6 cyl Engine problem
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Joined: Sep 2011
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6 cyl Engine problem
Hello,
I have a '94 E250 with a 4.9L 6 that has a problem. After the engine warms up it knocks under hard acceleration (not while it is still cold). I wanted to retard the timing a little, but my manual says that the timing is controlled by the computer and can't be adjusted. It runs smooth enough under normal load, except that it randomly stumbles (briefly) while the throttle is held steady. I tried premium gas, and it reduced the degree of knocking, but it didn't stop the problem. It could be caused by a dozen different malfunctions. Any thoughts on the most likely culprit (or culprits)?
Tom C
I have a '94 E250 with a 4.9L 6 that has a problem. After the engine warms up it knocks under hard acceleration (not while it is still cold). I wanted to retard the timing a little, but my manual says that the timing is controlled by the computer and can't be adjusted. It runs smooth enough under normal load, except that it randomly stumbles (briefly) while the throttle is held steady. I tried premium gas, and it reduced the degree of knocking, but it didn't stop the problem. It could be caused by a dozen different malfunctions. Any thoughts on the most likely culprit (or culprits)?
Tom C
Last edited by tgcapizzi; Oct 24, 2011 at 11:56 PM. Reason: moved earlier question to another forum
Lead Driver
Joined: Jul 2009
Posts: 6,477
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From: Sheffield, AL
tgcapizzi,
Welcome to the forum!
I have no experience with the later model 4.9L, but recently investigated a similar problem involving a 1984 4.9L which although it has a carburetor and distributor, is computer controlled [timing & carburetor]. It, too, pinged easily after warming up. I did retard the timing [can be done with spout disconnected] and it slightly helped, but performance and gas mileage suffered. The MAP sensor was bad and was replaced. The timing was reset to factory specifications and the truck ran like new!
Welcome to the forum!
I have no experience with the later model 4.9L, but recently investigated a similar problem involving a 1984 4.9L which although it has a carburetor and distributor, is computer controlled [timing & carburetor]. It, too, pinged easily after warming up. I did retard the timing [can be done with spout disconnected] and it slightly helped, but performance and gas mileage suffered. The MAP sensor was bad and was replaced. The timing was reset to factory specifications and the truck ran like new!
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