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Mack truck e7 CX613 2001 low boost intermittent.


Ali Carmona

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hello, I have a Mack CX613 2001 with e7 engine, the truck has problems of boost preasure, sometimes it works normally with 30psi or more, but most of the time the pressure drops between 25-20psi, we already check the turbo and it is in perfect condition, change the joints of the turbo pipes, change the metal hose that goes from the air compressor and passes behind the engine, every time we do something it improves a little, but after 2 days of being operating, the psi again go down to 20-25psi, plus it is remarkable the lack of power when this happens, plus I noticed that sometimes the engine shuts down when I go on the road and I have to stop, remove the ignition key and when I try to turn it on, it lights without any problem, but the symptoms of low boost are not solved, also is good to mention that the pressure of the oil is also in between 40-50psi when operating temperature, the engine is getting worst really slowly but gradually if someone knows the reason of these problems and why they are generated, I would be grateful to guide me in what I can do to solve the problem. Thank you.

 

 

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You got a regular ETECH 460 engine, not a CCRS 460 which is good in this case. Late 2001-2003 were CCRS ETECH engines. These were improved versions of the engine you have now. The ones that were 460 HP had a waste gate turbo that’s caused lots of boost pressure issues. Lucky you don’t have that engine. The engine you do have is known for cracked and leaking intake manifold gaskets . They now make steel core gaskets that correct this. Yours really sounds like there might be some electrical issues though. Is the red X or yellow lighting bolt come on the dash when the issue occurs? 

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So You need to find out why its on now See if there are any related engine codes causing a de rate ! also I  don't know what kind of work u do However looking a the pic  just an observation the turbo appears to have been getting a bit warm indicating a boost leak  a split in the after cooler or gaskets as Pro Mentioned! U may have repaired this issue with the things you have already done! You need to see what codes it has logged that MAY reveal more !I agree with Pro It could indeed be a wire issue! 

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No I haven’t done them yet, I’m just wondering I don’t have to much time in this business and I have many questions yet, and I just want to be prevented because there was a mechanic who told me that maybe I’ll need a rebuild so I don’t know if he wants to get my money or if he is serious. But thanks very much for your advices.


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10 hours ago, Ali Carmona said:

No I haven’t done them yet, I’m just wondering I don’t have to much time in this business and I have many questions yet, and I just want to be prevented because there was a mechanic who told me that maybe I’ll need a rebuild so I don’t know if he wants to get my money or if he is serious. But thanks very much for your advices.


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If he hasn't pulled you're engine codes and told you what they are he's a dipshit. 

Go to the truck, turn key on, don't start engine. If lightning bolt stays on,  you have an Active Fault code. With cruise control off, hold down set/decel button for 3 seconds. Lightning bolt will blink a 2 digit number to you. Write it down. Each set/decel triggers computer to give you one code, if there's multiple active fault codes you need to hold set/decel again to draw the next code. Keep pulling codes til you've gotten all of them. 

Post codes here, I have a Mack manual that lists all the codes.

If one of the codes is serious the eecu will limit power to prevent serious damage to the engine. Could be a simple sensor failing. 

An engine rebuild doesn't fix electronic problems, it just fixes the mechanicals, which might be perfectly fine. Don't throw money at a problem you haven't diagnosed.

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2-1 engine coolant temperature sensor

4-2 fan clutch output

2-5 front drive axle oil temperature sensor

2-6 rear drive axle oil temperature sensor

2-4 transmission oil temperature sensor

3-1 exhaust temperature sensor

1-4 ambient air temperature sensor

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Go to your Mack dealer and order V-MAC III Service Manual #8-211 and ETECH Engine Service Manual #5-106

8-211 has all the blink codes, the procedure to get codes, and how to diagnose the code fault. 

5-106 has all the mechanical information on the engine, including sensor locations. Great intro section in it to give you how the computer runs everything.

If it were my truck, I'd use the books to go through and change all those sensors. 4-2 is possibly a faulty Fan Clutch Solenoid.

You should have some fun with knocking out those codes, I'll bet that faulty exhaust temp sensor and the ambient air sensor is your boost problem. Failing sensors are telling the computer the EGT are hotter than they really are, and so the computer is cutting back on the throttle.

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Don't need to. They'll become inactive faults, and the light will go off. Light only comes on for Active faults. Sensors tweak the voltage on the circuit, which the computer uses to determine what's going on. It throws a fault code when the voltage in a circuit goes outside the programmed voltage range. When voltage comes back into the proper range, the active fault is no longer present, so the light will turn off. Assuming there's no other active faults.

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Hopefully the problem is the sensors and not the wiring harness going bad. Vmac III book tells how to test the circuits to determine where the problem is, wiring or sensor.  Sensors are easy to replace, that's where I'd start.

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