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mgilbert

2007 granite ai-460 falls off throttle when pulling

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It will be pulling fine foot mashed to floor and then it feels like you let off throtlle for 5 seconds then picks back up and does it again

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Has the truck always done this? If so, there are several threads about this problem, Doing the "Step 12B" download seems to help alot. Mack knows it as the "poor throttle responce program". We do sometimes 2 or 3 a week here. Give me the last 6 of the VIN and I can see if it has been done,

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bought this truck used and has done it since we got it, We had in shop yesterday hopefully they'll get it this time but here is vin 055983

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Just had a chance to pull up your truck and it looks like a Mack dealer just did the step 12B update the other day or at least downloaded onto their laptop to install in your truck. With the T-318 transmission, 4.73 rear gears you should be spec'ed right if you have tall 24.5 rubber. Spec'ed like alot of the trucks around here, some go with the taller 4.42 rear gears for more top speed but your OK.

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any chance you can check if this has been done on our 2005? 022331

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I have a 04 AI-375 that does same thing.  Right when it goes to full torque it cuts back to 70% for 5 maybe 10 seconds and then turns loose again.   Replaced one unit pump and injector that had multiple faults.  Not as bad but still does it.  Been in shop multiple times but no success yet finding problem.  

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Can you check if the step 12 b was done on my 2006 ai 460  #040012

Thanks Dan

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11 hours ago, nelm1994 said:

Can you check if the step 12 b was done on my 2006 ai 460  #040012

Thanks Dan

Your Vehicle  ECM is at  Step 12 as of now. There is a Step 12A and of course  the 12B. There might be some other engine files as well.  Assuming your truck is a CV713

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On 3/4/2017 at 6:41 PM, MAC said:

any chance you can check if this has been done on our 2005? 022331

Yes yours has the Step 12B software  installed

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On 3/5/2017 at 7:29 AM, jmb4wd said:

I have a 04 AI-375 that does same thing.  Right when it goes to full torque it cuts back to 70% for 5 maybe 10 seconds and then turns loose again.   Replaced one unit pump and injector that had multiple faults.  Not as bad but still does it.  Been in shop multiple times but no success yet finding problem.  

We just had CV in the shop doing the same thing.  The throttle pedal wires at the VECU are shorting out on the kick panel in front of the passenger seat , Pull down the black kick panel, 4 screws on top and 2 at bottom  at the floor. Lay the panel down look very closely to all the wiring and how they lay and contact the panel. You will probably see rub marks on the panel where the wires come out of the VECU and ABS  ECM and loop back to towards the fuse panel.  Repair wires if bare copper is visible . Tape up all wires where hopefully they wont rub and short out again. We have seen this many many times. And will not set a fault code most times. 

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maybe the fuel transfer pump . our DM690SX w/AMI335 engine acted  like that because the pump gear was slipping on the shaft

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