I have a 92 F150extcab 4x4 with a 351 and auto trans with OD. When I drive for over an hour on the express way my truck chugs and pings when going up slight hills. This happen at speeds over 65mph and about 2000-2500rpm. I thought it was a tranny problem so I flushed the trans with no luck. Any one have any suggestions!

 

Try the easy, cheap things first.

It could be bad gas - try changing brands and increasing the octane.

Is your cooling system working well? A hot engine will ping easier than one that is at normal temp.

A tune up might help - make sure the spark timing is right and not too advanced. New spark plugs might help.

I think the OD on your trans is very tall- you may be better off down shifting into drive. A heavy load on the engine (lots of wind resistance in addition to the hill) and low revs are the perfect combination for pinging.

[This message has been edited by dirt bike dave (edited 02-13-2000).]

 

Could be a bad or partially plugged fuel filter making it run lean under heavy load

 

Fuel filter might be a starting point. Was having a similar problem with my '85 Honda Accord beater car here recently. Replaced both fuel filters (this particular Honda uses a primary and secondary) and thought I'd inspect them both. When I poured the fuel out of the primary, on the inlet side I poured out what looked like a big booger! No kidding, it was a big thick red bunch of sludge. Car runs like a top now. I'd also check your spark plugs, make sure they're the correct plug and gapped correctly and check the timing, too.

 

I had same problem in a 73 Bronco I had. Felt like i was running out of gas on the freeway. Couldn't figure it out. Removed the fuel filter, turned it over and shook it out over my hand. Little chunks of rust came out, turns out my gas tank was rusting out bad. Put new filter in and was fine.

Bones

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2000 F-150, XLT, 4X2, Ext. Cab, S/B, 4.6L, 3.55 L/S, Tow Package, Premium Sound CD Player.

Future Mods: NONE, I'm broke.

 

I going to put it on the scope and check out your suggestion friday, I'll let you know what I find. Thanks for the replies!