The ailing party- 92 Plymouth Voyager Van V6 Symtoms- misses at idle to midrange, then runs fine What has been done- New plugs,wires. Had injectors checked on machine, OK. Ran OBD on machine, checked OK. Compression test was low, not sure right now if all were low or just certain cylinder, but think it was one cylinder,I will have to get with owner to find out. Has over 100,000 miles on it, 1 owner since new. Serviced regularly. I pulled off one side valve cover, has sohc, roller cam followers, so I don't think either cam has a flat lobe. I'm thinking burnt valve. What say you?
Is it the mitsubishi SOHC 3.0 liter engine??? the valves on the back 2 cylenders like to carbon up if the PCV valve isnt changed regularly. Usually have to pull the heads to de-carbonize them. Also...Same engine... Hall effect pickup in the distributor likes to go out on em causing a random missfire. Its an expensive proposition to replace that distributor.
Gees this brings back memories. We use to pull heads on the 3 liters like mad. They would drop valve guides on the rear heads up till 90 or 91. We had to pound the guides back up and use a cutter to groove the outside of the guide for a c clip. All years had big carbon issues and they eventually burn the valve. Just condemned a 99 yesterday actually. #6 at 50 psi. You can tell at idle they feel like a very steady misfire but not a totally dead cylinder mis like ignition. Ignition misfires usually feel a bit erratic and severe. I think you'll find a low cylinder or two if you do a compression test. This is assuming you have a 3 liter. The 3.3 is a pretty tough customer and not usually valves.
As much as I pull my hair out with diagnostics now I sure am glad those days are over. No wonder my backs screwed. We use to race for time on the 3.0 warranty heads me and my buddy beside me. Thats how many we use to do. We could do a set each at the same time and race. We competed for hours bigtime. He just had to beat my times on the common jobs. 3 liter water pumps. 2.2 2.5 head gaskets. 2.5 wrist pins. Steering racks etc. The one he never did beat was my one day total. Hit 25.2 hours from 8-8. I still ride him about that one. LOL, cant even come close to that anymore. Thats when we used to make good money in the 90's.
LOL...25.2 HRS...Your an animal!!! I like being paid hourly. 2.2/2.5 head gaskets...I used to do em in an hour flat and running, burping the cooling system. Unless they got heated soo bad that the valve guides dropped out of the head...Man those heads could take some punishment. Of course if you had em with cracks at the jackets well you know...I just like not being the only markanic where I am at now...Did 10 yrs at the last place all by my lonsome...Of course my boss was entertaining at times and tended to keep me busey with his screw ups...LOL... Ahh the days of wine and roses...AKA getting paid well weekly instead of just getting paid...Weakly...LOL...
I think you have nailed it! Just got through talking with the owner again. It's a early 94 instead of a 92, 3.0. She said one cylinder had low compression, but she couldn't remember which one. You describe exactly what I'm feeling, misfire at low speeds, but not a dead cylinder because it will pick back up and run smooth. The van has 158,000 on it, one Lady owner in her 60's, never driven hard. I had ruled out just about everything but the burnt valve, so you have confirmed my findings! Thanks much! I gave her my thoughts on it , so now she has just got to find somebody to tackle the job. I no longer work on FWD stuff, just not enough room in there for my big hands and I skin up too easy anymore.
Before I hurt my back I was an extremely fast tech..... My record for flat rate labor turned in a day was 41.4 hrs It was honest. I started at 7 am and went home at 11 pm That was 2000. If there was any cars left I would have just stayed...lol Best check I ever got from this business at a shop came that week!!! I got my assistant manager bonus I got once a mth as well.....I could have built a healthy motor with that check!!!!and then some
oh oh oh cant believe you are forgetting a very common issue on those.....wiring harness on the injectors rubbing through and misfiring....sometimes they act like he describes but more times than not they mis when in gear only when the harness gets stretched w/ drivetrain movement
Thats insane. LOL. No wonder we all have bad backs. Tough way to earn a living. I do miss the money but it came at a cost.
I've done many for that but they were all 3.3 liter mininvans 96 and up. They melt the harness together beside the coil pack. Dont remember 3 liters doing that. Long time ago though.
3.0L rub through from the harness movement when the engine torques forward or back under load...... and I never even came close to that 40 plus hrs again lol I did some 20 hr days for sure though these days 40-50 hrs flat rate a week is hard to come by
