Performance Change

[Spindrift]

Our trip home this weekend was going well...until we stopped to refuel. Although it was a relatively short trip, without significant long climbs, the power and lower EGTs from the new ECM were definitely noticeable. I saw a marked decrease in engine performance after taking on a full tank of fuel. Where I saw moderate hills and EGTs in the 700-800* range before, after the refueling I saw EGTs in the 900-1,000* range. The only two things that I recall being different are the refueling and rain/wet road conditions. Since this fuel stop only added approximately 275 pounds of weight to the truck, I'm surprised.

I coulod be missing something very obvious. Any ideas?

[BuffaloGuy]

Perhaps you filled up with #1 instead of #2. That will do it.
Ken

[Spindrift]

I confirmed that I filled up with #2.

[BuffaloGuy]

Did you check/change your fuel and air filters? The added weight means nothing to these trucks.

[Spindrift]

New IP and fuel filter installed prior to the trip. There are 8K miles on a cleaned and re-oiled K&N.

[charliepeterson]

Fuel quality can play a big part in how these trucks run. Try adding an extra dose of fuel additive for this tank and refill at a familiar station and go for another short trip.

[Spindrift]

Fuel quality may be the issue. Even though I filled at a major truck stop (Pilot), I was surprised by the low cost of fuel...$1.59. On the other hand, would a large company like Pilot mess with their diesel fuel blend knowing that they serve a large percentage of the trucking industry. Then again, I may be naive.

[BuffaloGuy]

Even though you re-did your filters right before the trip they still could be in need of service. A bad shot of fuel can plug a fuel filter right away. Air filters have been known to get plugged pretty quick too. I'd check 'em both anyway.

I've actually got a pressure gauge on my fuel line so I can tell when the fuel filter gets loaded. Pretty helpful.

Ken

[TurboDiverArt]

<<SNIP>>
Air filters have been known to get plugged pretty quick too. I'd check 'em both anyway.

<<SNIP>>
Ken [/QB]I will second that. I put in a new UNI foam filter and 5000 miles later I needed to clean it. It was totally black and greasy/gunky on about 50% of the filter and the rest was just dirty. Bugs, a few bees and greasy stuff. I use my truck on the highway mostly. I was very surprised. As a side note, I never thought the spray on cleaner would clean the filter because it was so greasy and dirty. I was extremely pleased when I sprayed it on, let it sit for 5-10 minutes and then just hosed it off and it got all cleaned. It just took time to dry, even when using a shop-vac.

I'm not 100% sure I had the filter set properly in the air filter box correctly. When I checked it a few weeks ago and first noticed it being very dirty, I think the filter side that connects to the pipe was not seated properly in the air box. This might have been a problem as that side of the filter was the dirtiest, not at the fender intake. The inside of the filter was nice and clean so it wasn't coming from the turbo.

Check it, takes 2 minutes to do. You might be surprised, I was!

Art.

[Spindrift]

Good points. I'll re-check air and fuel filters. Makes me wonder, though.

How do you know if you've used too much, or too little, of the spray-on oil? Seems to be more art than science.

[damork]

You might be on to something - I steer clear of their truckstops and use only fuels I have really tried and trusted (along with addtion of a water trap/filter ahead of the lift pump). Maybe it was coincidence, but problems I had with pumps all began when I got my first batch of fuel from them. I'm not too fussy when buying gasoline, but there really seems to be some differences in diesel fuel and the quality of it.

[Bobbie Martin]

Originally posted by Spindrift:
How do you know if you've used too much, or too little, of the spray-on oil? Seems to be more art than science. Its very easy to over oil a K&N. The flow drops dramatically when you do. Most people over service them as well. Unless you drive off pavement a lot, servicing every 50,000 miles or so is all you need. You can find oiling instructions HERE (http://www.knfilters.com/clningins.htm).
When you noticed the increase in EGTs, did the boost change as well?

[Spindrift]

For some reason I'm programmed to pay stricter attention to EGTs than boost. Unfortunately, I don't recall whether or not there was a direct relationship between rising EGTs and boost. Why? Are you suggesting that the problem may be more filter related than fuel related? If so, the filter doesn't look any different than it did prior to the trip.

[Bobbie Martin]

No, just wondering. If the power dropped, then boost should have as well. Sounds like you got more fuel or less air, but since it happened at refuel time, hard to tell. Have you added any more fuel or treatment since the problem started?

[Spindrift]

I haven't added more fuel. I'll be doing a lot of driving with the truck this weekend, but it won't be under load so it will be difficult to monitor what effect there will be from more fuel additive, but I'll try it. Might as well clean the air filter while I'm at it; certainly won't hurt. Has anyone else heard about poor quality fuel from a Pilot Center?