Intermittent Miss/Backfire

Discussion in '6.0L PowerStroke Engine & Drivetrain' started by Skylor622, Aug 4, 2020.

  1. Skylor622

    Skylor622 SDD Junior Member

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    Mar 30, 2020
    I want to apologize in advance for what feels like a super long post as I was writing it.

    Alright to start off I will give a run down of the truck to the best of my knowledge. I am by no means an expert on diesels or any one thing in particular but I am not engine/vehicle illiterate. I also did not build this truck so anything mentioned or aftermarket is either hearsay from previous owner or unknown to me. The truck is a Feb of 2003 built F350. It has the ZF6 transmission. The engine, which I was told was replaced with a junkyard engine is also tagged as an 03 model year. The engine has supposedly been studded, and EGR is deleted. It has an S&B intake, and what I was told to be an "aftermarket compressor wheel" which I am assuming is something along the lines of a wicked wheel but I dont remember being told that specifically. It also has a full 5in MBRP straight exhaust no cat no muffler. It has an Aeromotive A1000 lift pump with aftermarket regulator and the secondary fuel bowl has been blocked off. From what I can tell unless aeromotive has changed their design over the years it looks to be a "homemade" setup and not a kit that you would normally find from Aeromotive/FASS/Airdog. I was told that it has Warren Diesel injectors but I was not informed on the details of what specific injectors they are which in some cases poses a problem to me. Unrelated to the situation I was told it had a Southbend stage 2 clutch. The truck is run by an SCT tuner on Warren Diesel Injection tunes. Any other info needed that I may have left out on accident please ask and I will do my best to find the answer or look. I apologive if I left anything pertinent out.

    Now some backstory and the problems...

    I Purchased this truck about 2 years ago with no known issues other than transmisson related issues that I was willing to deal with. The truck ran good when test drove and purchased. Somewhere along the way that I cannot seem to reference, it developed a slight miss when cold that would go away once warmed up to operating temperature. I dismissed this maybe maybe to my demise. About a month ago now the truck shut off on me and left me stranded along side the road. I found the problem to be a burnt power wire to my lift pump coming from the relay. The relay when installed was never secured and I assumed the wiring had got against the brake master cylinder and had arced causing this issue but Im not ruling it out to be unrelated. So I fixed the wiring issue and drove it home now problem. At this point I realized that I had not changed the oil in this truck or fuel filters since I had bought it, mostly due to the fact that up until recently this truck had never been my daily driver and rarely used unless I was towing or hauling something. So I had not put a lot of miles or hours on the truck. I Replaced the Fuel filters both in the stock pump housing (Motorcraft) and also on the lift pump setup (Caterpillar). I replaced the oil filter (motorcraft) and found that it had previously had a Wix? possibly filter installed that was made into the filter cap. I had to purchase a cheap aftermarket (Advance Auto) oil filter cap in order to use the motorcraft filter and get the truck back on the road. The truck was filled with Rotella T6 15w40 and hot shots stiction eliminator. I primed the fuel system per recommendations read online cycle key three times for 30 seconds before I attempted to start the truck. All said and done the truck was running better than ever. I drove it for a few weeks at this point being my DD without issue, not even when cold. I had been running the truck on the WDI race tune, because I had been told by previous owner that it got better fuel economy suprisingly while on it, although I can personally say I noticed a ton of difference between it and the street tune economy wise. I do not beat on nor abuse the truck but I do not necessarily baby it either. So I filled the tank at the same fuel station that I do on a pretty regular basis. I returned the truck to the street tune in order to compare Mileage now that the oil and fuel filters had been changed to see if their were any difference since this routine maintenance. Shortly after, my miss returned. Basically the truck under normal cruising conditions "bucks/stutters. It seems to clear up under WOT about half of the time. the other half of the time it will still get up and go but you can notice a notable change in exhaust note. It just doesnt seem to have the "bark" that this normally has. and in some instances still breaks up/misses. As another symptom I have also noticed on occasion that the truck will backfire out of the exhaust. It will do it either on a shift or will do it while sittin idling. When it backfires on an idle it will throw a puff of black smoke. The truck obviously being tuned bit and not stock does smoke but so far through everything nothing that I would necessarily call excessive.

    What Ive done so far (Not much)

    So I have pulled all of the injector plugs and checked the harness's and have not found anything wore threw/burnt etc.

    I pulled the intercooler piping from the cold side and realigned/inspected the silicone couplings for boost leaks. Only because of the way they looked on the piping not necessarily because I thought it was related. I did not find any excess oil inside of the turbo housing or the piping. I did however find that my turbo does have a very small (1/16"-1/8" Maybe?) amount of up and down shaft play. No in and out shaft play. This obviously will need addressed but not sure if related?

    I have drained both fuel/water seperators and found nothing abnormal, in hopes of bad fuel. I am about halfway through my second tank since this started.

    I have pulled the ICP Sensor plug to see if that was the culprit to no avail. I tried this both on the race tune and street tune. truck would not run and will not run correctly reverted back to stock tuning.

    I do not have the capabilities or the special IPR (trick?) harness in order to check for HPO leaks. at this point I am assuming one of three things. The IPR, Bad injector/s, HPO leak.

    Now for some numbers. I dont have any cold numbers only hot that I took today on my way home from work. All number come from the SCT tuner


    IPR duty cycle: .25

    ICP: 1200psi


    Injection Pulse Width:1.12

    EGTs were around 450F













    On an end note my FICM normally sees 47.50-48v and has started to occasionally drop to 47 but never lower. it does not drop when starting. and my batter see a normal 12ish volts KOEO 13ish at start and 13.5-14 once the alternator starts to charge. Im trying to be as transparent and infomative as possible while trying to remember everything that I possibly can that would pertain to this issue. I am sorry if I have forgot anything especially something simple. If any further info is needed ask and I will do my best to get the information. Im trying to not spend a pile of money right now with work being slowed down due to all that is going on so I do not want to just start throwing parts at it. OH and the Tuner and also a generica code reader does not shown ANY codes whatsoever not a misfire, nothing. But the tuner did throw a code for low ICP sensor voltage when I unplugged it to check and see if that was possibly the issue. Thanks in advance for any help it is much appreciated!!!! This is my only vehicle for the time being and my DD to and from work. I also will be posting on multiple forums just so the guys that are members of multiple forums have a heads up and dont reread the same post a million times.
  2. troutwest66

    troutwest66 6.0- The Dark Side!

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    Apr 5, 2005
    Post Falls, Idaho
    The first thing with the 6.0 is it has to be scanned with the proper Ford software or one that reads CAN language. My diesel shop has the the correct software for all of that. Might be cheaper to have a good shop start there than buying it yourself.Sounds like you're pretty good digging into it so for you getting the correct scanning tools might be worth it. Start there. I did have some rough running with 3-4 bad injectors with mine the first year I had mine. Evidence of poor maintenance by some previous owner with water corrosion on the injectors. I had a sooted up EGR in the beginning (now gone) and turbo that didn't help either afterwards. There are so many sensors now that scanning is the smart starting point. The tuning could possibly be the problem, too. Although the SCT tunes are supposedly the best for the 6.0. Good luck.
    Last edited: Aug 13, 2020

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