Plugged Cat? Slipping Clutch?

[Trapper77]

So, my 2003 has been real good to me. Never been in for anything besides the hose replacement and the new belts. Bone stock right now, right down to the tires. It has 52,500 on it. I took a long trip, 3000 miles in a week, pulling a 24 foot utility trailer. Total load with the truck and trailer was a little over 16,000.

Since I have gotten back from this trip my mileage has gone down considerably. I know my mileage drops as we start getting into winter but this is more than usual by a couple of miles a gallon. While on my trip I was limited to places to fuel up but I think my fuel was ok. Changed fuel filters after I got back, have yet to ever have a water in fuel light come on, and all looked good. Oil has recently been changed per usaull as well.

I have done nothing different to my truck than normal. I usually don't tow this kind of distance and I always fill up at the same place in town. I have ran a couple of tanks of fuel from my dealer already to no gain.

I do notice that when I am at 2000 RPM my speedometer is reading a little under 70 mph. It seemed like before I was right at 70 mph at 2000 RPM. I could be off though and just paying more attention to it.

Some guys have said that the cat might be getting plugged up and restricting my exhaust. Anybody had this happen? I know older 80's cars got the cats plugged on them over time but should this be something I have to worry about?

Do you think maybe my clutch is slipping a little bit?

I am getting real worried about maybe bad injectors, although my oil is clean.

Am I being paranoid? Can anybody help me out with what might be the cause of my drastic mileage decrease? I have hand calculated all of my mileage from the start and have all of my records of fuel, mileage, gallons, mpg etc in a spread sheet. That is why I am concerned.

Thanks in advance

Trapper

 

[Kleetus]

You should be able to see a climb in RPM if your clutch is slipping, and it would probably be more noticeable in a lower gear, say 4 or 5th, where you can really get into the power range of the motor, and when it goes, it should really climb without a gain in ground speed. This is something a passenger would notice, so it's not that subtle.

Have you noticed any decrease in performance, other than the mileage loss? Still runs strong? If it's a plugged cat, it will really run like crap. I assume you don't have any guages, so EGT readings probably aren't going to be much of a help.

None of these events really tie together well though, it's like you have separate problems. How much is your mileage off by? I'm almost wondering if you have a bad speed sensor, and it thinks you're going slower and less distance than you really are.

 

[DaveBen]

The cats don't get plugged on these trucks as a rule. Are you seeing the seasonal drop in mileage due to the winter fuel? It will stay a bit low until spring when it will go up again.

Dave

 

[Trapper77]

Well, don't know what the deal was but it apparently is gone. Went on a 1300 mile excursion this last weekend and averaged a little under 19 mpg hand calculated. The reason I was asking about the cat was because this muffler guy was telling me that these diesel cats plug up really fast and are a pain in the butt. I thought he was full of crap but wanted to hear from the experts instead.

I really don't know why the big difference in mileage. Same fuel, same driving habits. I guess I was just paranoid. Thanks for the info guys.

Trapper

 

[Kleetus]

You didn't happen to get a tank of Ultra low sulfur joke fuel did you? If that's the case, we're all screwed...

 

[Trapper77]

I don't believe so Kleetus. I have been filling up at the same station. Same stuff when mileage was bad as when it was good. Maybe they slipped some in on me but I have not seen anything different on the pumps.


Trapper

 

[Kleetus]

You're probably right about your local brew, but weren't you on the road when this happened? Maybe the stuff you picked up was that bad and took this long to dilute with good fuel to be more palatable to your engine? Hard to say, maybe something like the EGR was sticking ever so slightly? Unless it happens again, I'd probably not worry that much about it now...

 

[W4RLR]

What does a feline with constipation have to do with a slipping clutch?

 

[Trapper77]

I was wondering if the lack of fuel mileage and rpm change was a result of a plugged cat or a sliping clutch. If the cat is plugged the truck won't breath so mpg goes down as well as power. If the clutch is slipping the mileage will go down as well as power. Different symptoms can have the same result. Turns out it was neither and I cannot duplicate the problem since it happened.

Trapper