Hello, help and suggestions please. Check engine light - code read #4 misfire. I replace all wires and plugs. All fine for one week. Engine misfired at start up then smooth in a minute or so but check engiine light again. Code read #4 misfire again.

Which cylinder is #4? I will check loose wire, plug.

Suggestions on what else to do, check and how?

Jim

 

What engine? The cylinders are numbered front to back, passenger side of truck is 123(4), drivers is 567(8). hope this helps. If it's a V8 it's probably got the COP ignition (coil over plug) system. The COPS tend to go bad and through the timing off.

 

Sorry, yeah, a 6 cyl. no COPS. So front to back makes driver front # 4?

 

Good luck, a miss fire code tends to mean that you have bad plugs all the way around.

 

I did change the plugs and wires after the first "check engine soon" light appeared. Then I got the same message after driving about a week with no problem. Do you know which cylinder is the #4 in the 6 cyl?

 

Yeah, it's the drivers side, front cylinder. Does it have a distributor cap or coil packs? It might be a bad coil pack.

 

I think the V6 still used a distributor. If so, check the cap and rotor. If the wires needed replacement, most likely the cap and rotor did too.

 

Thanks Clubwagon. Apparently the 4.2l has electronic ig. since there is not cap and rotor listed for that vehicle. So I am still looking for advice on how to proceed. Again I will state the problem as I may not have been clear previously.

Serivice Engine Light (SEL) came on and I had the code read. Said #4 cyl. misfire. So I figured time to replace all wires and plugs (140000 mi.). I did so and all went well for about 1 week until the SEL came on again. So I had another reading done and again same code came up saying misfire #4 cyl. When I start the van the engine runs rough as it is missing. But I wait a few minutes - maybe one minute and the engine runs smooth with no apparent power or rough idle. Of course the SEL stays on. So every time I start the car in the morniign I experience the same conditions.

I don't know which cylinder is #4. Anybody know. I am gong to check to see the connections to that cylinder and the plug is tight. Any other suggetions? Thanks - Jim

 

Well, it can have electronic ignition and still have a distributor. If it doens't then it has individual coils, although not a "coil on plug" arrangement.

From your symptoms, I can assume one of two things is happening: 1) the coil pack for #4 is failing and needs to be replaced. Or: 2) there is a problem with that cylinder. When you start it in the morning, do you notice any blue smoke out the tailpipe right after startup or as it warms up? If so, you could have a bad valve stem seal that is leaking oil into the cylinder and causing that startup misfire. Or, you could have a leaky injector that is fouling the plug on startup.

 

Good information, thanks. I called the dealer and he said no rotor or cap is called for in that model so I assumed that to mean no distributor? I will certainly check the smoke in the AM. Also, none of the old plugs seemed to "bad burn" signs. I guess oil in the cylinder would show up as black carbon on the plug?

Does the following help to tell whether this is distributor or . . .?

 

That's a coil pack. It'd do a compression check. If that cylinder shows low compression you've got an internal mechanical failure. If it's up to par with the rest it's either a bad coil pack, wire or a sticking injector. Like I said in my first post the cylinders are numbered as follows. Front to back, Passenger side is 1 2 3, drivers side is 4 5 6.

 

Good suggestion, thanks. I guess I have to put some more time i before I take any place long distance.

Jim