My 460 (Under)Powered 1996 F350 4x4 Regular Cab Long Bed is severly lacking in the power department. It use to run really well back in the day and always made my buddy in his 360 powered '96 Ram 1500 look like he was sitting still when we raced. I know my engine is a 460 and his a 360 but at 1200lbs. heavier my truck always made short work of his. I have 285/75/16's and he has smaller 245/75/16's which takes away power from me as well. We both have 3.54 gearing. Anyway, back to the topic.
The truck really started to feel like it was lugging and with only 80,000 miles on it, that seemed too soon to feel worn out. I later discovered that both rear brakes were dragging evenly so it never pulled to one side more than the other, it just felt sluggish.
Fast forward to today. I have long since adjusted the brakes but for the last 2 years it has still struggled. All the tires spin freely but I have to almost floor it in second gear to really take off fast in 2nd gear and the tires won't even spin. Not that I care about burnouts and such but when towing or hauling I feel like I'm better off using my wife's 3.0L V6 Escape. This is no joke. The truck stuggles to pull an empty utility trailer weighing about 1000lbs. up a 7% grade. On this local hill that is about 1/4 Mile long and the speed limit leading up to it is 45mph(going about 50mph before climbing)I have to shift down to 4th halfway up, by the time I'm almost at the top I'll have to shift down to 3rd. At the top I'm doing only about 35mph. Empty I can barely make it to the top in 5th gear.
I swapped in a ZF5 hoping to help free up some power over the C6 that was in it when I bought it but it was really no help.
It has headers and a gutted cat so there are no exhaust restrictions. The check engine light is not on and O2 sensors are not that old. It has an annoying exhaust tick at the headers and the only thing I can think of is maybe it's losing exhaust there and therefor the O2 sensor is not reading the proper amount of O2 and messing with the computer? If that were the case wouldn't the check engine light be on? Besides that, there was a bit of an exhaust tick back when it had stock exhaust manifolds back in the day and it felt plenty peppy.
The truck is a '96 but it doesn't have OBDII because it was made in '95 for the '96 model year. It doesn't have an MAF sensors either.
The only thing I can think of checking is removing the spout connector and checking the timing. Maybe I'll adjust it and see if that helps. I'll also do a compression test to see if maybe I've got a weak cylinder or two.
Any other suggestions would be welcome at this point.

 

The main things to check are fuel pressure and for codes, you should see 40psi at the rail within a couple primes of the pump(engine not started), 32-35psi engine idling, and pressure should always rise towards 40psi when the throttle is snapped open quickly or when under load and should never drop.
Codes can be set without the check engine light.
And you need to fix the exhaust leak, there can't be any leaks in the exhaust upstream of the O2 sensor.

 

I put a new gas tank, fuel pump, and fuel filter on the truck only about 2000 miles ago. I did this when I swapped in the ZF5.
My 460 is EEC-IV OBDI and I've never checked one for codes before.
Do you know a link for checking codes on a OBDI 460?
As for the exhaust leak, I tried fixing it. When I bought the truck it had an exhaust tick from the passenger manifold but I swapped those for headers. I used Felpro gaskets but the tick was still there and I could see where the exhaust was leaking at the block. I then tried Mr. Gasket UltraSeal exhaust gaskets and they worked for about 2 weeks before the tick came back. I spent a lot of time researching gaskets to make the tick go away and ended up using Remflex gaskets and they were good for about a month before the tick came back.
The tick was there with manifolds, it is there with headers, it eats gaskets, it has taken on a life of it's own; it can't be stopped!
It has always had the exhaust leak since the day I bought it like 15 years ago but only for the last couple years has it been gutless. The exhaust leak is more annoying than anything. The lack of power is my major concern. What good is having a 460 if the only thing it does is get 6-9MPG without the power that makes owning a 460 worth while?

 

This may be a long shot. But are you sure you are opening the throttle all the way? In other words......could something in the linkage slipped preventing you from throttling fully?

It may be worth pulling the air intake ducts, have someone else inside the truck push the accelerator to the floor and watch the butterflies in the throttle body and make sure they are in fact opening fully.

Just a thought.

