1991 Ford F-150 5.8 litre. Engine misfires. Not at any certain time. No engine light.

Tiny
FFIREHS
  • MEMBER
  • 1991 FORD F-150
  • 207,000 MILES
No certain time when the problem will occur. No certain temperature. Seems to primarily happen under load. Can happen at any speed in any gear.
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Monday, October 31st, 2011 AT 9:36 PM

2 Replies

Tiny
HMAC300
  • EXPERT
Check for vacuum leaks and fuel pressure. Assuming ignition components are in good working order.
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Monday, October 31st, 2011 AT 11:58 PM
Tiny
CJ MEDEVAC
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IMMA JEEP CJ KINDA GUY, SORTA WHAT I KNOW HOW TO DIAGNOSE AND REPAIR THE BEST. I'M 100% DIY ON ANYTHING EXCEPT FOR ALIGNMENTS AND AUTOMATIC TRANSMISSIONS. I GO TO EXTREMES TO FIX MY, MY FAMILY, AND FRIENDS VEHICLES.I DO NOT LIKE TO BE "BEAT" BY A MACHINE!

I had similar sorta issues with wife's Escape

I had input from the other fellers here also. But it all ended differently than their suggestions.

Thought I'd sling it out there, for observation anyway. Open for any questions with mine. Hope it's simpler than mine!

Went thru same deal w/ '03 Ford Escape 3.0 V-6

Repetitive, fast hesitations (stumbles), lasting 1-2 seconds, varied in how far the "sets" were apart, it was more evident climbing a incline, while slowly administering gas. Random or none on level ground. Every now and again at idle, but very seldom.

---No codes --- (cleaned 1st, and/ or replaced the following

New Plugs. Then I was told use "genuine plugs". Bah-Hum-bug, there was nothing wrong with the other new ones, I just installed!

Boots and springs

air filter

MAF

EGR

A new IAC (just for Giggles!)

Performed Mega Vacuum leak searches several times. By ear, "Stethoscoped" with a heater hose in my ear! Used carb cleaner and starter fluid. Nothing!

Fought with wife many times over situation for 2+ months. She wanted to take it to a shop (Not with my EGO!)

I really hated taking off the "Plenum" so many times to access the other 3 cylinders. So much crap to take loose, so much plastic "junk" so brittle, delicate and EZ to break!

Each part seem to fix it for a day or two.I did not mind replacing the suggested parts, as I am all for "PM" and she's got 100,000 miles on her rig.

The final cure was #3 misfiring (lucked into the correct cylinder) I was gonna swap a new coil pack down the line, till it stopped

#3 was the ticket!

I had tried to get the Technical school to ride me with their portable machine---things did not work out, with their schedule.

I went to a salvage yard to get a used pack ($10) to swap around, then buy a new one if solved the problem.

So happened, the salvage yard guy had a machine, in a stored code, it said #3 had misfired. My little scanner could not tell me that!

Runs perfect now, with the New $79 Coil Pack!

Twasn't hard to remove the plenum, just time consuming.I was tired of doing it

My initial coil pack swapping plan was to swap 4-6, one at a time, allow 1 day for each to act up, swap sooner if it still skipped

Then if it still did it, take Mr. Plenum off one last time. Swap 4-6 coil packs with 1-3 coil packs. Replace plenum. Then once again run thru 4-6 again with swapping, until the bad coil was found. This would prevent the plenum from having to be snatched off 2 more times!

CAME UP WITH THAT PLAN ALL BY MYSELF!

GOT SOME PICS OF TAKING THE PLENUM OFF. WHOEVER FIGURED OUT HOW TO COVER UP ITEMS THAT REQUIRE SERVICING. WITH A "INTAKE" OUGHTTA BE TAKEN OUT AND BEAT!

Always stick with a Jeep CJ, You can diagnose them, as you hear 'em drive by!

PIC 1---THIS IS HOW THE ESCAPE 3.0 LOOKS W/ 1ST COVER REMOVED---4-6 PLUGS ARE ACCESSIBLE

PIC 2---"RACK OF RIBS" IS UP AND PUSHED TO THE SIDE

PIC 3---1-3 IS AT THE TOP OF THE PIC, AFTER 20-30 MINUTES OF WRESTLING WITH THIS BEAST

PIC 4---ANOTHER VIEW OF ENGINEER STUPIDITY!

PIC 5 AND 6---BETTER ENGINEERED, REAL VEHICLES!

LET ME KNOW IF THIS HELPS YOU AT ALL

The Medic
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Tuesday, November 1st, 2011 AT 2:53 AM

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