What causes a little backfire and low idle

Tiny
WATSONJ8
  • MEMBER
  • 1999 FORD EXPEDITION
  • 200,000 MILES
I changed the Head on 5.4 triton 2v. The mechanic didn't set timing correct and the vehicle wouldn't crank. Then I set the timing per the manual and it cranked. Sounded really rough and would not stay running. I have changed the starter, starter block, battery, IAC. It will crank up but is idleing low and is hesitating with some backfire. I am afraid to take it out of the driveway for the fact that I may not get it back. Anything I can do to check and see why it is hesitating
Monday, October 31st, 2011 AT 12:55 AM

8 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Your mechanic may have bent valves with setting the timing wrong.

Roy
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Monday, October 31st, 2011 AT 2:22 AM
Tiny
WATSONJ8
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  • 5 POSTS
Should I do a compression check on engine or go ahead and get take the heads off and get the valves checked?
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Monday, October 31st, 2011 AT 5:31 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
No, start with basics. A compression test is the right thing to do.

Roy
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Monday, October 31st, 2011 AT 8:41 PM
Tiny
WATSONJ8
  • MEMBER
  • 5 POSTS
If you can watch these and tell me what you think I would appreciate it. I have had three so_called mechanics come and check it out. I have gotton further myself and I am not a mechanic. One of the three acutally works for ford. Let me know, thanks. Is there an email so I can send a video? I dont think I can send it here
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Monday, October 31st, 2011 AT 9:05 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Roybelding@comcast. Net

Roy
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Monday, October 31st, 2011 AT 9:19 PM
Tiny
WATSONJ8
  • MEMBER
  • 5 POSTS
I sent you links to youtube, for some reason I could not attach them to an email. Just click the links and it will take you directly to it
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Monday, October 31st, 2011 AT 10:19 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
I think you have problems. I am afraid that one or more of the valves is bent.

Roy
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Monday, October 31st, 2011 AT 10:59 PM
Tiny
WATSONJ8
  • MEMBER
  • 5 POSTS
Just pulled the head off and low and behold, you are right. My concern is the piston head. Has small nick in each one at the same location, no cracks. Size is smaller than a eraser head, slight burr. Should I knock the burr down or smooth it out, or just leave it? Also, the cylinder location, the number one is at TDC, where could I find a side diagram of 2, 3, 4 cylinder locations when number one is at TDC? Just want to cover all my basis so I do not have to redo this again.
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Thursday, November 3rd, 2011 AT 9:58 PM

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