Sorry about the confusion on the timing order, I meant to represent the sequence on the distributors in hopes of drawing a possible correlation between the missing cylinders and the distributors and their systems such as the coils. But alas, it was not meant to be.

I’m going to try testing the spark and see what comes from that, my guess the spark will be fine in all cylinders. Which leads me back to the fuel system. I guess I gravitate to that because it affects all cylinders and if it is contaminated fuel, won’t cost allot to fix. The other possibilities such as valve train sound pretty costly. Think happy thoughts.

I’ve given myself until the end of today to troubleshoot this, if no luck, the car and I will be at the mechanics first thing in the morning.

Thanks again for all the help, please include any thoughts you may have, so far they have been very helpful.

Paul

 

Paul,

I prefer to think of the firing order as 3726 5481...3726 5481...3726 5481... It makes more sense to me. Looking at the engine, this order alternately creates a "Z", and an "X". If you do not see your firing order as we all have suggested, then maybe you inadvertantly swapped a couple of wires???

Sorry to everyone if I didn't "dumb it down" enough in my previous post about pulling the wires... Obviously protect yourself against getting a shock... Pull the wire off the DISTRIBUTOR CAP. Loosen them up before you start the job & only do it briefly... enough to sense whether there is a change in rpm or not, but don't leave it running that way while you go get a cup of coffee, etc.

Another, more thorough way of testing the system is to pull a spark plug wire before starting the engine, put a spare plug into the connector and ground the body of the plug in such a fashion that you do not participate when the engine is running. Start the engine and use a diagnostic tach (accurate, low range) to measure rpm for each pulled wire. This method may also help detect problems with the wires.

Paul, have you done a compression test?

 

No unfortunately I don't have a compression gauge, it is a hole in my troubleshooting.

Paul

 

If it's any consolation, they're relatively cheap at your local auto parts store. With a little luck, though, you will find a problem with your high-tension system instead of a mechanical problem (shudder, shudder).

 

Time got away from me yesterday and I didn't get back to the car. That's what happens when you have allot of kids. The car is now at the shop and I may know the diagnosis by mid-morning. Keep your fingers crossed, I'll let you what the outcome is, hopefully it will help someone in the future.

Paul

 

I STRONGLY recommend that you NEVER operate a 928 ignition system with a plug wire disconnected - anywhere, either end, any way.

 

Looks like he was reading wires from one cap then the other, and his rotation is opposite the correct direction the way they were read.

Recommendation: If the cap need to be replaced due to wear or from carbon tracking or a crack, you stand a very small chance of curing the problem with cleaning. Replacement is your only sure option.

Many problems show up after something happens or is done. That something may be some mechanical task you did, may be shortly after a new tank of gas, or may be some coincidence that I've never been lucky enough to identify. Anyway, trace the car actions back some and think about what's been done lately and what the results have been.

Lastly, Marvel Mystery Oil is not exactly in injector cleaner. It's mineral oil with some detergents added. While it may do some good in cleaning injectors, it's better for lubricating the pump and the pintle in the injector that might be varnished open or closed. Since this is a rather instant problem you are experiencing, it's more likely that a solvent additive will do you some good, maybe Techron or a more industrial-strength verion of same.

Good luck!

dr bob

 

Sorry for the late response on this but between getting snowed in and getting the car fixed, it’s been real fun around here. Well the answer is in and the car is fixed, and to be honest it’s kinda embarrassing, there were several plugs fouled. Talk about engine troubleshooting 101, I should have check them first.

Now that I beat on myself, I’ll explain why I didn’t go right to the plugs, they were supposed to have just been changed. That’s right, I have the car tuned up a little while back and the last thing I thought is brand new plugs would foul unless there was a larger problem in the engine. Well, the plugs were never changed during the tune up. That’s the last time I use that mechanic.

I also want to say thank you all the help and guidance. Hopefully as I get back into working on the car I can contribute to this discussion board.

Thanks again,

Paul