302 engine mis-firing
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Senior User
Joined: Jun 1999
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From: Nova Scotia
302 engine mis-firing
My '83 F100 with 302 would miss slightly at speeds between 50mph and 65mph. Had me puzzled for a while when I realized the miss wasn't dependant on the speed but the RPM. I don't have a tach but it seems to miss slightly at a certain RPM. I could feel the vibration in the steering wheel and gas pedal. Just seemed to happen in a certain RPM range. It also happened at times when moving from a standing start.
Today, I checked to make sure the wires were all on tight and found the coil wire not on as tight as it shold be. I also took the dist. cap off and found a large build up of corosion on the terminals. It was a white powdery stuff that I cleaned off with a little sand paper.
Truck worked great after that... miss seems to have disappeared... don't know if it was the coil wire or corosion on the terminals?
Comments?
Today, I checked to make sure the wires were all on tight and found the coil wire not on as tight as it shold be. I also took the dist. cap off and found a large build up of corosion on the terminals. It was a white powdery stuff that I cleaned off with a little sand paper.
Truck worked great after that... miss seems to have disappeared... don't know if it was the coil wire or corosion on the terminals?
Comments?
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Joined: Jan 2001
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From: Virginia
302 engine mis-firing
It would be a good idea to put a new cap, rotor, and sparkplugs in it if you haven't done so recently. If the wires physically look ok, then they probably are, but if they are cracked open and in lousy shape, you could replace them too. The high voltage tends to erroded the rotor arm, dist terminals, and the sparkplugs. High voltage likes to jump from sharp edges. The rotor tip will get rounded as well as the sparkplug electrodes.
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Senior User
Joined: Jun 1999
Posts: 303
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From: Nova Scotia
302 engine mis-firing
I thought all was OK but there is still a miss... not bad but it is there. Don't remeber when I replaced the plugs last so it sounds like a good idea to change them. Wires were replaced last summer. The rotor and cap will be replaced also since I don't know when they were replaced last either.
Thanks
Thanks
Senior User
Joined: Apr 2003
Posts: 159
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From: nowhere town nj
302 engine mis-firing
the vibration you feel when its missing, is it similar to that of a bad drive shaft U-joint. because my truck whish is not not lookign to good had a vibration/hesitation in a certain rpm range. i misdiagnosed it as transmission. though i never fixed it because the truck had another problem iw ould liek to know a little more about it, ill have to fix it one day.
New User
Joined: Dec 2001
Posts: 6
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From: Hobbs, America
302 engine mis-firing
Hi all,
My 1988 F-150 (300 L6) has the same problem. I started by replacing the dist. cap, rotor, plugs, and wires, but that did not solve the problem. Do you have any other ideas? A friend of mine suggested EGR valve / sensor, but I replaced those as well, and still the problem continues. Thanks for any help.
My 1988 F-150 (300 L6) has the same problem. I started by replacing the dist. cap, rotor, plugs, and wires, but that did not solve the problem. Do you have any other ideas? A friend of mine suggested EGR valve / sensor, but I replaced those as well, and still the problem continues. Thanks for any help.
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Senior User
Joined: Jun 1999
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From: Nova Scotia
302 engine mis-firing
Well, I have an update... I had the u-joints rechecked and they were OK. There were no wieghts missing off the drive shaft.
Before I started replacing ignition parts I did clean uo the contacts in the distributor and rotor and that helped a bit. Next, I rotated the tires and the vibration stopped in the steering wheel and began in the seat... but still was felt in the gas pedal. That was my first clue that it may not be an ignition problem. I had the front wheels (now rear wheels) balanced a at the local Canadian Tire Store (a Canadian equivalent to Western Auto or Auto Zone).
So this past Saturday, I stopped at Scotia Tire a local tire specialist and had them check the tires right off the truck. The tires that were supposed to have been balanced were not... by a long shot. They re-balanced them and away I went... no vibration in the seat or gas pedal. Just that easy.
Before I started replacing ignition parts I did clean uo the contacts in the distributor and rotor and that helped a bit. Next, I rotated the tires and the vibration stopped in the steering wheel and began in the seat... but still was felt in the gas pedal. That was my first clue that it may not be an ignition problem. I had the front wheels (now rear wheels) balanced a at the local Canadian Tire Store (a Canadian equivalent to Western Auto or Auto Zone).
So this past Saturday, I stopped at Scotia Tire a local tire specialist and had them check the tires right off the truck. The tires that were supposed to have been balanced were not... by a long shot. They re-balanced them and away I went... no vibration in the seat or gas pedal. Just that easy.
