Misfire

[dogboy]

Kinda. It comes on at random and the code is for "engine bank 1 sensed lean" or soemthing like that.
It has done it every so often since I got the truck 2 years ago, but it becoming more frequent now. It would come on once every month or two when I got the truck, and has slowly progressed to 2-3 times a week. It will come on and go off at random. It can come on and be on untill I turn the engine off, or sometimes it comes on and goes off in 30 seconds, then will come back on half a mile down the road, sometimes it will go out and not come back on. It is truely random.


In town, if I can keep the rpm's above 2500, kinda like you siad, then it runs pretty much just fine. But, that probably annoys pedestrians, and me too for that matter.

 

[dogboy]

Well... I feel liek a huge moron...

I cleaned the Mass Air Flow sensor, no change in the way it ran. Cleaned the IAC vavle, still, no change.

Looked at the air filter...... That was a suprise!! Imagine the air filter CAKED with 1/4" of mud, and being creased because the motor was trying to suck it in!

It was a K&N, so I cleaned it up, and the creases pretty much went away. The top of the filter was clean, so at least I know the filet was doing it's job really well, I just wasn't doing mine.
Sad part is, is that the mud from offroading the first weekend in October. I forgot to fold the intake up and ziptie it to avoid this type of thing
I'm changing the plugs tomorrow becuase it is pretty much solved, but it is still slightly there, barely noticable.

 

[97ranger4x4]

I wish mine was that easy to solve...

 

[dogboy]

Have you tested the plug wires, or are you just changing them or what?

I'd test the wires if I were you. They should be at or below 7000 ohms of resistance, per foot. The passengers side wires are right at 1 foot long, and the drivers side are just over 2ft long. Or at least that was the measures on mine.

 

[97ranger4x4]

How do you go about testing the wires. Do you just set the multimeter to OHMS and put the red lead on one end and the black lead on the other end with it being out of the truck?

I was planning on ordering a new injector today off rock auto, so it would be here by next week. I am pretty much slammed with school and cant touch my truck for the next week

 

[dogboy]

Yep, that's how you test the plug wires.


I don't know what the costs would be, but it might almost be worth it to take it to a shop, and ask if they can clean the injectors for you. I bet it would be alot cheaper than new ones!

I know a injector cleaning machine will clean them way better than seaform, or injector cleaner will.

I thought the air filter solved my problems... Nope. I'm still on the search for the cause still, I guess. The truck didn't have time to warm up completely the first time I tested it.

 

[97ranger4x4]

yeh as much as I hate to bring it into the shop, at this point I will probably just call some local shops and see if I can have them all cleaned and tested.

Thanks for the advice. Hopefully your truck gets running back to normal soon.

 

[mkparker]

Any new news here guys?? I have a '91 4.0 that is doing very similar. Runs like crap when cold, but once it warms to normal it does better. Still a miss there though. Cool it off and it's bad again. I have brand new Motorcraft wires, plugs, air filter is good, clean MAF. I haven't changed the fuel filter ever, so I'm suspecting an injector also. No CEL. You guys find anything?

 

[Sasquatch_Ryda]

Could be a bad wire or even a bad coil

 

[97ranger4x4]

Well mine ended up being a bad plug on Cyl 1. It must have burnt or cracked the porcelin inside the plug because it looked perfect on the outside.