[Mavericke]

So I'm going to do the work anyway. The Durango is at 200k and it's never had any major engine work. It can't hurt to be done.

I was getting a bad O2 sensor code/reading but I replaced it and it's been clear ever since. Well, it didn't clear immediately after sensor replacement... It cleared after I installed cold air intake and Flowmaster. Not sure if related. But needless to say O2 sensor code is now gone.

The only code I'm getting is "Cylinder 4 Misfire".

She misfires at low idle.... this didn't start until the code popped up.

Intake looks clean and dry. No performance loss besides mpg. She's always burned oil since I bought her at 188k miles. Maybe a quart in between oil changes? Maybe a bit more? No leaks. Seals look good. Oil looks clean. No blow-bye. I've read that typically you end up with more than one misfire code and that it's not usually cylinder 4.... thoughts?

I've done a full tune up. I've checked compression. I swapped injectors. I bought a new coil but I haven't installed it just yet.... will do so when I do the intake gasket. You guys think I'm on the right track? A buddy thinks it's probably a bad valve.... but... idk man... help me out. What else could I test or look out for? To test my intake gasket theory... I ran an entire can of the foamy spray Seafoam directly into the intake while it ran at about 3k RPMs... the check engine light flickered and then shut off for a bit. It came back on after about 15 miles. So that misfire has to be related to something - I would think!

The Hughes' plenum kit would/should fix that, right?

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Read my next response... more updates including the Hughe's intake upgrade and I STILL HAVE THE SAME CODE!! HELP!!!!
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[skitzo.d]

1 quart in 3000 miles isn't excessive for 200K miles. My new Toyota back in the day did that. If compression is good, it's not a valve. as long as the bottom of the intake is dry, I wouldn't change the plenum gasket. why fix things that aren't broke? Run some Techron Injector cleaner for a couple of tanks just for grins. Check the wires and make sure they aren't touching each other. seems this is wire related. I've had these codes in the past and put new wires on and that solved it. you said a tune up, but I'm not sure if that meant wires as well.

 

[dizzyD]

My 93 Dakota had PCM issues that related to cyl 7. the PCM have a capacitor that goes for every cylinder circuit, and every now-and-then one of these cap's go bad. Once I changed the PCM out, the misfire never returned, and after removing the silicon that encapsulated the main board, I could see the cap that went bad, dumped its electrolytic junk on the board and the heat(w/ chemical) ate the traces...Some of the New tuners out can actually measure the injector pulse, which is a neat diagnostics test for efi systems.

 

[Mavericke]

Sorry for the delayed reply... I've spent the last few weeks packing my house, loading it into storage and fitting what little I could onto my 4x8 trailer (including my Vstar) and then spent some time visiting my brother in Fort Madison, IA on my way relocating down to Fort Worth. It's been hectic... I spent all that money on my D trying to get her fixed BEFORE I made my trip to save on gas and it didn't help. Very upsetting. Very much broke now, lol! But she still needs fixed. I still need to use her as my daily driver and she still needs to be able to make the trip back up to Illinois every other month so I can see my kiddos. With the way I drive her on the Interstate, I should be getting 17mpg (which is exactly what I was getting before my problems started). I was barely getting 10mpg on my trip. Needless to say, it wasn't cheap getting here. Even at 17mpg - it was going to be tough! I will say that I was impressed that she got 10mpg while hauling an overloaded trailer. She did very very good. And that was, of course, with no overdrive. I made sure I kept that turned off with the trailer behind me. But, if I fix this misfire problem... she'll be doin great! I think I can exceed the 17mpg! But right now... no chance. Anyway, here's a recap of what I've got to work with.

So, DizzyD, very interesting.... so you think I should try the PCM next? How much does one of those cost roughly?

You don't really notice the misfire while driving her around... but when idling or at a stop-light/sign... it's very noticeable and very annoying/embarrassing. Lately, she has been acting funny like she doesn't want to fire up. Like a hesitation. Now, my battery is weak... but not THAT weak. It's like she'll kind of start to run and then almost die for a second before perking up and running smoothly (well, smoothly excluding the misfire).

So far, I still have the code. Here's what I've done so far...

• Tune up (plugs, wires, cap, rotor)
• I swapped wires from cyl4 just to be certain - code did not change, I also bought a NEW new plug thinking maybe the one I bought was bad. I also double checked the gap and it was/is right on. If it matters, I'm running the OE Champion plugs and the high-end Bosch heavy-duty, thick wires). My cap and rotor are the Duralast Gold (non-refurbs) from AutoZone.
• Duralast Gold (non-refurb) Coil Pack
• Intake was thoroughly cleaned
• At one point, I ran the foamy Seafoam spray directly into the intake while running the engine at about 3k RPMs. I used the entire can. Nothing special - I just pulled off the top cover and sprayed it in while she ran. After about half the can, the check-engine light flickered a few times and then finally shut off. Hours later it finally came back on. This is why I decided to do the Hughe's upgrade.
• Hughe's Plenum/Intake Gasket kit
• Swapped Injectors from dif cylinders to cyl4 to see if the code changed - it didn't.
• Did and ohm test on wires at injector - everything is good.
• Swapped injector with a brand new one - just in case!
• Did compression test... cyl 4 was lower compared to the other cylinders but not low enough to cause problems. I don't recal the exact numbers but it seems like the tech specs called for 115psi in each cylinder. We tested cyl4 and the two cylinders on each side of it. Cyl4 was reading 119psi and the others were reading 122/124psi. So there is a difference, but it's above specs and even if it was below specs... the difference is so small - I can't imagine that causing the problem.

Someone has to have SOMETHING they can offer me... I can't handle this. I know she's a good strong engine. No blow-bye. Strong/tight engine. Reliable. She takes good care of the family and I - I just wanna take good care of her. PLEASE someone help me out!!! I've taken her to multiple mechanics and none of them have a clue. One guy thinks it could be the distributor (which was my initial thought after the tune-up didn't fix the problem) but all these mechs said they were certain it was NOT the distributor. All except this one guy that wonders about the type of dist. that's on there. He explained it in detail which I can't remember word for word but basically something about how some of them are designed where one of the pins will get thrown off even by just a small fraction and it will cause a larger arc which can and will cause my code. He says if you know what you're looking for - you can see it when you pull the cap/rotor off. I'm an above average backyard mechanic but I don't really want to try to get back there and mess with that dist. unless you guys think it's a good possibility. Someone else told me to damage/swap my cap/rotor at AutoZone and get new ones but... the problem was happening BEFORE I swapped them out - so that can't be the problem. PLEASE!! Someone HAS to be able to help!!

FYI - I'm now in the DFW area if any of you are in the area and think you can help! You think the PCM could be the culprit?? What about the MAP sensor or the actual distributor!? I can't afford to just throw any more money at it. I need to find the problem and fix it and I'm getting desperate! Please help!

 

[Mavericke]

ugh..... anyone???

 

[Mavericke]

Ok soooo since the title is kind of misleading at this point and I've already done the plenum gasket upgrade.... I thought I might get more support by starting a new thread.

So, here is the link to the new thread; http://www.dodgedurango.net/forums/...5963-omg-cylinder-4-misfire-code-ive-tried-everything-please-help-ft-worth.html

Can an admin lock this thread and direct people to the new one? Much appreciated.

 

[FSTDANGO3]

Pcm
steve

 

[skitzo.d]

sounds like the PCM to me. look for one at a junk yard. make sure it's from the same year and security.