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New to this site. Have a 2008 mack with the mp8 engine. Seems low on power compared to my pld 1990 400. Have had local dealer do turbo update and try to diagnose lightning bolt indicator. They cannot find problem. Truck has 60000 km on it now and otherwise seems fine. Does anyone have any suggestions?

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New to this site. Have a 2008 mack with the mp8 engine. Seems low on power compared to my pld 1990 400. Have had local dealer do turbo update and try to diagnose lightning bolt indicator. They cannot find problem. Truck has 60000 km on it now and otherwise seems fine. Does anyone have any suggestions?

What horsepower is it? Any additional symptoms, such as hard starting? Does your truck have the VIP screen with the stalk switch? If so cycle through to the diagnostics screen and get the active and inactive fault code numbers and post them. There should be an MID number, a PID, PSID, or PPID and a FMI number for each fault. Most of the MP8 engines I have seen are 485 hp, the lowest rating for the MP8 with US07 emissions is 415 hp. The most common problem with these engines has been leaking injector cups. There are revised parts now available to repair this problem.

"Mebbe I'm too ugly and stupid to give up!"

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What horsepower is it? Any additional symptoms, such as hard starting? Does your truck have the VIP screen with the stalk switch? If so cycle through to the diagnostics screen and get the active and inactive fault code numbers and post them. There should be an MID number, a PID, PSID, or PPID and a FMI number for each fault. Most of the MP8 engines I have seen are 485 hp, the lowest rating for the MP8 with US07 emissions is 415 hp. The most common problem with these engines has been leaking injector cups. There are revised parts now available to repair this problem.

The horsepower is 485. It has always started fine and other than poor pulling has ran fine. I do have the VIP screen and habe the fault codes. Proor to che3cking the screen I removed the bat cables, checked and replaced cab fuse 13 abs engine circuit protector f49 -abs, they were missing. Turned all back on and now have the yellow ATC on steady with no flashes. The active codes now are ABS mid 136, SID 89, FMI 9. I suspect I may have a problem with ABS or traction control. Will ths derate the engine, and how do I tell when the injector cups are done? I.m the second owner but think that warranty may cover.

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The horsepower is 485. It has always started fine and other than poor pulling has ran fine. I do have the VIP screen and habe the fault codes. Proor to che3cking the screen I removed the bat cables, checked and replaced cab fuse 13 abs engine circuit protector f49 -abs, they were missing. Turned all back on and now have the yellow ATC on steady with no flashes. The active codes now are ABS mid 136, SID 89, FMI 9. I suspect I may have a problem with ABS or traction control. Will ths derate the engine, and how do I tell when the injector cups are done? I.m the second owner but think that warranty may cover.

ABS can derate the engine if a discrepancy is seen between wheel speed at the ABS sensors and at the road speed sensor. There is a programmable parameter that can be turned off. I forget the parameter ID at the moment, but its described as tamper detection. You will most likely have to take it to a dealership to have this parameter changed, unless you have Mack's software program. While you're there have them check the warranty history on the engine to see if the cups have been replaced, but my guess is that you don't have the most current parts installed as they were only made available in the last month or so.

"Mebbe I'm too ugly and stupid to give up!"

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ABS can derate the engine if a discrepancy is seen between wheel speed at the ABS sensors and at the road speed sensor. There is a programmable parameter that can be turned off. I forget the parameter ID at the moment, but its described as tamper detection. You will most likely have to take it to a dealership to have this parameter changed, unless you have Mack's software program. While you're there have them check the warranty history on the engine to see if the cups have been replaced, but my guess is that you don't have the most current parts installed as they were only made available in the last month or so.

I will have to take it to dealer. Would 60,000 km do in the orig injector cups? What should i notice if they are the culprit. If in fact the abs or traction control is derating what would be the change in horsepower? It feels like about 125 hp short in my mind. The dealer had a third party dyno test done during my last viait with 385 rear wheel hp being "their results". I just wanna make sure im headin down the right trail. One thing i do know is that dropping the air bags while travelling derates to the point where you cant push the wind. If this is derate ive got something else wrong.

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I will have to take it to dealer. Would 60,000 km do in the orig injector cups? What should i notice if they are the culprit. If in fact the abs or traction control is derating what would be the change in horsepower? It feels like about 125 hp short in my mind. The dealer had a third party dyno test done during my last viait with 385 rear wheel hp being "their results". I just wanna make sure im headin down the right trail. One thing i do know is that dropping the air bags while travelling derates to the point where you cant push the wind. If this is derate ive got something else wrong.

I can't remember for sure on VMAC IV, but the percent of derate for vehicle speed fault is programmable in VMAC III. The injector cups can go at any time really. Some seem to go within the first 3-4 months and some last for a year or so. Usually the engine is hard to start when the cups go bad, if given enough time. When there is only one that is leaking slightly there may be no really noticable syptoms at all. You might see M128 S1-6 injecctor codes or M128 P94 fuel pressure codes, among others. Was the code you posted the only code? Make sure there were no other codes in the active and in the inactive screens for each MID.

"Mebbe I'm too ugly and stupid to give up!"

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I can't remember for sure on VMAC IV, but the percent of derate for vehicle speed fault is programmable in VMAC III. The injector cups can go at any time really. Some seem to go within the first 3-4 months and some last for a year or so. Usually the engine is hard to start when the cups go bad, if given enough time. When there is only one that is leaking slightly there may be no really noticable syptoms at all. You might see M128 S1-6 injecctor codes or M128 P94 fuel pressure codes, among others. Was the code you posted the only code? Make sure there were no other codes in the active and in the inactive screens for each MID.

The posted code is the only current code. Since clearing codes and disconnecting batteries I have not used truck but I do recall seeing p94 fuel pres code a while back. It starts good and runs smooth etc. Im leaning towards poor or weak injectors. Thanks for the info, cant wait to see what dealer has to say, will let you know. Wonderin if I should get my own dyno test done b4 seeing dealer?

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The posted code is the only current code. Since clearing codes and disconnecting batteries I have not used truck but I do recall seeing p94 fuel pres code a while back. It starts good and runs smooth etc. Im leaning towards poor or weak injectors. Thanks for the info, cant wait to see what dealer has to say, will let you know. Wonderin if I should get my own dyno test done b4 seeing dealer?

The programmable parameters I refer to are DTS (speed sensor tamper detection), which can be either on or off, and DTW (speed sensor tamper detection torque limit), which can be set between 0 and 100% when a fault is noted in the speed sensor reading. There could possibly be a problem with the injector tips if they have been cleaned previously in an incorrect manner. The injector tips for theses engnes (MP series) are extremely touchy and can be damaged very easily if cleaned with wire brushes, etc. If the injector cups have been replaced before there is a good chance that the injectors could have been damaged at that time.

"Mebbe I'm too ugly and stupid to give up!"

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