1999 Ford F-150 Random studdering problem

Tiny
BUBBA1993
  • MEMBER
  • 1999 FORD F-150
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
When driving at operating temperature cruising about 1500 rpm to 2000 rpm it seems like a miss fire but no codes a used a snap on solous scanner when the engine is stubbling the scanner shows miss fires across the board but cannot specify the problem I have tried the dpfe, cam sensor crank sensor maf sensor a fuel filter and a fuel injection service even ran a full tank of 93 nonethonal with no luck I was told that maybe the timing chain has stretched or a failing coil pack any ideas of what it could be?
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Wednesday, March 25th, 2015 AT 6:24 AM

8 Replies

Tiny
HMAC300
  • EXPERT
Check fuel pressure with a gauge and check for a vacuum leak auto parts rent gauge
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Wednesday, March 25th, 2015 AT 7:11 AM
Tiny
BUBBA1993
  • MEMBER
I checked for vacuum leak by spraying carb cleaner around all the vacuum house and lines with no leak present and gonna check the fuel pressure when I get back to work
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Wednesday, March 25th, 2015 AT 8:55 AM
Tiny
BUBBA1993
  • MEMBER
Ok the pressure was perfect with the specs from all data my truck is the w vin could it be possible the cool packs is only shorting out at those rpm range?
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Wednesday, March 25th, 2015 AT 9:59 PM
Tiny
HMAC300
  • EXPERT
Have a pro dignose this it will be cheaper in the long run. These are extremely hard to diagnose as it can be any sensor acting up or an air leak like grommets causing a vacuum leak.
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Thursday, March 26th, 2015 AT 5:55 AM
Tiny
BUBBA1993
  • MEMBER
A ford master tech and a shop master tech two other techs and no engine code has all of us baffled
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Thursday, March 26th, 2015 AT 12:56 PM
Tiny
HMAC300
  • EXPERT
What was fuel pressure and then check compression. Also have a tech drive it with scanner plugged in and freeze frame when it happens it may be a maf sensor problem or maybe egr or dpfe sensor screwing up with low vacuum. Check vacuum at idle on intake if possible if 15" or below suspect clogged converter/exhaust.
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Thursday, March 26th, 2015 AT 1:17 PM
Tiny
BUBBA1993
  • MEMBER
All ready done the compression test all were fine did a leak down test and all test was normal drove it with the scanner and froze it checked on all data and all sensors seem to be reading just fine
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Saturday, March 28th, 2015 AT 3:59 PM
Tiny
HMAC300
  • EXPERT
No idea what to tell you without looking at it myself then.
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Saturday, March 28th, 2015 AT 4:20 PM

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