Hey guys, comin over from the Super Duty forums, having some issues with my 2V 5.4 that nobody seems to have encountered with SD's before, hoping maybe some of you 5.4L 150 guys may be able to help me out

My engine has been misfiring like crazy, but does not throw a code. It misfires the worst when its really humid or raining. But when it does misfire it only does so periodically (usually around gear change or getting into the throttle a little bit) but then the engine corrects itself, the longest string of misfires i've ever had was maybe 45 seconds... they usually last 1 to 5 seconds.

So to try and correct the issue, I have:

-changed all 8 plugs
-bench tested all 8 coilpacks, they are all within Ford specs and within 1% difference of each other
-changed fuel filter
-cleaned MAF
-verified all engine electrical connections are good
-checked all voltages around the engine bay

When I throw a scanner on it, it does not show any pending codes. When I pulled all 8 plugs, 5 of them were snow white indicating a lean condition, and the 3 others were a tanish color looking like a well used plug.

Currently I am suspecting either a bad TPS, Cam position sensor, or crank sensor. Have any of yall experienced anything similar? Looking for any leads as I really can't afford to throw any more cash at this issue without finding the problem.

Thanks in advance!

 

Before I changed out my COPs. I bench tested them and they all passed. Replaced them and my CEL disappered.

Did you check your boots when you checked the COPs? How many miles on the OEM?

 

Roughly 160K, and I did check the boots. Believe it or not below where they meet the head, they look brand new. The nature of this problem leads me away from suspecting them, as I have no check engine lights and the problem seems to be more timing related than anything else.

 

Cop's can bench test fine sometimes and still misfire under load or acceleration and wont show any codes. It;s been seen many times. I would change them. Global automotive store on ebay sells the whole set shipped for around $100 with lifetime warranty and have good reviews.

I would also run some seafoam in the tank to clean the injectors or have them cleaned and flow tested at a shop. If you get a chance clean your IAC also. With that many miles, things get pretty gummed up.
Wouldnt hurt to pull the throttle body and elbow and clean the egr ports. Youd be surprised how restricted they can get. It's all only about an hour-2 worth of time

When was the last time your O2's were changed?

I would still guess COP's

 

Well thanks man, I have actually run lots of seafoam thru this truck, and currently have a large bottle of Lucas injector stuff in there now. I have had troubles with my IAC when the temp drops below 0F, everynow and then the truck will stall, I need to clean it out.

Other than that all sensors/ electronics are original except alternator and battery, I have a very unique way of toasting them regularly. I haven't pulled the fuel rail yet, probably should but until the Harley is back I can't be without a vehicle that long.

Also, I have never changed my O2 sensors. I always read that when they go bad the truck runs bad all the time and will run rich. Based off the plugs I removed I facing a sever lean condition which indicates the o2 is still kickin

Also, I'm not sure how the 150's are set up, but I DO NOT have a post cat 02... hence the vanishing act my cat conv. pulled. Not sure if that changes anything or not?

Also, do I need a new gasket if I pull the throttle body and clean her out?

 

Turns out these aren't misfires they're backfires thru the intake... ideas?

 

Also just found out my truck is from Miami Gardens, FL... dropped the glove box searching for PCM and found many receipts from 05 and 06 from advance auto and a tool store from there...

Is anyone on here from Miami? I really want to know WTF they did to this truck

 

Okay, so here's the run down:

8 new coil packs
8 new plugs properly gapped (this makes it 16 plugs in the last month or two)
no CEL or codes

STILL MISFIRES BELOW 1500 RPM LIKE CRAZY. So anyone got any ideas what else could be goin on? All my plugs where snow white once again, could this be a vacuum leak?

All misfires occur while the truck is running in open loop, when its in closed loop I have no misfires at all. I dont know if this is because once the engine is warm it switches to open loop or if it's temperature related. Hope someone can help.