inline six misfiring
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New User
Joined: Jun 2007
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From: Anchorage, AK
inline six misfiring
I own a 93 f150 4.9L six cyl. EFI with 172k on it. It started misfiring recently to the point that it left me stranded at a light. Gas milage is bad, down to about 6-7 MPG. It still runs great alot of the time, but loses it after a little bit, but then it seems as though it can clear up a little later. I cant pin point the problem. I replaced the plugs, wires, cap, rotor, and coil, and fixed what vacume leak I could see. Tested the compresion in a couple cyl. and it seems good at around 120.
I am thinking that it might have a fuel delivery problem, and i also read on here that the EGR valve could cause these symptoms. How can i check to see if this has gone bad?
Any help would be appreciated.
Thanks
AJ
I am thinking that it might have a fuel delivery problem, and i also read on here that the EGR valve could cause these symptoms. How can i check to see if this has gone bad?
Any help would be appreciated.
Thanks
AJ
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New User
Joined: Jun 2007
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From: Anchorage, AK
still misfiring
I checked the egr valve by unpluging the vacuum line on it. That made little to no difference. I changed out the fuel filter. Pulled the codes and got a random code, i think it was p238, but it meant a faulty coil #4. this doesnt make sense to me. I was trying to check the timing on it, and have found out that it skips around alot. I cant get it to even hit on the measuring points.
Any ideas as to what could be wrong still.
Any ideas as to what could be wrong still.
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New User
Joined: Jun 2007
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From: Anchorage, AK
Haven't got back to this in a while. Anyone have any more ideas or sugestions on this problem. I thought i had sold her but the guy didn't pay me for months so i took it back, and want to fix it before i sell it again.
Last edited by aksnopro2; Sep 22, 2008 at 02:23 PM. Reason: spelling
Mountain Pass
Joined: Dec 2007
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Mine did sort of the same thing a while back. Would run good for a while then crap out on me. This went on for a month and never threw a code so I was stumped. Then one day check engine light flashed for a split second and I checked the codes immediately and it showed a code for a MAP sensor. I changed the MAP sensor and it has ran good since. I wouldn't change out a sensor until it throws a CEL, but you may have a sensor trying to go out on you. Did you check the codes yourself or take it somewhere?
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From: Anchorage, AK
Thanks. It hasen't thrown one in a while but it did come on and off for a while there. I just didn't get it before it shut off again. MAP sensor? Im not familiar with it. What is it?
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Sure it could be the EGR sensor?
Had a similar issue where I replaced the valve and the sensor at the same time. Still had similar issues. For giggles I put the old sensor back on and its been alright since. Guess the new one was bad.
Also as a side footnote. Check the vacume lines near the EGR line. For some reason all three lines that ran next to that had rubbed up to the EGR line and fused themselves together in one solid mass. No vacume leak. But vacume wasn't getting to where it needed to go.
Had a similar issue where I replaced the valve and the sensor at the same time. Still had similar issues. For giggles I put the old sensor back on and its been alright since. Guess the new one was bad.
Also as a side footnote. Check the vacume lines near the EGR line. For some reason all three lines that ran next to that had rubbed up to the EGR line and fused themselves together in one solid mass. No vacume leak. But vacume wasn't getting to where it needed to go.
Mountain Pass
Joined: Dec 2007
Posts: 124
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Go to www.fordfuelinjection.com to get the definition of a MAP sensor. It will also tell you how to pull codes on your own. Also you can check codes anytime because the computer stores them until you clear them. I would definitely check codes again or take it somewhere because the 238 isn't in my manual or on the website listed above. Good luck
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