Hello,

I have a 2007 Ford f-150 5.4L 3v and while towing a very light trailer I got the check engine light flashing and the truck started to shake while trying to maintain speed. The vibrations will go away at higher RPMS (2400+) but any lower it will shake making it very difficult to drive. Code reader tells me that there are misfires on cylinders 3,4,7,and 8 along with random misfire codes too. changed all 8 spark plugs with no difference and changed the coils on cylinders 3 and 8 because those were initially the first ones to throw codes before the others did shortly after.

I tried unplugging both of the cam phaser actuators (VCT solonoids? they go by different names) with no change and I tried unplugging the MAF with no change as well. I checked the temperature of both of the catalytic converters when the truck gets up to temperature and they both were hot as well as the pipes after them.

The truck barely runs at idle now but still can get power as long as the RPMs are higher. I do have new cam phasers and actuators (VCTs?) but i'd like some feed back before I go ahead with that project.

Thanks,

Nik

 

When were the spark plugs changed last?

 

I changed them 2 days ago, prior to that I do not know as I just recently purchased this truck

 

I would do all ignition coils/boots and springs. See what happens. You could be experiencing multiple ignition coil failures.

 

Seems odd that they would all go at once? I changed two of them and they are still throwing misfire codes

 

Yeah, it's very unlikely that they all go at once. It'd be easier to narrow if it was on one bank. But you're having multiple misses...on both. Have you ensured that everything electrical is connected, clean, etc.?

 

 

The plugs that came out are Champion double-platinum 7989 and thats what I bought to put back in. I know the Motocraft sp-515 are OEM but they have the issue of splitting which I didn't want to deal with and it looks like the last owner didn't either.

 

Figured I might as well post exactly what codes were read so they go as follows:
1. P0303 - CYLINDER 3 MISFIRE DETECTED
2. P0300 - RANDOM MISFIRE DETECTED
3. P0304 - CYLINDER 4 MISFIRE DETECTED
4. P0300 - RANDOM MISFIRE DETECTED
5. P0303 - CYLINDER 3 MISFIRE DETECTED
6. P0304 - CYLINDER 4 MISFIRE DETECTED
7. P0307 - CYLINDER 7 MISFIRE DETECTED
8. P0308 - CYLINDER 8 MISFIRE DETECTED

 

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