2006 XLT 3.0 w/140k, always been a superb runner.

Then while idle was normal, after driving away at higher revs engine has no power, like it's on 4 or 5 cylinders... and the CEL was flashing, then steady, then flashing, goes back and forth. Idle sometimes a little rough. Will occasionally 'catch' and have full power again.

I believe it still has the orig plugs/wires, so today I pulled 1,4,5,6 (couldn't get the other two wires off). #1 looked lean, other 3 ok but really worn. As a test I set the gaps back to .058 (were .100ish!) and put them back in. Also disc the battery to clear the CEL.

Now it has a rough idle, and at low speed cruise it stumbles. If I'm on the gas at all it's fine. No more CEL. But consistently poor idle.

So, seems like ignition since I fooled with the plugs and things changed. I should get new plugs and wires? And maybe coil pack if that doesn't do it?

Appreciate any advice, while I understand engines I haven't ever had to do any work on this one. TIA!

The first thing I’m thinking is spark advance (older distributor systems) as the spark timing is advanced under acceleration but “normal” when cruising or at idle. On a DIS system of course you can’t just twist the distributor and correct the problem. I suggest checking the timing, based on what you describe. Having said that, perhaps some more experienced members may have other ideas; I’ve only recently gotten back to older Fords after a 12-year break.

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2000 Supercab 3.0 auto RWD

Previous:
2002 Explorer 4.6 Eddie Bauer 4x4
1999 Ranger Supercab 3.0 5-spd RWD
1986 Ranger 2.9 RWD

You have 140,000 miles on a set of spark plugs and wires.... how about spending 40 bucks on a well overdue tuneup and check back with us.

ummmmmm do a tuneup on it! then report back......

Oops, was reading too fast, skipped over the part where he PUT THEM BACK IN!!!

SMH. Carry on OP

__________________
2000 Supercab 3.0 auto RWD

Previous:
2002 Explorer 4.6 Eddie Bauer 4x4
1999 Ranger Supercab 3.0 5-spd RWD
1986 Ranger 2.9 RWD

Yeah, yeah, I know... I put them back in because I ordered a new set, but wanted to see what would change if I got the gaps back into normal range while I waited.

Had it out last night, would miss and bog and 20mph max, then clear and run fine for a short period. Got my CEL back on again too.

Will report after new plugs/wires, thanks.

new plugs wires.. clean your throttle body and MAF sensor... prob run like new!

Had some time, here's where its at: I put in new plugs, cleaned MAF (well, I sprayed it, didn't look much different). New air filter. Wires are still old ones.

Mildly rough at idle, smooth while accelerating and while warming up, but *after warming up* will run smooth on the highway and then suddenly run rough and start flashing the CEL, then run smooth again.

So what is the DTC associated with the CEL?

Went to Autozone and read the codes: P0303 and P0316.

I closely inspected the wire for #3, there was a small discolored spot and a matching spot on the valve cover. I physically separated them, no change.

I also went to make sure the cap was pressed all the way onto the plug, and darn if I didn't feel a little "clicking" feeling, like a metal piece inside the wire end is broken. Pressed on other plug wires, they don't do that. So I 'm waiting for it to cool down a little and I'll pull that wire and ohm it out.

#3 wire seems fine, no different than the others, ohms out fine. Put it back.

I also 'touched' the hose that comes off the driver-side front of the engine, labeled "Vapor/Vent", just wiggled a little but didn't really move it. I think this is the hose to the EVAP Purge Valve?

Truck now runs fairly good, occasional roughness while driving, and a little rough at idle but not too bad. A little rough under light throttle at 1800 RPM, turn the OD off and it's smooth at 2200. I've driven a bit local and highway, and the CEL has not come back yet.

Recommendations? I'm still going to replace the wires just because. With the way the symptoms vary I'm starting to think it's not valve recession. Maybe one of the acronym parts? (e.g. PCV, EVAP, XYZ, ???)

Ok, now with new plugs and wires there is still roughness, but it is more consistent.

Rough idle, and rough while cruising at light throttle under 2k rpm. By rough I mean I can feel it and I can see the hood bouncing. No CEL tho.

Give it a little throttle, or cruise over 2k rpm, and it runs pretty smooth.

Ideas? TIA

Have you tested the spark on #3?

compression test time!

Replaced coil pack, now runs fine. Didn't think that could still be bad without throwing codes, but there ya go. Thanks to all.