460 performance cold vs. hot

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May 29, 2001 | 12:00 AM

Jeepnut

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460 performance cold vs. hot

I have a '95 F-350 4x4 crew cab, with 108k miles on the 460. I have only had the truck for a couple of months, I'm still trying to get the bugs worked out of it. I have no idea about the history of the truck, it was a repo.

The engine runs great, but I have noticed a loss in power after it warms up. When the engine is cold (not "cold", just not up to operating temp) acceleration is noticably stronger. When warm (at operating temp) the power feels noticably less.

I have done a basic tune-up (new plugs, air filter) but nothing else to the motor.

Any suggestions?

Walt

May 29, 2001 | 06:36 AM

Nathan

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460 performance cold vs. hot

If you have an auto trans, I may have an answer for you. Ive noticed that both of my trucks (with C6) seem stronger when the trans fluid is cold and thick. They both pull harder and shift firmer, giving more of a performance feel.

Just a thought

Nathan

May 29, 2001 | 02:04 PM

tmyers

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From: Everett, Wa

460 performance cold vs. hot

Another thing to check is to see if you are running to lean when hot. Your choke maybe partially closed during warm up allowing the engine to run a bit richer giving more performance.

Terry

771/2 F250 4x4 460
2001 Ranger Edge

May 29, 2001 | 10:41 PM

proud owner

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460 performance cold vs. hot

When it's hot, can you tell if it is the engine or the tranny that is being sluggish? Like, does the engine rev up, but not go anywhere, or is it just like the engine loses all responsiveness and such like that?
First, depending on what kind of fuel injection you have ( Im assuming FI due to the late model year..correct me if wrong.) it could be a couple different things.. When was the last time you checked or replaced your O2 sensor(s)? When the engine is cold, it runs in a closed circuit, on it's own little program thing. When the O2 sensors heat up, they start feeding info to the computer, and that may very well be whats causing it.
Second, it may be the actual computer itself, when it senses an open loop circuit (when it warms up, in other words)perhaps it is thinking somehting is happening that really aint happening. (worst case here...)_
Good luck!

J/.c

1965 Ford Galaxie 500 (okay, so not quite a truck)
460/C6 transplant @ 389hp/491 lb.ft.
14.29@103.8, 13-14 mpg heheheheheh

May 30, 2001 | 04:30 AM

cobrajet

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From: michigan

460 performance cold vs. hot

sorry Tmyers, these engines are fuel injected chokes went by the way side years ago.......

May 30, 2001 | 08:38 AM

Jeepnut

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460 performance cold vs. hot

Thanks fpr the replys.

Yes...of course...it's fuel inj.

I thought about the O2 sensor, but I also thought the "check engine" light would come on if something was wrong with the o2 sensor - or anything else.

A side note...This truck didn't get very good maintenance, as far as I can tell. For example, the original equipment plugs were still in it after 108k miles! (I'm 95% certain). Any other ideas will be greatly appreciated.

Walt Brodzinski
Mesa, AZ
Mesa 4-Wheelers
'95 F-350 4x4 Crew, 460, AT, 4:10 gears, Roll-a-Long package

And some Jeeps

May 30, 2001 | 02:10 PM

lvstang

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460 performance cold vs. hot

A lean motor will run stronger up to the point of detonation so if anything the EFI may be keeping it fat or rich after warm up. have you checked the plugs after a hot run ???

The Ford EECIV will pull timing out when the motor gets hot which sounds to me like is what may be happening. If the motor is really getting hot enough for this you may need to check the cooling system hard parts; radiator, water pump, belt etc.. If it isn't running that hot check the various sensors that relay the info to the EEC. The 02's could also be sending the wrong signal when warm making the motor run rich and sluggish.