So its been awhile since I have been on here, but I have a new problem I have not experienced before.

For starters my truck is a 99 F350 with the 5.4, 4.56 gears, 5star tunes, SPD y-pipe, one helicoiled cylinder and about 3 COPs which I have changed since I got the truck at 100k. The truck has 154k on it now. By my records the last COP I changed was about 25k miles ago before the gears and tunes which were put on around 135k.

I am experiencing an intermittent miss at take off and sometimes under acceleration. Most noticeable in OD between 35-40 mph. It is not missing like it had previously when the other COPs began missing. Previously I would be able to accelerate WOT and the COP would miss and I could swap a good COP between the cylinders until it was fixed. Now I think I will have to drive at least ten miles to determine if the new COP fixed the problem. But that is a lot of work and driving to discover it fixed nothing.

The truck seems to have decent power at WOT and pulls through every gear normally. My thought has been that this may be an injector going bad since its even more intermittent than the COP misses that I am accustomed to. I don't think it is a fuel pump issue, but I have not hooked up a fuel pressure gauge because I don't have one that will go as high as the rail pressure. I have however thrown a bottle of STP injector cleaner in the tank, but I am a little uncertain as to the worth of those little bottles.

Is one of my injectors going bad and how might i be able to determine which one without taking it to a shop who can scope it? I would rather pay $230 on an upgraded set of injectors (if any are better than OEM) than on a diagnostic fee with a couple of hours of labor to tell me an injector is going bad. What are ya'lls thoughts on this?

 

How old are your spark plugs?

 

Buy or borrow a code reader and pull the codes. It likely set some codes even if the CEL doesn't come on. Your local auto parts store would likely do this for free if you don't have a reader. Spark plugs are a common issue and a code reader will tell you exactly which cylinder is missing.

 

In addition, how old are the rubber boots? Did any water get down in the plug holes?

 

How old are your spark plugs?

Spark plugs were changed around 100k when the 1st COP began to miss.

In addition, how old are the rubber boots? Did any water get down in the plug holes?

I only know the age on three of the COPs I have changed since i have owned the truck each at different mileage but the oldest one I have changed has approximately 54k miles on it. The 5 COPs I have not changed all match in color and apparent age so I have always just assumed they are stock. No water should have got down into the holes since my hood does not leak and I have never wash my engine.

I will check codes as soon as I can, but the previous times my truck began to miss it did not throw any codes. That is why I think I will have to put a scope on the truck and run it to see what misses. But I don't have a program to do that.

 

Bump. Any more thoughts on this

 

Thursday taking the kids to school I drove through a pretty deep section of water. I did not think I hit it too hard but 30 minutes later I was getting a slight misfire on the Interstate in Overdrive. Just a bump here and there. By the end of the day when it was time to head for home it was much worse. Starting the engine I could detect a miss. As I drove towards home it got worse. Check Engine light came on & By the time I got it home I Had kicked the O/D off to keep the RPM's up. I was sick as a dog Friday and Saturday but today I got out & pulled the #8 Cop. Low and behold it came out wet. I pulled the boot off of it, cleaned the gunk out of the spring wire & blew air thru the tube. I then crammed a section of vacuum hose on my blower & dropped it down beside the plug. Good thing I was wearing glasses! I climbed into the engine compartment & looked into the hole & saw no arc marks. Refit the COP & she runs perfect again. be sure to grease the boot!

I have 124K on my Original COPs. I changed the plugs at 85K & the measured gap then was .085-.094. I figure it's about time to change them again. I have been resisting purchasing 8 new COPS when mine are working fine.

I checked One of the online Ford parts look up sites & my truck calls for DG-491, But none of the dealers have those in stock around here. They all have the COP listed for the 4.6L DG508.

Even if the SEL is not on you may have data stored in the CPU. Wouldn't hurt to go by a Parts store & let them scan it.

 

OK well I might need to take out the coil packs and dry anything off and regrease them. My CEL has not come on and I did put a scan tool on it and there are no codes.

 

You need to use a break out box with software to track down your misfires to locate which cyl. has problem. Codes won't show until it causes a problem bad enough to trigger codes and that won't tell you which cylinder.

 

What software is this and what breakout box? I figure that if it is affordable it would come in handy for all the fords that are in my family.

Is this something that AutoInginuity would be used for?

 

Did you look under the hood?

 

Yeah, real funny. Hopefully a 12 valve and ZF6 will get lost and find its way under my hood, but until then I will have to keep searching for my missing 5.4

 

The break out box and software is expensive that's why dealers charge the big bucks to check it out. Cost me about $100 to find bad coil due to an intermittent miss.

 

I have to assume from the photos your truck is lifted. Mine is stock 2WD on 16's

The inner fender liner does not offer adequate protection from water splashing up on the drivers side. I think they allow extra space for the steering column. That number 8 is a pain to get out, but now that I think about it, that was second time in 7 years that I have had to dry that cylinder. If you are missing at idle the injector is right beside the COP. Unplug the harness at the injectors one at a time until you find the cylinder that's dropping out.

If It's just a once in a while event it really pays to get a shop to diagnose it. Not sure if there are any advanced independents in your area.

 

Ya when i get i chance around an air compressor i am going to blow out all plug holes and re-grease all electrical connections (right now i am away from home doin that college thing). I do have some good shops around that i trust but they also get paid well for their trade, so i am going to try what i can before i take it to them.