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2005 mack aset low power.


Dar
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Hi guys. I have a 2005 mack vision with an aset engine, been running it on the farm for a couple years. Always thought it was a bit low on power and boost was a bit high but it worked so I just kept driving. This fall however on my way home one night I could not get up to 60mph on the highway. Since then I can only get up to highway speed empty and even then the boost is continually 25-30 psi. Loaded I cannot get up to highway speed and boost rises as high as 33ish psi. There are a few codes present.

9-5.  Compressor discharge temp sensor

2-5. Front drive axle temp 

2-6. Rear drive axle temp

3-1. Exhaust temp sensor

All these codes were present before this new problem came up. Truck is fully serviced including new air filter and fuel filter. As soon as I get to town I will pick up some fittings so I can check the fuel pressure after the fuel lift pump. Also have a sensor coming for the turbo discharge temp code. If you have any suggestions I would be happy to hear. Thanks. 

I was reading a post from a few years ago of about an 03 model with what seems to be very similar problems. 

Screenshot_20200109-145847_Samsung Internet.jpg

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You can download the v-mac III service manual here.

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=6156

Just click the view file hyperlink and it will download, at the end of the manual you will see troubleshooting steps for your codes. As for lack of power i dont have much experience on what may be the issue but anything sensor related can be found in the manual.

Edited by ivanuke
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1 hour ago, Dar said:

Hi guys. I have a 2005 mack vision with an aset engine, been running it on the farm for a couple years. Always thought it was a bit low on power and boost was a bit high but it worked so I just kept driving. This fall however on my way home one night I could not get up to 60mph on the highway. Since then I can only get up to highway speed empty and even then the boost is continually 25-30 psi. Loaded I cannot get up to highway speed and boost rises as high as 33ish psi. There are a few codes present.

9-5.  Compressor discharge temp sensor

2-5. Front drive axle temp 

2-6. Rear drive axle temp

3-1. Exhaust temp sensor

All these codes were present before this new problem came up. Truck is fully serviced including new air filter and fuel filter. As soon as I get to town I will pick up some fittings so I can check the fuel pressure after the fuel lift pump. Also have a sensor coming for the turbo discharge temp code. If you have any suggestions I would be happy to hear. Thanks. 

I was reading a post from a few years ago of about an 03 model with what seems to be very similar problems. 

Screenshot_20200109-145847_Samsung Internet.jpg

Compressor discharge temp indicates the hood to air cleaner boot is not sealing sucking in engine compartment heat!!!!!! Fix the boot And see what happens!

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Replaced the fan clutch. Also replaced the visible damaged turbo discharge temp sensor. Code did not go away. Does it need to be cleared with a scan tool?  Still have no power. However it is also throwing #2pump code at cold start ups. When it warms up code goes away. Will wait till the fuel tanks get emptier and hopefully drain them. 

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9 hours ago, Dar said:

Replaced the fan clutch. Also replaced the visible damaged turbo discharge temp sensor. Code did not go away. Does it need to be cleared with a scan tool?  Still have no power. However it is also throwing #2pump code at cold start ups. When it warms up code goes away. Will wait till the fuel tanks get emptier and hopefully drain them. 

Which code is still active besides the pump code ?  Did you confirm the boot is sealing to the hood? 270 code is related to this!

Just sayin!

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Yes the boot is sealing to the hood. Besides the pump code when it's cold out I still have the 9-5 code for compressor discharge temp. And 3-1 code for exhaust gas temp. As well as codes for front and rear drive axle temp, obviously not concerned about those codes.  As nice as it would be to get rid of these codes I dont think they are the problem here due to the fact that they have all been active for 2 years prior to this problem. 

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10 hours ago, Dar said:

Yes the boot is sealing to the hood. Besides the pump code when it's cold out I still have the 9-5 code for compressor discharge temp. And 3-1 code for exhaust gas temp. As well as codes for front and rear drive axle temp, obviously not concerned about those codes.  As nice as it would be to get rid of these codes I dont think they are the problem here due to the fact that they have all been active for 2 years prior to this problem. 

Are you loosing any coolant ? any signs of coolant at the EGR cooler outlet?

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Not loosing any coolant. Checked fuel pressure today after the filter and pump and pressure would not dip below 60psi under load. The #2 pump code remains on all the time now and when I rev the engine to 1800 under no load I can hear the engine start to miss. Think the next step will be to change that fuel pump. 

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  • 2 months later...

Update. Had truck at the shop. They scanned and cleared codes. 9-5 code went away and has not returned. They also checked and pressurized intake system for leaks, checked turbo and actuator operation, and calibrated. Turbo boost is good. Checked fuel pressure. Checked for exhaust restriction. Checked throttle operation.  Performed cylinder balance test. They also scanned truck while driving in low power conditions and could not find anything wrong.  Everything checks out good. Cannot make the truck smoke in any condition. Still has codes for front and rear axle temperature sensors. And a 3-1 code.  Any chance the 3-1 code could cause a derate? Any other ideas? I dont know what to do with this thing. Already bought another truck to get by. But would still like to get it fixed. 

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So I'm going to throu this out there, If you have a mack trans and you a missing approx half your boost check the torque limit switch at the rear of the trans!  if it malfunctions the Vecu will derate with no code as it does not see any malfunction !IT Thinks everything's is AOK!

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On 4/7/2020 at 8:13 PM, Dar said:

Update. Had truck at the shop. They scanned and cleared codes. 9-5 code went away and has not returned. They also checked and pressurized intake system for leaks, checked turbo and actuator operation, and calibrated. Turbo boost is good. Checked fuel pressure. Checked for exhaust restriction. Checked throttle operation.  Performed cylinder balance test. They also scanned truck while driving in low power conditions and could not find anything wrong.  Everything checks out good. Cannot make the truck smoke in any condition. Still has codes for front and rear axle temperature sensors. And a 3-1 code.  Any chance the 3-1 code could cause a derate? Any other ideas? I dont know what to do with this thing. Already bought another truck to get by. But would still like to get it fixed. 

Don’t think the 3-1 pyrometer code would cause a derate, still would fix it to create a clean slate. You have a dyno in the neighborhood, I’d try to run it on to see what you have? 

Edited by Mack Technician
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I'm sure I could find a dyno within an hour or 2 from here. However I dont think there would be any point to running it on a dyno. I know its low on power. When I'm up to Weight and conditions are not perfect I can't even make it up to 60mph. If I do get up to speed she is giving it all she has just to keep it there. I wouldn't dare try to pass someone on the highway if they were going 90 cause it would take a mile to get passed them.

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