O4 379 MBN 24234 C15 Cat Poor fuel and power

If that is so, could you tell me what is wrong with my truck? I also know several other people who also have the same problem, and we'd like to get a wider power band out of these bridge engines. You and Phil are MORE than welcome to come to LA. and show me how to run this truck, or figure out what is wrong with it. I will bet money that if you try to climb any hill larger than an overpass you WILL stall out below 1300 rpm. Read my past posts complaining of this problem, and comparing this engine to either of my previous two trucks where I let them pull down to 1100-1200rpm, and up shifted at 1400. YOU CANNOT RUN THIS TRUCK LIKE THAT!!!!, IT WILL STALL!!!!!!!!!

 

Droy,
Give me your engine serial number and drive train specs and I'll see what I can give you.Also need tire size and type of trailer you pull.

 

MBN26205 475hp at 2100
RTLOC16909 AT2 (HAS been converted to 13 speed)
3:36 on 24.5 standard height rubber
Pulling chemical tanks (smoothside, insulated trailers); MT weight= 32,000, to 34,000 depending on fuel level, and whether I'm hooked to an aluminum or stainless trailer.
Gross weight does not exceed 80,000, more often around 78,500.
80% of my traveling is "regional" - LA, TX, MS AR, AL (listed in order of most traveled).
Purchased this truck used from KW dealer in FT. Worth, TX. 04/01/08 when mileage was approx. 552,000, now at 612800.
ECM showed lifetime mpg average of 4.86@ time of purchase. (no knowledge of trucks former life). My mileage has been from 4.95 to best of 5.36; this is my calculation, which is done # fueling. I do factor in a 7% difference in mileage, due to my replacing the lo-pro tires with standard height tires.

 

Thanks Droy,
I plugged in your specs into Cat's spec'ing software program and with the taller tires and the 3.36 ratio you really have a setup for nice low rpm at your cruise speed. At 72 mph in top gear, I'm showing 1386 rpm and projected mpg of 5.07 based on 78500 GCW, level ground, 70 degree air temp and no wind of course.
The negative here for you is with the 3.36 gearing your gradability in top gear is only 1.08%, which explains why your reporting poor performance in the hills. Cat recommends 1.8 % gradability in top gear for acceptable performance. For you to get that, you need to drop a gear to 12th which gets you close (1.78) or if it's a steep grade maybe even 11th gear ( 2.46).
The numbers I'm showing (in brackets) are actually the percent of the grade you should be able to pull in that gear based upon your specs and hp available. Most interstate off ramps are 2-3% grades.
I also checked your serial number in Cat's system and there is absolutely no history at all on your engine. It does show the original owner as RGB Transportation out of El Paso, TX
Hope this helps answer some of your concerns.

 

Thanks for the info, and once again, dropping a gear or two is more often a necessity rather than an option.

 

E500GVR;
Is this program something I can access, or do you have to be some sort of Cat associate?
Thanks again.

 

Cat has a limited public version of "Design Pro" on their public site http.ohe.cat.com that is pretty slow but should work for you.
Also, I forgot to mention your 475 rating is a 1650 torque rating. Cat did also offer 1750 and 1850 torque ratings for that model. The turbo, pistons, and injectors are all the same parts so it could be reflashed to a higher level now that it's out of warranty. Under the original warranty, they wouldn't allow higher torque cause your transmission is probably rated 1650,but, I think your original 9 speed was a top 2 which I believe may approve 1850.
An additional 100 or 200 lbs of torque would certainly improve your grade capability if thats your objective.

 

2007 and newer engines are different with different materials used, you will melt a piston down on a MBN if you hold it at 1200*F for to long, i have seen it happen a lot with guys who get carried away running pittsburgh boxes.

No eaton wont cover the trans because they will say drivers abuse.

Once again computer programs and real life are two different things, im not some steering wheel holder with his head up his ### who needs to be told how to drive a truck..... If CAT had their crap together they would take some tips and actually build an engine that would get decent millage and have LOTS more power.... But then again the EPA is the problem. Just wait for a dyno from mine here in october, hopefully its in the quad digits at the tires and im averaging around 7mpg with mine, driving it the way i drive it without lugging or progressive shifting.

 

Rat, you mentioned you had a 379, I've never owned a Pete, but those my dad owned had a manifold pressure gauge instead of a boost gauge. Either way, the manifold pressure gauge should measure just that; and the boost gauges I am familiar with are usually hooked into the manifold, so they are also a manifold pressure gauge in actuality. Hooking the regulator up where the boost sensor was should insure that just the sensor reads the regulated air. If by some chance your gauge is tied into the same spot, just be sure the gauge fitting is between the regulator and the engine manifold.