Cylinder 4,5,6 Misfire, Banks 1 Lean 2 Rich

93_Rarity · #1 11-23-2016, 07:43 AM

Long story short, I've been fighting a random multiple misfire the past few weeks. On a trip he started acting up, so naturally I pretended to ignore him and checked codes when I got home. Was throwing a random multiple misfire code, air temp sensor code, some EGR code, and bank 1 was lean (which I found strange, as both banks normally ran lean, not just one). Figuring those codes were causing the misfires, I cleaned the MAF, changed the air temp sensor, and fixed an emissions hose thing that was torn, and it solved those codes, but it didn't solve the random multiple misfire issue. Ok then, research.
Found a common fix is to replace the coolant temp sensor, so I did. It ran great for about thirty miles or so, then started gradually getting worse till it was back to square one. Next best thing I found was the fuel filter. Gotcha. Changed that this past weekend, and he once again ran like a top.
For about thirty miles. Then he started getting worse, like before. So I had codes run this morning, and the random multiple misfire is gone now, but it says he's got cylinders 4, 5, and 6 misfiring and that bank 1 was running lean, and bank 2 is running rich. No other codes. Also might be worth mentioning that if I sit at an idle for too long, the CEL starts flashing at me.
What else is there? Intake gaskets? Injectors? Any help would be appreciated.

Jswifto · #2 11-23-2016, 04:22 PM

Could be the gaskets, could be the head is cracked or a bunch of other things. First step should be to look at the plugs and wires then maybe a compression test might be in order.

93_Rarity · #3 11-24-2016, 01:42 AM

I forgot to mention that the plugs and coil pack were replaced about two weeks ago, and the wires seem good and were replaced back in February. I can try a compression test here in a couple days.

accorddude · #4 05-20-2018, 02:05 PM

If you have a cat converter on both banks then I would guess one is clogged. That would kill that half of the engine.

Undrstm8ed · #5 05-21-2018, 02:32 AM

Quote:

Originally Posted by 93_Rarity

So I had codes run this morning, and the random multiple misfire is gone now, but it says he's got cylinders 4, 5, and 6 misfiring and that bank 1 was running lean, and bank 2 is running rich. No other codes. Also might be worth mentioning that if I sit at an idle for too long, the CEL starts flashing at me.

First off, if your not burning all the fuel in 3 cylinders of course your going to get a rich code. That code will go away once you determine the Misfire issue.

Start here.. http://troubleshootmyvehicle.com/for...st-a-misfire-1

Arttie53 · #6 06-14-2018, 03:05 PM

I had a similar problem with my '94 4.0. After much testing and replacing of this and that the problem was that #1 cyl. had the intake valve sucked up into the head, seat and all was about 1/4" above being flush. Truck ran fine for the most part. Intermittent sluggishness, stalling, life sucked. Passed smog like a new vehicle which threw a curve to the mech. "Why does this thing pass with a dead cylinder?" Finally, it didn't pass. I pulled the head and found the problem. I was told that this is not an uncommon problem for the 4.0. I got a rebuilt head online and voila'! problem solved.

Ozzie8 · #7 06-14-2018, 04:53 PM

I have issues with my 2008 4.0. In the past 3 weeks we have changed the following; mass air sensor, idle air control valve, complete fuel pump assembly, fuel filter, plug wires plugs, we also cut open the catalytice converters and emptied them,new battery, alternator checked good,disconnected battery and reconnect,also 2 other new wires not sure what they do. drive 1/2 mile fine, falls flat on it's face, rpm's drop to 400.