Engine bucking or********

Tiny
BRACEB
  • MEMBER
  • 2004 MERCURY MOUNTAINEER
  • V8
  • AWD
  • AUTOMATIC
  • 97,000 MILES
No repairs have ever been made to this vehicle to my knowlege. It has 97,000 on 40,000 of which I have put on it.I recently changed the oil. About 100 miles ago. Today while driving my engine started bucking when I hit 50mph stopped when I slowed, but started again when I picked up speed.I was on the highway and was about 5 miles from so continued driving then an engine override light came on. What is happening. It runs and Idles(has a slight surge when Idling)
Wednesday, January 12th, 2011 AT 1:35 AM

3 Replies

Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
Scan the engine for codes and bring back to me
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Wednesday, January 12th, 2011 AT 7:24 PM
Tiny
BRACEB
  • MEMBER
  • 4 POSTS
I had the vehicle scanned at auto zone. No codes came up.I filled my tank put in a can of heet seem to run fine. Gotgas mileage has gone down from 18 to 12 mpg. It stalled out once at a stop light. It did start again.I was able to get home. The engine surges slightly at idle about 50 rpm when idling. Could my fuel pump be going?
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Sunday, January 16th, 2011 AT 5:04 AM
Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
It could be, but you need to check fuel pressure, and I would also check the iac. And clean out the throttle body, I think the iac may be eratically, and one more thing, the mass airflow sensor, may be faulty or just need cleaning.(There is a special spray for that.
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Sunday, January 16th, 2011 AT 3:00 PM

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