 

Warm up the engine then do this:

How To Run A Self Test

 

Oh yeah, it opens to full throttle. I've had the intake hoses off and inspected the throttle body, linkage, emission hoses, etc. but it still just doesn't want to get up and go. I can rev it to the moon while it's sitting still and it sounds healthy to boot. It just doesn't want to move any weight without being sluggish; including it's own weight.

 

I'm surprised that the Remflex gaskets gave out. I installed them and checked the torque after 6 months and they were plenty tight still. My guess on the leak is that a head is warped on the exhaust port or your header is warped. what is the thickness of the flange on the header?

 

The header flange is 3/8" but I don't think the flange is the problem, I'm leaning more towards the head itself. I've pondered this for quite some time and my guess is that the previous owner let the exhaust manifold leak for so long that it warped the head where the leak was exiting. That is probably why no matter what manifold, header, or gasket I use it just keeps burning them out.
Does anyone have a clue how much a machine shop will charge to resurface the exhaust port side of a cylinder head? I'd ask one if they weren't all closed right now.
Even if I fix the exhaust leak, that won't change the lack of power since I've always had the exhaust leak but only in the last couple years has it really lacked in power. Some days are better than others. Once in a while it will really get up and go while others it feels like I'm driving a GEO Metro.

 

I scanned the trucks computer and not one single code came up. I even double and triple checked it to be sure; still nothing.
I don't know what could be causing my engine to be lugging so bad. I jacked the rear tires off the ground and ran it to get the tires spinning to see and hear if the brakes are dragging but everything is fine. The rear LSD is working fine as well I might add.
A while back I was thinking I had a dead cylinder or two but all the header primary tubes were hot and all were close in temperature.
Does anyone have a clue what could be causing the engine to be down on power?

For the record, stats are as follows:
-1996 F350 4x4 Regular Cab, Long Bed (actually a '95 but sold as the
'96 model year so it's OBD1 and does not have a MAF sensor)
-'95 460 7.5L V8 (90,000 miles)
-ZF S5-42 5-speed transmission, swapped from '93 F350 (78,000 miles)
-New clutch and clutch related items (about 2000 miles on them)
-Borg-Warner 4407 transfer case (same miles as engine)
-3.55 axle gear ratios
-Long tube headers
-Gutted Catalytic converter (O2 sensor is before CAT so no thrown codes)
-Y-pipe after cat. converter, dual pipes exit our rear with resonator tips
-New O2 sensor
-New gas tank, fuel pump, fuel filter

The O2 sensor is rather new but maybe it's slowly dying? I have noticed a lot of soot coming out the tailpipe. I've owned another EFI 460 with no Cat. Converter and it wasn't hardly sooty at all out the tailpipe.

 

From that statement above I read it to imply you did not get a System Clear Code of 111 for KOEO/CM and/or KOER?

If this is the case your Code check is invalid. You may need to clean the contacts on the data link connector. If you still cannot get any codes then you may have a bad connection to the PCM or a bad PCM.

 

It did say 111 but didn't throw any code saying something was not functioning properly. I was assuming anyone reading would know that I meant no code other than the code saying everything was OK. Sorry for the confusion.
I'm still baffled by the lack of power since everything checked out OK, mileage is rather low, and the throttle body is clean. I've ran injector cleaner with every full tank but I really don't think it would help that much. From the factory this engine is suppose to have around 245HP and 425lb.ft. of torque but it honestly feels like about 100HP and 125TQ.
I've driven other EFI 460 powered trucks that would tow a loaded 15,000lb. 5th-wheel like it was nothing while mine stuggles to move it's own weight.

 

That is exactly why we ask. If you did not get any codes then you may have a serious problem with the PCM.

 

Yes, I may. That has crossed my mind and I hope that is not the case. Does anyone have any other clue why it's down on power before I go swapping computers?

 

Anyone?.....anyone?......Bueller?

 

Have you checked ignition timing? Factory base setting is 10deg before TDC with the spout plug removed to disable computer advance but you should be able to add 2-4 deg more.

And you still need to check fuel pressure.. doesn't matter how new the pumps are some of the aftermarket pumps only last a year and others only weeks.