Engine Hesitates and surges

Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Had you said something earlier about eh abs you might get a better response. The abs has the cruise control connected directly to it. As you apply the brakes it kills the cruise. So it's eiteh rgot a short in it or one of the wires are touching where they aren't supposed to an dkilling the cruise. It also connects to the trailerbrake if you have one as well as the speed sensor to the rear. If any of htosea re screwing up or the abs unit itself then your cruise isn't going to work right. Nexttiem give ALL the information you can, engine/trans 4wd or not as well as a complete detail of what is going on.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
BMILLER3316
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  • 8 POSTS
This makes so much sense, I'll check this wiring. I do have trailerbrakes also. Truck is a 93 f150 with a 351w which has the upgrade to the lighting mass air flow kit from ford. Thanks for so much
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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He is correct. Check the wiring (especially the trailer wiring) for damage. There also is a plug at the rear of the vehicle for the wiring to the trailer. Check it for damage.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
BMILLER3316
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  • 8 POSTS
Thanks

Going for test drive Sunday.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
DAVES327
  • MEMBER
  • 1 POST
  • 1993 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 18,500 MILES
Engine Mechanical problem
1993 Ford F150 V8 Four Wheel Drive Automatic 185, 00 miles

When trying to maintain a steady speed the engine speed drops and picks up again over and over. If I accelerate the miss is not noticable. I have also noticed that sometimes the oil pressure gage will drop to zero while idleing in gear after the engine is warm. If I slightly speed up the engine or take the load off by placing the trans iout of gear the pressure gage returns to normal. Thanks
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok first with the oil pressure we need to know what the actual oil pressure it. So it needs to be tested with an actual guage if possible. Otherwise you need to replace the sending unit and see if the pressure comes back to norm. Most fuel injected vehiles have a fuel pump shut off and if the oil pressure is low it may trigger this. So lets get a pressure reading first to see if the engine is just tired and needs some repair.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Let us know what you find.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
BMILLER3316
  • MEMBER
  • 8 POSTS
I sure will. I have completely unhooked all the trailer brake wiring. Thanks
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Thanks
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
BMILLER3316
  • MEMBER
  • 8 POSTS
Well it looks like the trailer brake controller is causing the up & down when on cruise. The wiring harness checks out fine also. Thanks for all the help.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
Disconnect the controler and see if that helps.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
BMILLER3316
  • MEMBER
  • 8 POSTS
That's what I did & it stopped the surging. Guess it's in the trailer brake controller.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
DEWY576
  • MEMBER
  • 3 POSTS
  • 1993 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • MANUAL
  • 160,000 MILES
Surges bucks at idle. Under load falls on its face I've changed map sincer cleaned throttle body new throttle bottle control module and sincer changed distributor and the ignition control module coil test good on the ohms please help lost all hope
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-1
Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
That makes sense. Time for a new controller.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Scan for codes and check fuel pressure with a gauge first auto parts rent gauge
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
BMILLER3316
  • MEMBER
  • 8 POSTS
I guess so, didn't think it could cause a surge problem. I could see it kicking it off totatly but didn't think it would cause a surge. Guess it did, thanks guys.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
DEWY576
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  • 3 POSTS
Thanks for the reply there's no codes after replacing what I did fuel checks out good also
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
Glad to help.
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Check for a vacuum leak and check vacuum from intake if 15" or below suspect a clogged exhaust. Also check voltage at tps should be0.34 at idle and 4.84 wide open throttle. Fuel pressure should be 30-45 psi key on only and 30-40 at idle. Using your finger is not a test to many people do that and figure it's ok
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)
Tiny
DEWY576
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  • 3 POSTS
Thank you for your help. Never had it back on the computer after I put the new parts on ended up buying 3 new BAD! Parts from orileys. Once again thanks for your help
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Wednesday, February 15th, 2017 AT 10:01 AM (Merged)

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