Bigjohn4300

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Hey we both have the same issue, sometimes my 04/300/Allison does the exact same thing! Sometimes from a dead stop, almost instant boost, good power...sometimes normal power, then sometimes won’t build good boost through first/second maybe into third before you hear the motor pitch deepen(more fuel)followed by rise in boost and normal power.

So if I read and am understanding correct, all of the ccrs motors, from the 300 to the 460 use the same EUP p.n.?

Had the same issues when hot(above 90) and grossing 81, pulled rad and had it rodded out, stays on lower end of green now

I had to go to three different dealers before i finally found one who would update my 04 AI from 9B to 12B, and it took that shop almost half a day to actually get it to work, they had to flash it (called it that i believe) several times before it "took". Sounds like we are chasing the same intermittent low power issue

Ill have to second what "HatCity" said, my local dealer couldnt/wouldnt take mine from 9b to 12b, but a dealer 80 miles away did it. They had to fool with it quite a bit, took three attempts to get it to take, but they got it. Didnt correct my main issue of intermittent low power, but it did reduce its severity and frequency i believe. But it did introduce a 10 minute idle shutdown i didnt have before, need to see if the local dealer can kill that off

Quite as stock?

Awesome! Guess I don't need to email him anymore requesting part numbers, please post when you come up with a high flowing "quite" 5 in 5 out muffler

Nice truck!

Yea he was kinda a jerk once someone located the truck for him

Btw the trans in this truck is a 4500rds, not a 3 series, that model, in that year truck, was available from Mack behind the 427 and lower ratings, but the 300 and 375 versions were supposed to be mapped for best performance behind the allison.

I think I'm going to try the 375, but I believe I'm going to want more in the end. If it was a truck that the drivers use, I would be reluctant, but it's only me, the repair bill check writer (and my personal truck) so I believe it wouldn't be abused. My local Allison shop head tech is a personal friend from high school, he feels confident, on this model Allison, to around 1700 foot lbs owner driven

On the passenger side, standing on the ground, there is a rubber sleeve that couples the A/C blower discharge duct to the inlet side of the evaporator, a Phillips screwdriver and a few minutes time removing the inlet duct(slide the rubber to the right or left to allow the removal of the duct, can't remember which way) and your staring at the inlet side of the evaporator, which I'll bet a donut on, is nearly 100% plugged. Clean it with a vacuum or wash it in place. One of my old drivers likes riding with the window down, A/C on, dusty air through a cold evap coil, damp from the S.Louisiana air makes a muddy mess! I have to clean his every few months, complaint from him? A/C not hardly blowing

That would be great, I've been told 427 up is where it it takes iron over electronics