1998 Ford Explorer Ford 98 Explorer 5.0L auto: miss, shudde

ROCKETKNIGHT03

MEMBER
1998 FORD EXPLORER

Engine Performance problem
1998 Ford Explorer V8 Four Wheel Drive Automatic 150k miles

Did a full tune up on the customer car two weeks ago. Now, there is a miss fire on cycl 6 consistently, and a shudder in mid range. Torque converter possible, But for the CEL, "P0306" on the miss fire for 6# seems unlikely. Wire, coil packs, plugs, cam sensor, seafoam treatment. Went away with a hard memory clear. No leaks, good fuel pressure at 40psi, compression tested good at 150psi. Just at a lost of words. This weekend i'm going to dig into it for the #6 injector. I think it's the issuess since nothing else would make sense.

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,901 POSTS

Did the engine have the problem prior to the repairs?

Let me know.

Joe

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Monday, December 21st, 2020 AT 11:26 AM

ROCKETKNIGHT03

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8 POSTS

Not to my knowledge, customer states it never ran like this before.

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Monday, December 21st, 2020 AT 11:26 AM

JACOBANDNICKOLAS

MECHANIC
109,901 POSTS

Then something you replaced is no good. Try putting the old parts back on that cylender to see if the miss goes away. If it does, then it's a process of elimination. Replace one new part at a time. When the miss starts again, then that part is no good.

It sounds like you have the same luck as I do. The old parts work, and the new ones don't.

Let me know what you find.

Joe

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Monday, December 21st, 2020 AT 11:26 AM

ROCKETKNIGHT03

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8 POSTS

The original issues was a tune up for DEQ, "the CEL has been on for a long time" the customer said. The original
plug where black and deep fried. Maybe he wire possible. Any other ideas?

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Monday, December 21st, 2020 AT 11:26 AM

JACOBANDNICKOLAS

MECHANIC
109,901 POSTS

Did you reset the original code? If you did, what was it? Also, what does the plug look like if you remove it? Did you check it to make sure it is getting spark? Is it wet.

These situations are frustrating. I once had a 20 year old chev citation (of all cars) come in for a tune up. Guess what, when I opened the door, the handle broke. The fact that the car had 150K on it, was 20 years old and needed to be junked didn't matter. "I BROKE IT" Isn't life grand. Also, I have gotten bad plug wires, plugs. Many times over the years. You may have gotten a bad part. Check to make sure it is getting spark and fuel to that cylender. If it is, check compression too.

Let me know about the questions. Honestly, if you still have the old parts, I would work backwards to see where the problem came from. If it still misses with all of the old parts, then you can prove it had to miss when it came in. (Or at least try)

Let me know.

Joe