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My 2006 LBZ 280k miles (285/65-18's, 5" exhaust, EGR blocked, and running a hypertech on level 3) has some odd sh*t going on. Going down the road to work (cruising about 65 on the freeway) it will get about 17mph avg. I think it should be higher, but I'm going to blame it on winter fuel and running oversized tires.

When I pull my enclosed 18' trailer with a couple dirt bikes in it things get a little interesting - mileage goes out the window. The trailer weighs about 6k - nothing remotely crazy.

In the past cruising at 60-65, down a nice flat open stretch of highway and I'll get about 10-11 mpg. If the horsepower gods are smiling on me maybe 12 mpg with this trailer. (This was going to be my last trip before I dug into the issue because this is NOT normal) I would expect fuel mileage to be around 13-14mpg. But the truck feels like it's pulling a damn house. I've got a 3500 LLY 12k lb excavator and dump trailer that all in all weighs about 28k lbs going down the road and it pulls that just as well as the 2500 pulls the enclosed trailer!? (I mean across flat ground - obviously a hill is a whole different ball game with that much weight).

This weekend thins got a lot worse though...

Leaving the track I stopped to grab fuel before heading home - about a 250 mile trip, most of it is flat, there is one hill that's about a 6% grade for 4 miles and then 1 mountain pass towards the end. Basically driving through the plains and rolling hills (maybe a slight breeze for a head wind ~5 mph?) I was seeing about 1200-1300* EGT's?!?! AT 60 mph?! Truck doesnt blow any smoke or even the slightest haze. FRP was at 23k-24k psi and cubic fuel rate was in the 90-100mm^3 range. So it was fueling almost as hard as it could. Just to maintain 60-65mph I was running at about 50-55% throttle input (all measurements are from an Edge CTS monitor). Boost was only running about 5-9 psi during this time. I feel like the truck should've been making more boost and using less fuel. I manually dropped it down to 5th gear to get a little more rpm (1900-2k in 5th) to help drop the EGT's and this brought them down to about 1100-1200* - most everything else remained unchanged.

I went through an entire tank of fuel in about 105 miles!!! There was a pretty decent hill in the middle of the trip - but nothing crazy. For reference in my old 2003 Cummins I made the same trip with the same trailer and still had a 300 mile range left. I know its a little apples to oranges - but I'm just saying that the fuel consumption was ridiculously high.

Mid way home I put the stock tune in it - and it didnt change a thing. EGT's were maybe a little lower, and mileage a little worse but nothing too much.

I can hear the turbo vanes change at idle and then on decel I can feel the exhaust brake working and I can watch the vanes change on the screen too.

Checked trailer brakes and bearings before this last trip over the weekend and everything was perfect (trailer is about 2 years old so it should be fine).

Fresh fuel filter on it right before I left. Merging on the freeway after one of my fuel stops I did see it hit about 20-22psi boost, so I dont think it's a boost leak. Plus if it was a big boost leak it would be rolling a little coal or at least a haze - but it runs as clean as a Prius.

One thing I did find odd was that the fuel temps got really high - upto 156* (didnt hit the 160* limp mode mark though I backed way out after I saw 155 and it ticked upto 156 before dropping). Injector balance rates and fuel rates at idle are all fine (highest is 1.5 and lowest is 2.1 at idle in neutral, and in gear they get even closer to zero).

So why in the world would the truck be fueling so hard, and making so little boost - but not blowing any smoke? I have a couple different hypothesis about what it could be, but I dont want people to start thinking down the same road I am, I want people to do their own reasoning and see if there are any other ideas? So what in gods name do you guys think it is? and what I should check?

Only codes are P0401 and then 2 glow plugs. The 0401 has been on since I did the EGR block off about 25k miles ago so it's not that.
 

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First, with Hypertech you can NOT delete emissions stuff without some kind of issues, probably related to what your dealing with.
P0401- "Exhaust Gas Recirculation Flow Insufficient “ because you’ve deleted the EGR and you don’t have a tuner that deletes emissions stuff.

Hypertech claims you don’t need a EGT gauge with their safe tunes :surprise:
I disagree but at least you have a EGT gauge for the truth.
Level 3 your adding a good amount of hp and torque, doing that you’ll see higher EGT’s.
 

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Discussion Starter #3
First, with Hypertech you can NOT delete emissions stuff without some kind of issues, probably related to what your dealing with.
P0401- "Exhaust Gas Recirculation Flow Insufficient “ because you’ve deleted the EGR and you don’t have a tuner that deletes emissions stuff.

Hypertech claims you don’t need a EGT gauge with their safe tunes :surprise:
I disagree but at least you have a EGT gauge for the truth.
Level 3 your adding a good amount of hp and torque, doing that you’ll see higher EGT’s.
Agreed you cannot delete emissions stuff - it just has a CEL constantly. Not a big problem because I've gotten used to ignoring it.

Hypertech never once has gotten to the point where I was worried about the EGT's hurting something. My issue is how high the EGT's are based on the given condition of flat ground cruising down the highway. THAT is way too high - I dont care what programmer that's not right.

Level 3 on this programmer is only a 100hp tune - its always run really clean, and never over fuels, so I'm not sure why the EGT's are so dang high cruising along.
 

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Have you tried #1 or #2 to see if there’s much of a difference with EGT’s ?
Cruising those temps are a little high unless maybe upgrade and or head wind.

Actually adding 100 hp power is a little more than you think, especially if your towing that can be a 'uhNo.
For longevity 25-50 is fairly safe, constant 100 IMO isn’t, trans is considered safe with 80-90 “maybe”.

Also with your EGR code that could possibly be affecting this, electronics can act goofy at times for reasons causing goofy things.
 

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Isn’t Level 2 on the Hypertech a ‘tow’ tune?
Might want to try making the same pass with the EGR unblocked and the codes cleared. I think that’s you’re problem. Tune doesn’t recognize the EGR block and is trying to over compensate. I don’t know why else you’d have EGTs so high and everything else running normal temps/pressures.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #6
Level 2 is the towing tune, but its not a big tuner - I could understand seeing 1300-1400* if I was climbing a hill or going into a 60-70mph head wind.

I grabbed a friends 24' enclosed trailer and got 14.4 mpg and EGT's were in the normal range. I think this basically narrows it down to being the trailer at this point. Checked brakes and wheel bearings and they're fine, so I'm going to check the alignment later on today. Just wanted to close the loop for someone in the future. Never overlook the trailer - it might not be the truck...oops.
 

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Wow, high egt's and you're reading 12-1300? That's not really that hot... My LBZ that I had a few years ago did those temps pretty consistently, and it had some great tuning on it- I wish I could have copied that tune for the other two I've had since then. But I've seen over 2200* out of my LB7 before, and consistently been 15-1600 on a completely stock engine before. If there are other things that concern you, then look into those and see if it changes the temps any, but I wouldn't be concerned about 12-1300 degrees
 
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