I almost replaced the timing chain. I have a really good one, a roller, but when I dug it out to swap it, it had rusted very badly. I know timing chains wear and it causes timing problems. I wish there was a definite diagnosis of this 1,3,5 mis-fire problem.

I have some vacuum leaks. The small hoses, there are 3 of them coming out of the top/center of the firewall have dry rotted, and oddly enough it caused the trans to shift into neutral when under strong acceleration. Repairing these small hoses has the trans shifting like a pro, but I'm still having the problem of the AC switching from vent to floor when I accelerate, so I suspect there is either another vacuum leak somewhere, or that a check valve has given up.

 

Well, my '98 3.9L only had 78K miles on it when I bought it last June so I sincerely doubt the timing chain is the culprit, at least in in my circumstance. Records received with my van at time of purchase show regular oil changes at 3-4K miles, so it was well cared for.

I guess the chain is easy enough to change but I would not expect it to solve the random misfire MIL situation for anyone here. Has to be something else.

Also, FWIW, my plugs were the very first thing I changed, so I know without a doubt that the No. 8 plug is OK. They're all OK.

Maybe the brand of plug has something to do with this? I have NGK Platinum plugs in there and I'm considering going back to a more Plain Jane plug -- closer to what the factory used.

Anyone know what that was?

 

I don't think it could be the plugs. If there were some randomness to the cylinder misfire I could believe it, but the fact that it's 1,3,5 All on the same side.

My first thought was fuel. The fuel delivery is divided into two parts, left and right. The L getting less direct fuel than the R side. I was thinking that a dirty fuel rail, clogged filter, or weak fuel pump might deliver more fuel to the R and less to the L. However, I see that there is a code for lean mixture, and it's not the same as that for misfire.

Bill, speaking for myself, I like to hear from anyone who has something to contribute.

One poster said he cured this prob with the high dollar wire set, I'm up for giving that a try. I appreciate a good wire set anyway.

 

Well, the little sticker uner the hood of my 3500 with the 5.9L says the plugs are RL12LC4 .40 inch gap. I think these are champion plugs, I could be wrong though.

I also heard from a fellow van owner that sometimes the fuel rails rust from the inside out. If I remember right, fuel comes in on the drivers side and then is transferred over to the passenger side by the fuel bridge. It's the semi-flexible rubber tube at the back of the engine.

I'll try and post the list of what I've done sometime tomorrow.

 

Tried the Champion plugs, didn't like them. They seemed to fowl quite easily. (Also tried Autolite, didn't like them either) Prefer the Bosh platinum. My old mechanic hated Bosch, but my experience with them is they last a long, long time and resist fowling, and I don't care if he likes them or not, they work very well for me.

I'm going to investigate the fuel rail next time I pull the cover. Would love to replace the injectors but cost is prohibitive.

Been going through the codes one at a time. Had a 02 sensor code, but I was able to pull it and blow it out and it returned to good status. Right now I'm trying to do the same with the rear but it's being a real problem coming out. 7/8's is a bit sloppy and has rotated on the sensor and i don't have a 22mm. Not sure what I'll do yet, likely go buy a 22 and give it a try. Think they also make a half drive socket specific to 02 sensor removal. Think I could also cut the wires and slip a socket over the nut, but I hate to do that.

I'll report in if I make any progress with the 1,3,5 problem.

 

I feel the same way. Something you could try is swapping out say the #5 and #7 injector or potentially one from the other side and see if the misfire will follow injectors. That's what I did but no such luck. That way you can make sure it is the injectors before wasting your money in new ones.

 

Been there, done that, it didn't help one bit.

 

AC Delco should be gapped to 0.35 which is a different gap size to the original spec

 

there seems to be only a few things left to do and that is to start removing sensor wires and see if one of them is causing a problem. there is a temp sensor by the AC unit which I recall was causing problems for someone.

I found this on a Ford Forum

http://www.f150forum.com/f6/engine-m...-2-lean-92599/

Here are some more ideas which may be possible

https://dodgeforum.com/forum/2nd-gen...-solution.html

http://www.engine-misfire.com/

seems to be a good 101 on the problem.

 

Thanks for the link! Found this:
"I had a chance to pull of charcoal canister today. Three hoses connect to it. Hose to tank is fine. Can blow into tank hose pressure blows back. Vent hose from canister to back of engine is clear. Hose from canister to purge solenoid is clear. The canister itself appears to be functioning properly. So that leaves the purge solenoid. This is a $38 part at autozone and will be replaced in a day or two. Change the purge solenoid if you have P0300,P0301,P0303,P0305 misfire codes on cyl. 1, 3,and 5."