4.9 misfire
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Junior User
Joined: Jan 2007
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From: Southern Md.
4.9 misfire
I have a 94 F150 w/ 4.9 auto, traveling at highway speed it has an occasional miss or stumble, it is noticeable at idle, idles smooth then just hesitates and goes back smooth. Has new plugs, distributor, wires,.
Thanks,
Thanks,
Senior User
Joined: Feb 2005
Posts: 292
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From: Akron, OH
I had the same issue, replaced plugs, wires, cap, rotor and coil and that fixed it. Sounds like the only one you haven't done is coil. Not to say that it is definatly your problem, but its worth looking at.
Elder User
Joined: Mar 2004
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From: Chippewa Falls, WI
If your coil checks ok. check all your wires especially the longer ones. In the past i have had bad ones right out of the box. A haynes manual will give you the resistance per foot of wire length.
New User
Joined: Jan 2007
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My 91 F-150, 4.9 Is Misfireing The Same. Changed Plugs, Wires, Cap, Rotor, And Even Robbed The Coil From My Other Truck With No Luck.
Only Does It For Short Periods And Goes Away.
Would A Bad Ignition Moudule On The Distributor Cause Such A Result?
Only Does It For Short Periods And Goes Away.
Would A Bad Ignition Moudule On The Distributor Cause Such A Result?
Elder User
Joined: Mar 2004
Posts: 580
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From: Chippewa Falls, WI
Modules are weard things. I have seen them cut in and out, test good on the tester but not work in the vehicle, etc.
If you have another module to swap in it might be worth a try.
Does it do it under any certain conditions? Cold, Hot, raining, rough road? Sometimes if you can find a pattern it can tell you more about what is going on.
If you have another module to swap in it might be worth a try.
Does it do it under any certain conditions? Cold, Hot, raining, rough road? Sometimes if you can find a pattern it can tell you more about what is going on.
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I may try another module, it is from a 302 distributor though. Not sure if that makes a difference or not. It allways does it when it first starts cold, just like clockwork. Then when I decelarate to a stop, the motor will sit there bucking and about die till I get into 3rd gear an it goes away like nothing happened. I would run a scan tool on it, but when ever I'm around a shop it runs perfect. -go figure Will a bad sensor store history in the ecm like an OBDII system?
Junior User
Joined: Jan 2007
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From: Ontario, Canada
I tried the higher grade of fuel....notta...it hesitates more when the engine is cold...my truck is manual shift...it scares the neighbors when i see them looking out the window and here's Jimmy boucing the front end up and down the street LOL
I guess it's a process of elimination...the wires and plugs and cap are new...i'll try the coil next. Thanks Guys
Jim
I guess it's a process of elimination...the wires and plugs and cap are new...i'll try the coil next. Thanks Guys
Jim
Senior User
Joined: Oct 2005
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From: Berlin, CT USA
Try this, KoEo but listen for the fuel regulator u should hear it click on, also check your fuel relay switch, on my 87 f150 its mouted to the air filter. When i tried to make it die i had a tester alrdy connected, jumped out tested it and got code 87 fuel relay switch. Relay is only 12$ at napa good luck
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Junior User
Joined: Jan 2007
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From: Southern Md.
I done some work on it today, routine stuff, changed valve cover gasket, O2 sensor, throttle body gasket, cleaned throttle body and air bypass valve, checked vacuum connections, didn't see any obvious causes for the intermittent miss. After work was completed I started it up and it ran smooth as silk for about a minute or two then it went back to the occasional miss. Can dirty injectors cause this ? It doesn't miss under a load it just runs along fine then has the hesitation or miss. One member mentioned the coil failing I have never seen a coil fail this way but at this point I may try one anyway.
Thanks,
Thanks,