Here it is - you press down on the gas and the beast slows down. It actually seems to bog down. The hotter it is the worse it is. Both the engine temp and weather temp have an effect.

I have seen several threads for this topic in the past, but I have never seen a recommended solution.

My 1989 460 is doing the same thing and I can not for the life of me figure it out.

Please, please, please is there a solution?

 

Check the usual... plugs, wires, timing, fuel pressure, etc. But for a quick easy check...

What happened to me with my 94 460 is that the fuel filter over time slowly clogs but doesn't really cause any noticable symptoms since it is so gradual.
But eventually the filter will clog enough to starve the engine. Usually worse in warm weather.

An easy way to check IF you have dual tanks is to switch tanks. If it stumbles hard, it is probably the filter.

The filter is an ignored maintenance item until it bites you. I think the filter is something like $12-$15 at most stores. You will probably need those funny disc shaped tools to remove it. On my 94 it is on the passenger side frame rail about mid way. Biggest pita is lack of room to work in there.

Good Luck,

Jim Henderson

 

Pull codes and see what shows. My 1993 4.6 PI did this and it was a combo of a bad EGR, throttle position and a bad coil pack. It never thru a Check engine Light but did have 2 codes.

 

Thanks for the input.

I've pulled the codes and all is fine. 11 on both KOEO and KOER.

The real problem is that there are so many TSB's for "Poor Performance" / "Lack of Power" on this vehicle that it leaves us shade tree mechanics with no real path to a solution. So, like everyone else I check what I can and logically (hopefully) eliminate what I can, and then work on the rest of the stuff.

Did you know that there is a TSB on "Poor Performance" that talks extensively about the type of gas to use. Well, I tried a higher octane fuel and they weren't kidding. It really made my 460 run bad. No power, backfiring, missing, etc.

OK, so I got the truck all warmed up and it started missing. Came back to the house and had my wife cool down the radiator with the garden hose. When it was nice and cool I took off. Ran like a scalded dog. When it warned up it started missing and lost power. Obviously a heat related problem.

New plugs and wires first thing in the AM. Probably time anyway. Then we go on from there. I'm gonna run and get a new fuel filter while I'm at it. Mine is easy to change.

Any more suggestions are always appreciated.

 

A weak or bad ingnition coil can cause this.

 

OK, so I'm up bright and early and start changing plugs and wires.

After about the third plug I just happen to look down at the fuel lines that run from under the truck to the fuel rails. They run right over the seam between the transmission and the engine.

The lower one has a place about an inch long where it is squashed almost flat. Guess what, I just had a new tranny put in about 6 months ago. Looks like they caught that fuel line between the engine and the tranny somewhere along the line. I don't know how much that is contributing to my problems but it can't be good.

To their credit they did an excellent job on the tranny, but why in the world didn't they tell me about the fuel line, or better yet, fix it. Who knows, maybe someone else in the distant past did it. Anyway, onward and upward.

Good news is I'm glad I'm changing plugs and wires. It need them.

 

Ancient thread... but seems a somewhat common problem with no clear solution... unless you get lucky.

My 1989 E350 EFI 460 (43k) had the same problem. Drove me and several mechanics nuts chasing after every recommended fix ($$$) in most of these 460 threads. Last guy I took it to found the C6 tranny wasn't kicking down into 2nd with WOT. Adjusted kickdown linkage and top end power restored. Very expensive lesson. None of the innumerable Internet forums I visited ever mentioned it could be a tranny problem. The only threads that actually had a posted "solution" (about 3 out of 12 that didn't just fade into history) centered on Cat Delete and/or in-tank fuel pump replacement.

I suggest putting checking for WOT passing gear linkage (or vacuum) near the top of your 'lack of power' checklist. Hope this might help someone in the future.

Bon chance, mon amis!

 

Heat, its vapor lock.