kgtruck13 Posted January 7, 2020 Share Posted January 7, 2020 370 ami non egr. Intermittent loss of power. No codes, fuel pressure 70-80 under load. Boost 30 plus. Watching fuel rate 19.5 mph than drops to 12 and engine loses power until it jumps back up to 19. Feels like a 2 stroke when it hits the power band. Trans is an 8LL Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted January 7, 2020 Share Posted January 7, 2020 (edited) 370AMI internal EGR. Easy fix if you want the throttle response (dead spot) fixed..... take it a little further and you'll have a decent truck. Click on.... Edited January 7, 2020 by Mack Technician 1 Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 8, 2020 Author Share Posted January 8, 2020 It's not a dead spot or slow response. I can have my foot in it at 100% and watching the fuel rate it's at 19 then all of a sudden it drops to 12 and you can feel the power loss. Keep the throttle in the same position and it will climb back to 19.you can watch it on the screen and the throttle percent never changes. Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted January 8, 2020 Share Posted January 8, 2020 Yup, lasts about 3-5 seconds. Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 8, 2020 Author Share Posted January 8, 2020 This just started sometimes it won't recover for awhile. You could pull a hill and it might stay down at 12 . Is it still the 12b flash file that is needed. The truck was fine before this started happening. Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted January 8, 2020 Share Posted January 8, 2020 It’s a symptom, check the software level. I’ve leaned on Mackpro in the past. He can usually tell what you have. 1 Quote Link to comment Share on other sites More sharing options...
fjh Posted January 8, 2020 Share Posted January 8, 2020 11 hours ago, Mack Technician said: It’s a symptom, check the software level. I’ve leaned on Mackpro in the past. He can usually tell what you have. Yup He's the MAN! Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 8, 2020 Author Share Posted January 8, 2020 Ok the last six are 007215 CT 713 Quote Link to comment Share on other sites More sharing options...
OldRedMack Posted January 9, 2020 Share Posted January 9, 2020 I would recommend pressure checking the intake and also unplug ecm and check for corrosion. Plastic coolant tanks are prone to cracking and leaking on ecm. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted January 9, 2020 Share Posted January 9, 2020 You truck is at the Step 12A level and that’s the way it came from the factory. Step 12 B download wouldn’t hurt it at all. I would start battery and ground connections . Start at the battery, then starter and aux starter solenoid and ground breaker on the fire wall next to the wiper motor, this is where power and ground come into the cab. Then pull the kick panel down in front of the passenger seat , carefully go over all the wiring going to the VECU and ABS ECM’s. Spend no less than 15 min looking at this area. Look for the paint rubbed off the firewall and kick panel where the wires lay against it . Very common to have bare wires shorting there that won’t set a fault code. Then carefully pull the 2 engine ECM connectors and look for coolant or oil and corrosion from leaking sensors . Also check for broken baffles in the muffler that can randomly clog the exhaust flow. Lastly , if the engine has a powerleash engine brake, pull the valve covers abs check the rocker arm hold down bolts and make sure none are broken . There is a service bulletin that’s posted here somewhere that discusses this , it leads to broken rocker arm shafts that actually lets oil into the engine brake oil passages and causes the brake to come on randomly. That’s all I can think of for now 1 Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 9, 2020 Author Share Posted January 9, 2020 I pressure checked charge air system. Checked grounds at starter and fixed bad connection on frame. Pulled both connectors on EECU no coolant or oil. Just came back from road test when it derate fuel rate. fuel pressure starts fluctuating violently between 60 and 80 psi. When it's not derating its steady. I changed the boost sensor and intake temp sensor also. Could EUP o rings cause this. I used a bubble gauge on lift pump outlet at idle and wide open no bubbles but not under load. Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 9, 2020 Author Share Posted January 9, 2020 If the gear slipped would it recover the way it does.its steady at 70 at idle and goes up as rpm increases.never goes over 80 psi. Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 9, 2020 Author Share Posted January 9, 2020 Let me try to clarify. It doesn't miss or sound like the engine brake comes on. The fuel rate goes from 19.... to 10 to 12 and thats when i noticed the fuel pressure on the mechanical gauge jumping back and forth. I have the gauge fastened to the wiper and boost gauge on the other wiper. When your accelerating or cruising it stays steady. Then when it acts up It flucuates when the fuel rate drops and your throttle pedal was never moved. If you let up on off on the pedal and back on it will start climbing like normal. Also I'm watching the percent value on the pedal and that stays consistent in the location of your foot. 50 75 100 etc... i hope this helps Quote Link to comment Share on other sites More sharing options...
