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Mackpro

Pedigreed Bulldog
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Posts posted by Mackpro

  1. There were some bad "out of the box " 7th injectors out there, The dealer should have caught it as there was a notice about checking the date code/serial number on one befor you install it. A sticking EGR valve will cause the DPF to fill up to fast and well as the EGR Diff sensor being bad and telling the EGR to stay open to much. We are also seeing DPF diff sensors giving false reading and telling the ECM that the DPF is full.

  2. Unless it's missing all the time, For an injector code with an FMI-8 we just replace the harness end. Be careful as the harness will be brittle and the insulation will break off. I have put alot of these on over years. Mack says replace all ends but if the harness is brittle and coming apart when you touch it, I usually just replace the bad one. But its up to the customer if he wants to risk damaging the harness to replace all ends. My friends MP-8 has almost 800000 miles on it with orignal harness and I have replaced 2 ends on 2 different ocassions. His truck runs fine but his harness is about toasted. In his case he would rather be down a couple hours 2 times versus having a new engine harness installed taking at least a day or more( depending on who installs it). The injector harness and the rest of the engine harness is all one piece.

    injector harness.pdf

  3. If you ever had to deal with Meritor warranty from a dealer standpoint, you would wish they never existed. The only time in my life where I made time to sit down and write a nasty letter to a corporation. That was about 8 years ago and I still hate them and things had not gotten much better. When my friends or close customers are specing a new truck I always make sure to steer them away from any Meritor items. May a thousand internet curses be upon them!

  4. We get alot of new broke down MRU's towed to our shop. They are usually being delivered to the customer from the bed companies. I have seen a couple of MRU's with what looked like HD headlights. Never really paid enough attention to check them out. We also had a new GU rawhide show truck , on its way to a big show and it had some weird blue bulbs in it. However I have never seen a CHU with any aftermarket lighting.

  5. On the poor throttle responce between gears, have you had the dealer do the "Step 12B" update to calibrate the throttle pedal? It seems to do wonders on some trucks. Just did one on a CXN this morning. Took me about 2 hr to reflash and download both ECM's. But with just a AMI-300 engine its just not much to work with. You could jump to a AMI-335 with just a download( HP upgrade) and it would give you 140 more FT LBS of torque. I dont know how much the download would cost as it has to be turned on at Mack and installed by the dealer. Also if these are MR or LE garbage trucks your limited to HP because of lack of radiator cooling.

  6. All AI and AMI engines seem to have high soot in the oil, mainly due to the design of the engine. The AI/AMI has 2 humps on the exhaust lobe of the camshaft and opens the exhaust valve twice. It will suck dirty exhaust out of the exhaust manifold (anyone notice how small the exhaust manifold is on a AI) and reburns it on the next stroke. Kinda like a EGR system. Thats how the AI/AMI got away with no EGR valve/cooler but the AC engine didnt. Also there are 3 or 4 ways of oil sampling. I know that the one the local CAT dealer uses always shows super high soot in the AI/AMI engines.

    oil sample.pdf

  7. Also check this as well, remove the black metal kick panel in front of the passenger seat. On the back of the kick plate will be the ABS ECM and the vehicle ECM. Make sure the vehicle ECM is facing down ( connectors facing down). If not unplug the 3 connectors and check for rotting/green pins. Also check the wiring harness for rubbing on the kick panel. We had alot of RD ETECH's with the ECM's facing up and full of water.

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