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04' 4.2L V6 sputters with acceleration when warm

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04' 4.2L V6 sputters with acceleration when warm

 
  #1  
Old 09-12-2015, 01:27 PM
tntjacobs
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04' 4.2L V6 sputters with acceleration when warm

First off I want to thank everyone who contributes to this site. I have been able to find most all fixes to problems and have never had to post.

2004 F-150 4.2L V6 Manual 5 speed 160,000 miles

It does have a check engine light but am afraid to drive to have codes read as I don't want to get stuck somewhere.

My problem started a week ago while driving down the highway. All of a sudden my truck jerked like it was dying. Then it would hesitate and backfire occasionally when giving it gas. It never actually dies but will bog down, cut out, and/or back fire then all of a sudden respond when giving it gas. If it sits it will start fine and run excellent until it warms up then same thing. Last year I had a problem with it dying after it would warm up and cleaned the idle air control which fixed that problem.

I have cleaned the IAC, MAF, throttle body, changed the bosch plugs that were installed 4 years ago with motocrafts, tested the MAF and IAC electronically, replaced the coil pack, changed fuel filter, checked pvc and rubber vacuum hoses and have not noticed any cracked elbows or hoses, sprayed starter fluid all around all vacuum lines without change.

I haven't replaced wires yet because they are only 4 years old and seem to be okay. I am at a loss, I have read about egr, fuel pump, and injectors but wouldn't these problems occur when cold too. I was considering changing the temp sensor thinking it may have something to do with the computer thinking it's too hot/cold.

Any suggestions appreciated.

Tyson
 
  #2  
Old 09-13-2015, 09:46 AM
tntjacobs
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So Update: Yesterday I disconnected all of the vacuum lines and plug wires from the coil, everything seemed tight, inspected all lines no cracks holes, etc. put all back together and tested fuel pressure, running at 35 KOEO, 30 KOER, 40 with FPR vacuum disconnected KOER, does not drop with snap throttle (actually bumps up a couple), let it warm up to see what fuel pressure was when having problem, never started having the problem, checked again this morning, still not having problem after running for 30 minutes (normally takes about 10 minutes).

So at this point I think

1) either something was loose, wire or vacuum line and I fixed when putting back together, or

2) it is heat related as a cold front moved through yesterday evening and it is not as warm out as it was, if it happens again I will try the CHT sensor and maybe the thermostat.
 
  #3  
Old 09-14-2015, 12:07 PM
tntjacobs
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Well, today drove around for about 45 min to an hour, filled tank up, put in fuel injector cleaner, then headed home, truck stumbled a couple of times but nothing near like it had. Cleared codes the other day when I disconnected all vacuum hoses and coil, no CEL today. I didn't have AC on until after filling up, not sure if that has something to do with it. Letting her run now, hopefully it will act up and throw a code so I can go have it read. Starting to get frustrating.
 
  #4  
Old 09-19-2015, 12:43 PM
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So finally got codes pulled, IAC, Crank shaft position sensor, and lean codes both banks. Changed IAC, and went to change Crankshaft positions sensor when I noticed the wires were bare, fixed those and fingers crossed all is doing well.
 
 
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