kgtruck13 Posted January 10, 2020 Author Share Posted January 10, 2020 Found communication wire rubbed through seeing copper. Fixed it and left panel on floor with vecu. Test drove same result. Did notice when engine load dropped thats when the problem occurs. It goes from 100% to 70% and cuts the fuel rate back. When it jumps back up to 100 i get the fuel rate and power back. Hope this helps to help me fix this problem thanks. Quote Link to comment Share on other sites More sharing options...
86dm685s Posted December 30, 2020 Share Posted December 30, 2020 Hey did you ever find out what the problem was? My truck is doing the same thing. Losing power from 14-1600 rpm Under load ! Quote Link to comment Share on other sites More sharing options...
Vmac3 Posted January 22, 2021 Share Posted January 22, 2021 These AMI engines have software updates that corrected these issues. I have replaced the throttle pedal on some and it corrected the problem. I would try and monitor this while in cruise control. This will eliminate the throttle pedal circuit. Also a slipping gear on the fuel pump will cause this issue. As mentioned earlier, I would update the EECU and the VECU to the latest and greatest software and datafiles. Also try switching the governor settings from min-max to all speed or visa versa. V Quote Link to comment Share on other sites More sharing options...
petehall12 Posted October 8, 2023 Share Posted October 8, 2023 On 1/10/2020 at 12:27 PM, kgtruck13 said: Found communication wire rubbed through seeing copper. Fixed it and left panel on floor with vecu. Test drove same result. Did notice when engine load dropped thats when the problem occurs. It goes from 100% to 70% and cuts the fuel rate back. When it jumps back up to 100 i get the fuel rate and power back. Hope this helps to help me fix this problem thanks. Did you ever figure out how to fix this problem Quote Link to comment Share on other sites More sharing options...
petehall12 Posted October 8, 2023 Share Posted October 8, 2023 Myne does something similar as well it will be pulling making 30 pounds of boost and then all the sudden it’s like you take your foot half way off the throttle. The truck will stop pulling and the boost gauge will fall back to 18-20 pounds sit there for about 5 seconds then jump right back to 30 pounds and go back to pulling. I have been trying to figure it out and it is aggravating as hell. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted October 8, 2023 Share Posted October 8, 2023 What model truck do you have? That post is 2 years old. You may want to start your own thread.. If you have an ASET-C, check the part number on the boost sensor against the VIN.. they operate on 5 volts and 1/2 of a volt difference will cause issues. The part number is printed into the flats on the sensor.. Quote Link to comment Share on other sites More sharing options...
petehall12 Posted October 8, 2023 Share Posted October 8, 2023 (edited) 4 hours ago, Joey Mack said: What model truck do you have? That post is 2 years old. You may want to start your own thread.. If you have an ASET-C, check the part number on the boost sensor against the VIN.. they operate on 5 volts and 1/2 of a volt difference will cause issues. The part number is printed into the flats on the sensor.. I have a 2004 ami370 was hoping he found a solution Edited October 8, 2023 by petehall12 Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 8, 2023 Share Posted October 8, 2023 (edited) Start with checking the engine software level at the dealer, the "12b" update should correct much of your issues. If not then give this a thorough read.... https://www.bigmacktrucks.com/topic/50251-mack-ai460-ai427-ami-low-torque-low-horsepower-poor-fuel-mileage-granite-dead-dog-remediation/ Edited October 8, 2023 by JoeH Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted October 8, 2023 Share Posted October 8, 2023 I just realized that you have a couple threads about this truck.. I will study them again and see if I can think of anything else, and wait for you to work on the other suggestions, and post the results.. I am not a huge fan of ASET's, but the one you have is the better one, and with proper tuning and valve adjustment, it is reliable.. ( without trying to make an obvious statement) Jojo Quote Link to comment Share on other sites More sharing options...
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