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Weak E7-350


jswilliams

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I have a 97 ch613 with an e7-350 and it's very weak. Boost gauge only goes to 20 at the most and 90% of the time it only goes to 15. A little black smoke when I shift but nothing crazy. I have a blixxton box installed and it makes no difference what so ever. I pressure tested the charge air cooler and its fine I also bypassed the compressor intake hose by screwing it out and plugging the hole in the intake manifold. When I put air on the intake manifold I can barely get the pressure to 25 psi and it takes a while and as soon as I remove the air chuck it drops instantly. No air leaks can be found or heard and soapy water has been sprayed everywhere. Can it leak somewhere in the head and I not be able to tell? Also is there anything I can check to make it pull better? Also all of the filters are new. 

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I don't understand why I can't pump air into the system and only get up to 20-22 psi. After that it just stops climbing yet I can't hear or see any leaks. And I'm using a compressor capable of 27 cfm. I hook on the pipe coming off the turbo and pressurize the air cooler, intake manifold, and so on. Even bypassed the hose that goes around to the compressor to eliminate it. 

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If you pressure up to the heads try rotating the engine slow watching the pressure gauge.At some point there will be intake or exhaust valves closed on all cyl enough to pressure it up but rotate slow.I dont pressure more than 25psi on the heads because i think you couldblow the intake seals off with more pressure.

  • Like 1

glenn akers

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Just the info I needed. Thanks a lot. If I were to install larger injectors like the Rochester stage 2's  for example, do I have to take the truck to Mack to have the computer reprogrammed for it to have more power or does it just spray more fuel with the larger injectors? 

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The torque limit switch would be mounted on the range cyl at the back the switch near the stick is the reverse switch!If you have a huge boost leak you would be trailing smoke all the time and if you have a pyrometer the temps would climb fast!

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Oh ok so I probably don't have a boost leak bc Im not trailing any smoke. No Pyro installed yet. I looked at the fins on the turbo and they seem to have some buildup on them which may be causing the low boost issue. I'll try the torque limit switch and if that don't work I think I'm gonna install larger injectors and possibly a new turbo. 

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  • 4 years later...
On 10/11/2017 at 9:54 AM, fjh said:

The torque limit switch would be mounted on the range cyl at the back the switch near the stick is the reverse switch!If you have a huge boost leak you would be trailing smoke all the time and if you have a pyrometer the temps would climb fast!

 

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  • 2 weeks later...

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