E7 low power help!

[Mackpro]

There is only a intake temp sensor ( 2 wires) on the VMAC 1 and VMAC 2 engines. A boost sensor would have 3 wires . The TEM sensor timing event sensor in the side of the pump. Make sure it’s gently screwed in till it bottoms out and gently tighten the jam nut. Lots of people either back the sensor out a half turn or crank down on the jam nut with a 2 foot long wrench and stretch the sensor and ruin it. Also the RPM sensor under the starter that goes into the bell housing. If it’s not adjusted correctly it will cause surging and missing at high RPMS . It to can be streched by over tightened jam nut .  Mack says back out the rpm sensor one turn but we usually do 3/4 turn . Also a ETECH flywheel will fit on your engine but cause the rpm sensor not to read . Seen that a bunch . 

[Dtech]

I am getting RPM on the scanner if I unplug the flywheel sensor I loose my tach and motor starts to run ruff. I also get a ruff white smoke if I unplug sensor on the injection pump. I noticed I have a sensor that seems to be missing wires on the back of the transmission. Did Mack have a torque derate if it was not in High Range? I think I ran into something along those lines before? 

[Joey Mack]

the sensor in the flywheel housing is called,, ''RPM/TDC sensor''........ your doin good..  jojo

[JoeH]

Not familiar with vmac ii, but an old endt676 we had had a 5th gear air valve on the transmission that'd allow the fuel rack to open up all the way

[Dtech]

Thanks yes, I found it and checked its clearance.  I was wondering if the computer is in a torque derate? I found a sensor on high range that looks like it had wires on it. The customer did pull the Transmission so he might have not reconnected this sensor?  I am asking about the wire E2 for the Torque limit switch is anyone familiar with this switch? It is possibly the switch in the picture above? I am going to check the wire at E2 to see if it is grounded. 

[Dtech]

Ok I am needing some help here I have a mac I system not a mac II ! so the above picture is not correct. According to the manual I should have a connection between pin 46 and 36 on the FIC plug when in low Range for the torque limit switch I do not, and do not have it in High Range also. I do have 13v on pin 46, and 9.8v on pin 36. with the key on I have 13v on pin 46, and 36 with the key off? I wonder if I have a bad FIC? I am also confused on the pin out chart, it labels pin 36 as Torque limit Plus + line and pin 46 as analog ground line. Anyone have any insight on this circuit ? Thanks Jeremy

[fjh]

So I need to ask what trans do you have and are there any codes coming up other the the inlet air ? If you have a 18 speed Tran s un plug the low range switch at the rear shift cylinder see if this changes things! If the wiring to this switch has rubbed together anywhere between the switch and the vecu it will de rate the power by 50 percent! This will not throw a code the computer will think this is normal!follow that trouble chart you have posted there if you can locate the two wires to the switch cut or remove them from the vecu plug this way the vecu will never see a closed switch!

[Dtech]

I have A t2180 for a Transmission, I do not have any active codes. This motor has low power just like it is at 50 % derate. The switch in the picture is what I believe Mack used as Torque limit switch. Do you know how the  torque limit circuit works ? Does it ground wire 36 in low range? Why do I have voltage on that wire and 46? I have mac II software but can not find a adapter that will communicate so I have no Idea if it is in a Torque limit state. I cut wire 36 so no chance of a false input, still has no power! The story I was given is that it ran well before the out of Frame overhaul. However I talked to a driver yesterday that told me this truck has always been under powered? I took off the eclectic part of the Injection pump governor and ran the Rack my hand! She Definity rolled some smoke then so I feel the pump can produce power.    

[fjh]

That is the switch the wire I’m not sure! Have you checked for boost leaks black smoke is a good sign! You got fuel! lack of air may be your issue! Air filter new? Check the turbo ! Check thectube at the compressor inlet and at the manifold left side for holes also by pass your air drier temporarily for something to try! They can dump boost as well!

[Dtech]

Yes I have checked for boost leaks, The black smoke is only when I was manually moving the Rack inside the fuel pump. Items I have checked so far Turbo, Intake, air filter, air compressor supply line, Air charge cooler, Fuel psi, exhaust restrictions, valve lash, Cam Timing, Injection timing, Tps, intake air temp sensor water temp sensor. The scanner shows it going to 100% load. I can only watch the following parameters oil psi, water temp, intake temp, tps, load, rpm, road speed, and voltage. Can anyone shine some light on the torque limit circuit for mac I, why would wire 36 be labeled positive and wire 46 be a ground? I also don't understand why the wires have voltage on them. 

