Like Pulling a House on the Highway

Hey Everyone, I Have an 2008 XLT, 4.6 Liter, AWD with 3.55s. I was told that this thing would pull my Enclosed 6x10 with complete ease, and with it completely loaded it weighs around 2200. When I am in town I can barely tell that its even hooked up, but as soon as I hit the Highway its like I am pulling a semi trailer. I just do not get it, everything on it is new, no codes except the P1000 and it just acts like its weak as hell. Changed the in like fuel filter a few weeks ago only to find that it was filthy as all hell, never seen one this dirty, and now that it is clean again the truck runs completely different. I was excited to see if it pulled the trailer better once I changed that but it does not, its just a dog. The transmission sometimes wont shift up into the next gear after I have pulled a while and that only happens when I am getting back on the highway, I have to let off to get it to shift, but then it quits doing that again, I have been working on cars since I was in my teens but this one is killing me. Anyone have any suggestions that might change something, as I am at a loss here.

 

[Fix4Dirt]

sounds like the trans is hesitant to shift, hows the fluid look? also i assume you know this but depending on the load sometimes/usually dont tow in overdrive

 

[Lee's Automotive]

I would recommend not towing in O/D turn it off and see how it does

 

[FMSD16]

I never tow in OD, thats why I am so confused. The trans hunting is very intermittent, usually only when i jump back on the highway. Trans temp and fluid are excellent as well..

 

[Josh P]

What do you have in the trailer that it only weighs 2200?

 

[CallMeSyd]

Immediately this sounds like clogged catalytic converter. Not fully clogged, but clogged enough that you notice the loss of power when you need it most. Driving around town you wouldn't notice, but on the highway with any load you would. Wouldn't throw any codes. Anything else I can think of that would cause this would set a code.

 

[FMSD16]

What do you have in the trailer that it only weighs 2200?

Trailer is only 1500, and I race RC Dirt Oval, so all of my cars, equipment, and other stuff that I need when I travel. If I am going on a real far trip the trailer is more around the 2500 mark..

 

[FMSD16]

Immediately this sounds like clogged catalytic converter. Not fully clogged, but clogged enough that you notice the loss of power when you need it most. Driving around town you wouldn't notice, but on the highway with any load you would. Wouldn't throw any codes. Anything else I can think of that would cause this would set a code.

You really think this is what it could be, and I know replacing that is going to be super expensive. Being that I have 2 of them I couldnt just knock all the inside out to see if it helps, not to mention, they are in the worst spots you could think of. Guess i will have to price some......

 

[Mbrooks420]

You really think this is what it could be, and I know replacing that is going to be super expensive. Could I just knock it all out, or will that cause it to throw a code or sound really bad?

Don’t gut the cats, especially as a troubleshooting measure.

It’s probably also not the issue. Clogged cats would keep it from pulling off the line well, it wouldn’t just show up on the highway. Enclosed trailers catch a lot of wind. If it’s not shifting properly after towing awhile, you likely have a transmission issue.

 

[FMSD16]

Don’t gut the cats, especially as a troubleshooting measure.

It’s probably also not the issue. Clogged cats would keep it from pulling off the line well, it wouldn’t just show up on the highway. Enclosed trailers catch a lot of wind. If it’s not shifting properly after towing awhile, you likely have a transmission issue.

Yeah, gutting them is something I most likely would not do because of trying to eliminate things one by one here. It gets off the line great, runs excellent, and yeah the trailer is a Aero Nightmare, however I can pull it with ease using my wifes 07 2wd with the 4.0. Her truck makes mine look like a wimp, lol..

 

[Josh P]

Yeah, gutting them is something I most likely would not do because of trying to eliminate things one by one here. It gets off the line great, runs excellent, and yeah the trailer is a Aero Nightmare, however I can pull it with ease using my wifes 07 2wd with the 4.0. Her truck makes mine look like a wimp, lol..

Does the other vehicle have 3.73 gears?

 

[410Fortune]

Does the trailer have brakes? Does the trailer and truck roll easily on a slight hill in neutral?

Even a 4 cyl ranger can pull a 2500# trailer

 

[Turdle]

It would be good info to know fuel pressure under load. Since the filter made a noticable difference, wondering about the fuel pump to be honest.

 

[410Fortune]

yes a weak pump will be able to deliver fuel, but may not be able to deliver enough volume when under load

 

[FMSD16]

It would be good info to know fuel pressure under load. Since the filter made a noticable difference, wondering about the fuel pump to be honest.

What should the pressure be at idle, under load not towing and under load towing, that is a good point…

 

[Turdle]

I believe 60 psi in all above conditions.

 

[410Fortune]

65 psi is spec, +/- 5 psi

 

[boominXplorer]

Change spark plugs, it's a 3v engine and plugs is the root cause on power loss on those. Since your an 08 you need to check coil boot color before buying plugs.

 

[FMSD16]

Change spark plugs, it's a 3v engine and plugs is the root cause on power loss on those. Since your an 08 you need to check coil boot color before buying plugs.

Its all brand new since about 6 months ago, all in good working condition. It has the brown boots so it has the short shank plugs..