Lean codes, now a misfire?!?

MyNameIsAaron · #1 03-16-2014, 03:08 AM

I have a 2000 4x4 V6 OHC. I had both lean codes and decided to try and fix it. I unhooked the battery, unplugged the MAF sensor, and cleaned it using MAF sensor cleaner. I followed the instructions to the T and never touched the hot wires with anything other than the cleaner. After cleaning and replacing said MAF sensor, I cleared the codes. On the way to work today I could tell it was misfiring. Sure enough, on the way home the check engine light came on. I pulled over, checked the codes and bam! P0304... Cylinder 4 is misfiring and I don't know what the hell the problem is. I'm assuming a possible vacuum leak, but this code was not present before and now it is.

Anyone have any idea what could be causing this? The engine is very rough at idle and I can feel the misfire when starting up until revs hit about 2500 rpm and then again while driving at around 40 mph. I checked the plug and wire on all cylinders and they're fine, save for a little gunk, but nothing peculiar.

So what do you think guys? Any way of deducing this? I'm currently working my way through college, so keeping this fix cheap is a priority. Thanks!

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Also, the truck has 117,xxx miles with no history of problems since I've owned it.

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Pulled the #4 wire while idling as well, had no change in idle.

Swarley · #2 03-16-2014, 04:13 AM

Are any of your wires flip-flopped? I only ask because mine were for over a year. It didn't start to run rough until the last few months.
Bought it from the stealership that way.

MyNameIsAaron · #3 03-16-2014, 04:41 PM

Quote:

Originally Posted by Swarley

Are any of your wires flip-flopped? I only ask because mine were for over a year. It didn't start to run rough until the last few months.
Bought it from the stealership that way.

By flip-flopped do you mean hooked up to the wrong cylinder?
I checked them and they're all good.

Drove to work this morning, she was still riding rough and backfiring like a mother, only the P0304 code was present. Got home a minute ago, checked codes again and now its throwing the original P0304, plus a P0174 (System too lean - Bank 2).

Before cleaning the MAF sensor it was throwing both lean codes, now just the one... I'm a little confused lol I tried checking for vacuum leaks but the weather here got pretty crappy pretty fast, so I guess I'll have to wait a day or two to get any real checking done.

Ranger_Lui · #4 03-16-2014, 06:05 PM

My cylinder 5 was misfiring and it turned out to be a bad fuel injector.

reconjb · #5 03-16-2014, 06:25 PM

have you pulled the plug in cyl 4 to see what it looks like it can often times tell you a lot

MyNameIsAaron · #6 03-16-2014, 10:18 PM

Quote:

Originally Posted by reconjb

have you pulled the plug in cyl 4 to see what it looks like it can often times tell you a lot

I have not done that, maybe that'll be the next step in this process of deduction lol

I just don't understand how cleaning a sensor on the CAI could cause it to misfire... I mean, I didn't remove or change anything other than the MAF. I unplugged the battery, unplugged the sensor, and cleaned it following instructions.... Wtf did I do wrong? lol

MyNameIsAaron · #7 03-26-2014, 10:49 PM

Well reconjb, thanks for your advice! I pulled the plug from #4 and look what I found! What's scary is that I was able to unscrew it with my fingers and just pull it out. I swear, if I ever run into the P.O. I'm gonna kill him. It's just been one thing after another with this truck (which I love), which was all caused by improper maintenance or repair. Hell, I even changed the oil this weekend and found that the filter was cross threaded! Talk about a bitch to remove...

Anyway, the plugs didn't look that bad at all, but I'm a big believer in if you're changing one then might as well change them all. Plus it gave me something to do... So new plugs and wires all around! Took about 1.5 hours, which I don't think is too terrible for my first ever plug and wire change. I didn't have to remove the tires or anything, and I was able to make due with just a 5" extension, a U-joint, and my actual 5/8" plug socket. Now I just need to find something else to fix!