Hi all. I have a 94 2500 v10 that has been giving me issues for a while now. We have replaced the IAC, EGR, map sensor, TPS, cam sensor (I believe that is what it is, not the crank sensor), fuel pump, spark plugs, all 10 fuel injectors... I think that's it so far. Now appears that number 1 cylinder is not firing and my dad is thinking it is a broken wire. He is going to check for loss of compression tomorrow, but what else could be causing this misfire? We have new plug wires to put on it as well, though the wires on it have checked to be ok. Any ideas I am sure willing to listen to, this truck has been giving us grief for a while now. It has 134k on it. TIA.

 

If it is only one cylinder, doing the plug wires is a good plan. (especially if they ones on there are factory originals.....) Getting any codes?

 

I don't know if he checked for codes again yet or not. He was going to mess around with it more in the morning. Sure can't hurt to change the plug wires, although he did say that the plug on that cylinder is dry - so that injector isn't pushing gas through... he is going to try to see if he can find a broken wire going to that injector/cylinder. Hoping it is not a burnt valve. This thing will be basically brand new by the time we are done! We cannot for sure say that cylinder was properly working before we replaced the injectors either (well I cannot, he may be able to as he saw it all torn apart). He did say the spark plug works as he tried that plug in another engine. Thanks!

 

Bad injector wiring should set a code. An injector that 'appears' to be working to the PCM, will not. Get a noid lite from your local auto parts store, plug it in to the #1 injector connector, and see if you are getting pulse.

 

Well, changed plug wires out and compression checks good. The light he put on injector wires indicate they are all working. It no longer stalls (was an issue that started all this being looked into crap) however, it's very rough idling - shakes like a junkie going through withdrawals now. Did have a slight idle issue prior to all the new parts and was partly the reason why the IAC was changed already, however, that was smooth compared to how it is now. Thinking of replacing the IAC again as we are just grasping at straws at this point. He has replaced everything that his years of experience has told him would be doing it. Will be replacing the coils also... truck is driving us nuts... will be 95% new engine when we figure this thing out, IF we figure it out.

 

also, it still is not throwing any codes yet...

 

Power balance test.

Start engine, let it get to a stable idle. Disable IAC. (unpug it.) Disable one cylinder at a time, and see which ones do NOT affect idle. (or, not very much) Start looking at what those cylinders have in common. (on the same coil? next to each other? etc.) See if anything interesting presents itself.

 

thanks, that is exactly what my dad intends to do Friday as my mom just had surgery today so he is busy with that. Thank you for all the input!!!

 

Let us know what ya find.

 

Well, discovered that cylinders 4 and 7 are not firing... now to hunt down why - wiring issue or computer issue? Beginning to chase down wiring now.... wish us luck. This thing has been such a pain!