all of this. It was clacking against the valve cover, not hard to do with Crane Energizer 1.6's. I re-adjusted it and tightened it down. I can't imagine this would be the problem since it was missing before it came loose.

I'll check into getting a timing light from a friend to see how consistent the spark timing is on each cylinder.

 

Maybe its just my imagination, but it seems to run real rich. The exhaust smell is pretty strong. It has no cat, so I smell everything. But I don't remember it being this rich smelling.

 

When the ignition cuts out, you will be running ruch due to the unburned fuel. I have also seen instances where the metal plug boot shields cause the ignition energy to ground. I ended up having to remove mine and replace them with taylor firesleeves..... that fixed it.

 

I understand about the rich smell. Also, no metal plug boot protectors.

 

Sounds like a bad wire to me: If it didn't miss before the opti change and the plug change and the wire change and now it is just not firing on (1) cyl. I'd guess you are just not lighting that cyl. Make sure the plug is not broken and the wire is good before you tear into anything else. JMHO

 

Stupid thing is in the shop now. They'll diagnose it for me tomorrow with their machine. Ran even worse today than it did yesterday on the way to the shop.

 

update, see my post up top.