[fjh]

1 hour ago, Dtech said:

Yes I have checked for boost leaks, The black smoke is only when I was manually moving the Rack inside the fuel pump. Items I have checked so far Turbo, Intake, air filter, air compressor supply line, Air charge cooler, Fuel psi, exhaust restrictions, valve lash, Cam Timing, Injection timing, Tps, intake air temp sensor water temp sensor. The scanner shows it going to 100% load. I can only watch the following parameters oil psi, water temp, intake temp, tps, load, rpm, road speed, and voltage. Can anyone shine some light on the torque limit circuit for mac I, why would wire 36 be labeled positive and wire 46 be a ground? I also don't understand why the wires have voltage on them. 

Bro!
So post the model and year of truck and last six of the vin there are guys on here that may be able to help either the vecu wiring set up . I no longer have access to this stuff ! There are a few here that may! I would think there would be voltage down one wire to that switch! And back to ground at the vecu! Does the power show up at the wire at the switch?at the transmission? If so a full 12v or .7

[Joey Mack]

I am struggling with this one...   You are using a scanner to look at a mechanical Mack E-7... you say it has low power and black smoke. you say that you checked all the turbo parts and piping..  checked the timing??  how did you check inj. pump timing?  This engine is one that you take for a test drive and feel the issue.  and its one that you can run in the shop and determine fuel issues..  I wish I was there to work with you as well as  a bunch of guys here would love to be there..   we used to just use gauges to find fueling issues.. of course, I dont know everything and never worked with modern computers for V-mac-I or II..  

[Dtech]

No black smoke, Only when I ran the pump rack manually. I did that test to prove the pump plungers fuel lift pump etc, are not the problem. This was done in the service bay not driven, but you could tell she was putting the fuel to it. When the truck is driven It will only build 5 to 7 psi of boost running down the road. No smoke engine feels like it is in the Torque limit derate.  I checked the timing by the book and by using a J-37077 timing tool. Its a 1995 E7 ch613 The complete vin is 1M2AA13YXSW058895. I found a old Prolink 9000 on eBay so I can hopefully watch the Torque limit parameter? Now as far as the Torque limit derate switch, no wires going to the switch that I can find. The wire pinout calls for wire 36 at the FIC as the signal wire for Torque limit derate. That wire has voltage on it with the key switched on 4.7 v. The wire it should be connected to pin 46 at the FIC is a ground. My understanding of the circuit is that it is Normally closed during low range pin 36 to 46. No active or inactive codes, the Diesel laptop scanner I am using right now shows' me that TPS is 100% and load is 100% during the test drives. It will not display the Torque limit parameter so I have no Idea if it is programmed for it or if it is in the active derate state. However completing the circuit pin 36 to 46 makes no difference in power.       

[mdixon]

Does it have the right injectors in it? Have you thermal gunned the exhaust ports? Dial indicator the rocker arms to check travel? Bent pushrods? 

Did you tie a light bulb between those two pins to simulate some resistance? Maybe pull that switch and apply air manually and see if that fixes the problem, although it might not be programmed in the ECU to begin with. If you got no boost and no smoke it's definitely pulling fuel, how does it pull in low range? Does it struggle at all? 

[doubleclutchinweasel]

I don’t know crap about this computerized stuff. But the OP’s question about the “unused sensor” and the question about the “derate” programming seem to deserve some thought. 
But, again, I don’t know s#!t about this one. 

[Dtech]

• 
• Puppy Poster
• •  94

Posted 14 hours ago

Does it have the right injectors in it? Have you thermal gunned the exhaust ports? Dial indicator the rocker arms to check travel? Bent pushrods? 

Did you tie a light bulb between those two pins to simulate some resistance? Maybe pull that switch and apply air manually and see if that fixes the problem, although it might not be programmed in the ECU to begin with. If you got no boost and no smoke it's definitely pulling fuel, how does it pull in low range? Does it struggle at all?  

