Mackpro

The fuel sending unit wires go to the VECU (ECM in passenger side kick panel) first then comes out of the VECU and goes to the dash cluster. Usually if there is a wiring problem between the fuel sending unit and the VECU it will set a code(yellow lighting bolt).

Havent heard of anyone using them. There were several threads on the AI engines, lots of things to do and check, tire size, gear ratio and transmission make a huge difference. Mack dealer software updates can make a difference. I am workin on one now that is weak, Its a 427 AI, 4.42 rear gears, tall 24.5 rubber and an 8LL Fuller trans. Did all software updates (step 12B), adjusted valves, installed upgraded rocker arm hold down bolts, pressure tested aftercooler and intake manifold and piping. Driver was in a hurry but called back to say much improved. In my opinion it needs 4.64 gears or drop down to lo-pro 24.5 tires but the customer doesn't want to do it. Whats the specs on your truck? Last 6 of Vin would help and I can pull it up.

We were denied warranty on a 2011 truck, on its second trip an injector actually broke and because we didnt follow proper procedure we were denied and now have to apeal. Thats all I can say about it without getting some kind of pissed off.

Heres the service bulletin on keeping the new cooler from going out again. However it probably will go out again, a fleet of CXN's here have 600-700 thousand miles on them and all have had their EGR cooler replaced at least 3 times even when following all the service bulletins from Mack. The coolers come from Mexico if it matters? oil cooler inlet screen.pdf

Is it a CH/CX or a CV Granite? I see you have CX listed in your profile. So I assume it is a CX, EGR coolers go out like crazy on these engines, The EGR cooler is the metal box on the RH side of the engine, remove the rubber hose between the EGR cooler and the metal "S" pipe (mass flow sensor pipe)that goes back over the engine (between/over the valve covers). If there is coolant/water (wet)in this pipe then more than likely the EgR cooler is bad. Is the coolant coming out of the exhaust manifold it's self?

Our new truck sales have really shot up here in the last 2 months. Sold 2 new 2011 505 HP CHU's on new years eve. We now have several 505HP SCR engines running in our area. Our truck sales were ordering more today.

All those circuits run through the turn signal switch, when i have screwy problems like that I always start by replacing the turn signal switch.

We have sold 5 new 2010/11 truck with the SCR/urea injection, all 5 have had no issues with any on the emission controls.

Is there a specific part of the wirin you need to see? Our diagrams are very large but if you need a specific circuit I can scan it for you.

Not to get off subject, I drove a CHU with a 505 HP today and the boost was going past the 40psi guage, what a ride!

Forget messing with Mack, go to a real turbo shop and have them make you one up. We use United Fuel and Turbo in Birmingham Alabama.

Mack used to say 36" between the trailer and truck but 40" seems more realistic ( look at a UPS truck going down the highway, really close). Adding of thoses aero fairings that bolts to the bottom of the front bumper would also help. Between 1992-1994 we sold 50+ CH sleeper trucks to a fleet, when the MPG didn't meet what they were promised we added large roof farings with 12" sleeper extensions and this alone put them into their target MPG range. There used to be a Mack engineer (cant remember his name)that had a great list of goodies to set a truck up for MPG,you could call him up direct and discuss your specific set-up, sadly most all thoes great engineers were replaced by Volvo guys. Since Volvo took over I have yet been able to talk to a engineer.

Different turbo and injectors in the two engines. You might be able to turn the 460 down to a 427 with nothing more than a download. Most all ASET AC engines are exactly the same, just different turbo, injectors and download change the HP level.

Check the muffler, I spent a day on a lowpower complaint and after checking everything I could think of I climbed up a ladder and with the engine running I could cap off and hold the exhaust back with my hand. The baffle had come loose and was stuck side ways inside the muffler.

Here are things we do to try for top MPG on ASET's , adjust the valves(and jakes) and install new rocker arm hold down bolts( due to possible breakage), replaced the boost pressure relief valve on the intake manifold ( if you havent already replaced it), load the newest software and datafiles in both ECM's ( step 12B as its called ), calibrate throttle pedal and VGT turbo, pressure test the complete intake system including the EGR cooler piping, replaced the muffler with a Walker straight through muffler ( still quite), make sure there are coolant shutoffs on the fuel heater for summertime (keep them closed till it gets real cold), Figure out what MPH you want to run/cruise and talk to a good salesman how knows all the fourmulas for getting the correct tire size for the rear gear ratio and trans that you have. Sometimes a simple tire size change (without changing wheels) can get you into the "sweet spot" you to be for best MPG. We have seen trucks that were spec'ed correctly to begin with but the new customer wants to be like all his bullhauling buddies and went from 22.5 lo-pro to 24.5 full size just to be cool, but didn't realize he just screwed up his sweet-spot and now has low power complaints. Get low rolling restiance tires if possible. Make sure the hole in the hood meets up with the air filter housing ( marking paint on the rubber bellows and close and latch the hood) a good seal so it's not sucking hot air off of the engine in the summertime. Some of those aftermarket chrome hood louvers restrict to much air on the higher HP engine( says on the package). And of course dont be running 80+ MPH, keep it as slow as you can sainly deal with. Some guys say changing the governer setting (in the ECM) to all-speed instead of min-max helps the MPG and I have seen it help once but the guy was already a slow and steady driver so not totally sure on that one. Thats all I can think of for now but I'm sure I'm leaving somethings out.

Didn't see that, what about over-tourqued injector hold downs, I have seen guys tighten them with a impact gun and collapse the injector body and they wont spray right? But I guess that would happen right after engine start up.

Haven't seen to many 2004 and up AC ASET EGR engines that get any better than 6.2 mpg. I am working with one guy and we got him at the 6.0 point, just added a high flow Walker muffler and waiting to see the results. There is not just one thing that makes a truck get good MPG it's a combination of many different things that get you there.

Check the air compressor air intake tube that run around the back of the engine to the back of the intake manifold, the short rubber hose could have blown off, it happened to me.

Duralit is the way to go but for small leaks like you had we have some epoxy we use that works good. But if you got the money go ahead and do the Duralite and be done with it.

I vote leaky liners especially if the engine had no coolant filter on it!

It is possible (sometimes)to unplug the speedometer sensor and the truck will run wide open MPH, however most owners/companys who have their road speeds turned down have the MPH sensor tamper settings enabled. What this means is if you unplug the sensor/tamper with the adjustment or any fault occurs with the MPH sensor it will derate the HP and you will be worse off than just leaving it alone.

Thanks!