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Mack AI460 AI427 AMI low torque low horsepower poor fuel mileage granite , dead dog , remediation


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Pressure checked from turbo discharge to the inlet of the intake manifold to 35psi, one minor leak in a hose coupling was replaced. Under full throttle(while actually pulling)she will put up 40-45 lbs boost(gauge flutters above 30ish psi) and pyro around 800. But when not pulling good(stealth mode i call it), she wont build more than 15-20 psi, 300ish pyro. Release throttle and floor it once or twice, most of the time it will apply fuel, and goes to pulling. She is still set at 300A hp, waiting on Capitol Mack to get approval for 375A uprate. Btw, I forgot to reply to the replies calling for a heavier throttle foot.....i promise if i pushed it down any further i think it would go through the floor! At 83k @ 300hp its a long climb to 50. I found two grounds and cleaned them again, looking today for others. Also, is Hewitt pyro and boost instruments decent stuff?

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By the way you describe this it sounds like a torque limit switch wiring issue to me!  if its a mack trans check the wiring to the switch on the range cyl on the upper  back of the trans if so equipped! If u have  access Vmac software check to see if the torque limit is enabled!

 

Just sayin!

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  • 3 weeks later...

She is going in soon to Capitol Mack to have the HP setting uprated, and i will ask them to turn off torque limiting if that can be done while programming (its a 4500 series allison, may have to stay on), correct speedometer error, and "allspeed" governor setting. My dealer is asking for what injector number i put in her, says Mack wont release the uprate file unless I put the correct injectors (it has K&S fuel reman 400 hp injectors). Funny they want to know which injectors, but not turbo. Seems like somewhere in this thread i saw something listing the different injectors and other parts by HP, Ill look around. 

BTW she is running much better, still the intermittent low power, but i was told to change the EUPs, original to the engine, 20 thousand something hours on them so probably due.

Is anyone well versed in the correlation between turbo sizing and EGTs? At 60 MPH/1400 rpms, EGTs are 800ish empty, 900ish loaded at a steady state speed, but ask for more speed, boost climbs and EGTs drop (75-100 degrees). Im wondering if this means that the turbo is maybe too big at cruise? I know i was told to stay below 1000 in general, is 900 too hot?

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That is the number that i gave them, 419 M2 (400 hp), but apparently that number has been superseded, and they are saying they cant uprate it unless i buy the other number and install them first🙁. I hate to spend $1200 more and the time to change them, im going to try another dealer and see what they say, i think they are trying to sell injectors.

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  • 4 months later...

Would somebody have the part numbers to change exhaust manifold to the pre ai style for an MR? We had to have the camshaft replaced by Mack due to scoring on it so they put the older one in it. That’s been some months ago and I personally drove it today for the first time. It may have a bit more power but it’s hard to compare it after all this time. Now I’d like to change the exhaust manifold. Do I do the ends too or just the center piece?

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"N".. You have an MR?   The outlet on the center section should be specific the the truck's body...  They can crack on the backside middle, and the partition in the outlet. The ends should be the same P/N, and the center section should be 'vehichle specific' .. Jojo

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  • 3 months later...

what you are posting is about the injector cup... the injector only nee a light lube like assmbly lube to lube the o-rings and hold the seal ring in place for installation..  so what are you actually replacing?  jojo

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2 hours ago, Joey Mack said:

what you are posting is about the injector cup... the injector only nee a light lube like assmbly lube to lube the o-rings and hold the seal ring in place for installation..  so what are you actually replacing?  jojo

I'm replacing the injectors, I guess I misunderstood the manual.😅

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no sweat..  clean the injector bore really good.  assemble the injectors/ o-rings and base seal, line it up with the notch and tap it in to place. torque the cap to 45- 50 lbft. then install the fuel lines according to Mack spec... they are 'torque conditioned' on install..  basically 45lbft, then back it off and torque to 25lbft... supposed to have a crowfoot wrench and the formula to do it right....   whatever......  pull 45 then back them off and then pull 25+  just use your skilled hands...  jojo

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13 hours ago, Joey Mack said:

no sweat..  clean the injector bore really good.  assemble the injectors/ o-rings and base seal, line it up with the notch and tap it in to place. torque the cap to 45- 50 lbft. then install the fuel lines according to Mack spec... they are 'torque conditioned' on install..  basically 45lbft, then back it off and torque to 25lbft... supposed to have a crowfoot wrench and the formula to do it right....   whatever......  pull 45 then back them off and then pull 25+  just use your skilled hands...  jojo

Yea , when I did the manifold, I used the crows foot to take them to 30lbft .

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I have an added sequence when installing injector lines! It involves tightening the the injector down snug then backing it off to just touching tight! Then tightening  and torquing the line ! Theory behind this is it allows for the injector to find its happy place if there is any variance in the alignment ball in the head! Not sure if it helps on the e7  but have done this for ever! As we used to have issues with the V8 Lines back in the day, specially when they converted to the Robert bosch fuel pump  and were using the ball for elinment on the injector it seemed to help doing this! just something to try if you have a leaker!

 

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On 10/28/2021 at 9:52 AM, fjh said:

I have an added sequence when installing injector lines! It involves tightening the the injector down snug then backing it off to just touching tight! Then tightening  and torquing the line ! Theory behind this is it allows for the injector to find its happy place if there is any variance in the alignment ball in the head! Not sure if it helps on the e7  but have done this for ever! As we used to have issues with the V8 Lines back in the day, specially when they converted to the Robert bosch fuel pump  and were using the ball for elinment on the injector it seemed to help doing this! just something to try if you have a leaker!

 

Thanks for this tip...can you tell me the allen wrench size of the injector hold down plug.thanks again

 

Red

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9/16"  i made an allen socket of  sorts with a  3/8" bolt and a regular nut and a lock nut and screwed them on the bolt and jammed them really tight in a vise, so they can take the 50 lbft of torque...  jojo

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here is a sample...  sometimes I put a spot of weld on them to make sure it will hold, especially if im taking a pitman arm off, and on...  If it breaks when the job is done, so-what..  or just buy the real socket. I guess it depends on how much downtime you can afford..  I guess this is my Boyscout way of getting the job done.. :) Jojo

KIMG0695.JPG

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27 minutes ago, Joey Mack said:

here is a sample...  sometimes I put a spot of weld on them to make sure it will hold, especially if im taking a pitman arm off, and on...  If it breaks when the job is done, so-what..  or just buy the real socket. I guess it depends on how much downtime you can afford..  I guess this is my Boyscout way of getting the job done.. :) Jojo

KIMG0695.JPG

Lol..I did this once to take the cap off the pitman arm on my  the steering box .thanks to the magic of Amazon prime , a 9/16 Allen wrench socket will arrive tomorrow at  my door.

Edited by R.E.D
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I may have made a boo boo again.. is it 5/8" and you use a 7/16" bolt...  unbelievable..... i just did this 3 weeks ago and my brain just 'farted' I hope you get what i'm saying....  Too funny to me.... jojo

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it's funny how i'm forgetting the sizes, when I change steering boxes and injectors in e-tech's often,  I can go right to my tool box and grab what I need first try, but forgot the sizes for this post.  i'm going to go to my service truck and dig out the tools.... Too funny, jojo

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