 

The Injector nozzle's are reman, But again if the rack is ran Manually the Injection pump has no problem pouring the fuel to the motor. I did check travel on the cam lobs its with in speck in the manual, did Not find bent push tubs when I checked the valve Adjustment, It run low in power all the time even low range. only builds 5 to 7 psi boost psi. Not sure about your question on applying air to the switch manually? There are no wires going to it. The switch is NC in low range and No in high range. Thanks for your input the more heads we have thinking about it the quicker I can figure it out.

[mdixon]

If you use the pins you found in the book that that switch should be wired to and wire it up, then apply constant air pressure through a jumper air line and drive it. Or wire a light bulb in line with the switch and see if it's actuating when it's supposed to. 

How's fuel volume? Just because it's making pressure doesn't mean there isn't a restriction in the fuel lines somewhere, which would strangle the engine in all gears and not produce any smoke. Hard to say that smoke at idle pushing the rack is "good", there's no load in neutral.

 

 

Edited July 27, 2023 by mdixon

[Dtech]

I tried connecting a light and ran wires to the switch same result. My understanding of the Torque limit switch, is a closed circuit pin 36 and 46 on the FIC means to apply the Torque limit feature. I completely agree with you about running the rack with no load is not ruling out possible issues on the fuel side. However I can tell you she was Definity wanting to run lol. With out taking the pump off and having it flow tested I don't know how to check fuel volume. Do you know of a test on the truck? lift pump psi to the injection pump was at 27 psi when I was on the last test drive. 

[mdixon]

Pull the fuel supply and return off and run them into a 5gal bucket, full of clean fuel. Fuel rate at idle should be able to be found somewhere. Measure fuel after a predetermined amount of time. You can also try running a new fuel supply line and see if that fixes it. 

 

Something could be shorted internally in the ecm too, and thats a tough to find without dealer software or swapping ecms

[Dtech]

I am leaning towards the ecm as of Right now I should get the prolink 9000 Monday to hopefully watch The Torque limit value. I will keep you guys informed. 

[Joey Mack]

I'm impressed that you found a Pro Link 9000.. that's what I cut my teeth on back in 2000...  

[Dtech]

Joey Back in the day when we had green screens and  C : dos. computers lol. Can you change parameter's like the torque limit derate on an ecm with one? I am hoping it at least gives me more info to watch, 

[Joey Mack]

Buddy,  I have forgotten about all of it, but if I was there with it in my hand, I bet I could navigate it....  jojo

[Dtech]

Okay I finally got my old Prolink from E bay Can could watch the torque limit derate. It was not programmed for it and the switch is in the off position. Prolink did display 100 load and 100 throttle on the test drive fuel quantity went to 145 no valve given just a number I am not sure what this means maybe someone does? Travel of the fuel rack in mm? I am wondering about fuel nozzels the owner has no idea if they were changed I am trying to get a answer out of the mechanic that rebuilt the motor. Could a guy have installed nozzles that would cause this low of power? Can anyone confirm if 27 psi under load is a okay fuel psi. 

[Dtech]

We are back on this project today I have a Question for you E7 Mack experts. We checked the valve lash using the procedure in the book, however we noticed that when the intake valve is fully open on a cylinder the Exhaust valve on the same cylinder has lots of lash! This means that Mack does not adjust lash on the base circle of the camshaft lobe or we are out of time. Has anyone with experience ever noticed this? Just to be clear if I turn the Crankshaft in the direction of rotation to the cylinder marked on the flywheel 1-6, for example, that lash is correct however if I keep rotating it to the next set to be adjusted, the lash becomes larger than 0.024 around in the .060 thousandths on that previously adjusted exhaust valve? It will keep that gap through out the intake stroke and comes back to the .024 right before TDC on the compression stroke.  Is this normal? I also noted that this only happens on the Exhaust valve the intake lash remains the same through out all stokes other than the  intake stroke of course The mechanic that built this motor told me he had installed a used Crankshaft.  He had to change the Crankshaft drive gear due to size deference, the new use crankshaft had a larger gear on it !!! so he swapped it with the original drive gear.  I did check crankshaft to camshaft timing using the book procedure it seem to be on the money, I also did notice that Valve overlap is happening on TDC. I also double checked flywheel to crankshaft timing by pulling the nozzle on #1 cylinder and confirmed  TDC #1 alines with TC mark on flywheel.  Thanks For your help