I posted a couple weeks ago about this. Since then, the dealership changed out the CATs. It made sense but it didn't do anything to help out. On a warm day (90 degrees and above) the truck gets sluggish, the temp gauge rises about halfway (only under load) and my gas milage is around 11.5. I've got the truck at the dealership this week and basically told them to figure it out or buy the truck back from me.

Any help or sugguestions would be greatly appreicated.

 

sounds to me like the system needs a good back flush to get rid of debree in the radiator. also under load the truck will tend to rise in temp. other thing is check the fan and see if the clutch is still good. alot of times the clutch will go without warning. if the fan spins frely it is bad, or if you can rock the fan back and forth.

 

as for poor mileage. check the plugs. you may need to swap them out. most of us are running the autolite 3923 plugs, gapped at .040. truck seems to like these plugs any platinum plug will kill mileage, have to stay with the copper core

 

I put the autolites 3923in about 10k ago and they've been working great but the tech did mention to me that they need to be the champion plugs. I told him to just go ahead and swap them out just to try to figure out this thing.

I'll have him back flush the radiator. I've got the jet chip T-stat in there, I wonder if he will say something about that. I took out the jet chip prior to taking it in.

He is putting in another new set of CATs today and then running it without the exhaust connected to seeif he can figure this out. I'll update once I hear back from him today.

I checked the fan a couple of weeks ago and it seemed fine. I'll have him check it as well.

 

tell him to check and replace the egr valve. it is another thing that can go bad and not toss a code

 

I'll do. I should have an update later this afternoon.

 

The tech put new CATs (again) in yesterday, updated the software, and changed the plugs - still didn't help. He is going to check the egr valve today along with some other things.

I was thinking this morning. I've got the Fastman TB. Would that be causing the the truck to get sluggish when it is hot outside? Just trying to think of everthing that might be causing this.

I'll update later today.

 

I don't see how the Fastman TB would affect that, not to mention others have it and haven't experienced that problem.

 

Update: I just got my truck back this morning. It ran normal all day, even when the outdoor temp was 97 degrees, and the gas milage today was 15.3 which is much better than the 11.5 I was getting.

The dealership replaced the PCM and O2 sensors as well. I don't think they could pin point what was going so they just started changing parts until they got it.

 

Seriously? I've noticed a decline in response and power lately, decided to check the fan. I can spin that sucker all the way around easily.