SDP acert converted to 6nz, low power, low boost

Discussion in 'Trucks [ Eighteen Wheelers ]' started by maggard359, May 5, 2014.

  1. maggard359

    maggard359 Medium Load Member

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    I have a SDP acert I have swapped over to 6nz specs needing some guidance hopefully from someone who has conquered the task already. Start off it was a 2008 SDP with 500,000 miles. Bought truck with rocker bolts broken out of head from a guy who couldn't pay the repair bill. I changed rockers, injectors (0957's), wiring harness, ecm, spacer plate, single waste gated turbo, drilled hole for camshaft sensor behind air compressor like 6nz, put a 6nz camgear on it, took all the dpf and other emissions garbage off. swapped pins 11 and 21 for fan. Calibrated timing, started truck and it ran smooth no miss. Took it down the road for a test drive could only build 5lbs boost. low throttle response, low power. Back to the tree I went, done pressure check on all CAC, turbo, and boots. No leaks found. Checked fuel pressure range between 75 and 100 depending on throttle. Swapped boost sensor, atmospheric sensor, changed both regulators in fuel filter housing. Done all of this one at a time and test drove again with no changes. Changed injectors for a known set of good injectors, truck now makes 10lbs of boost, still seems weak. Never had trailer hooked to truck. Swapped throttle pedal, no change. Could the cam be the problem, I am out of ideas. It acts like injectors are too tight or something. No check engine lights period. Has anyone done the swap tell me maybe if they changed cam or not. The SDP's have a different style injector than the BXS's and Mxs. I am trying to figure out if the lobe on the cam is off causing my problems with proper injection?
     
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  3. GP1500SC

    GP1500SC Light Load Member

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    Yes.
    The injector lobe is the problem you will have to run a 6nz cam, or acert injector, the rate of plung is to slow to put enough fuel in.
     
  4. maggard359

    maggard359 Medium Load Member

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    Changed injectors today for the 58's. Made no difference period in performance. Boost still hanging at 10psi. Thanks for the advice on the cam GP1500, I am not convinced the cam is the entire problem. I am going to get a cam tomorrow, ugh I am not looking forward to this project. I just would have thought if it were only the cam causing me low power and low boost that going from the 57 injector to the 58 would have offered some extra boost giving more flow from the 58's?
     
  5. little cat 500

    little cat 500 Road Train Member

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    sounds more like a ecm problem
     
  6. maggard359

    maggard359 Medium Load Member

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    I bought ecm off a running motor with a thrown rod, had it uploaded with 550 brakesaver file. I can take boost sensor loose from head leave it plugged up and supply air to sensor, mash the throttle and not a bit of black smoke. I always get heavy black smoke when I run that test. You could be on to something, I hate to even think about asking Peterbilt or Cat to hookup and do a road test considering the Frankenstein condition its in.
     
  7. little cat 500

    little cat 500 Road Train Member

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    i know you cant run a accert cam in a 6nz
     
  8. maggard359

    maggard359 Medium Load Member

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    We have a bxs running 6nz box and single turbo with same cam. Another guy down the road swapped a Msx over to 6nz left cam and twins but changed ecm, wiring, and cam gear. I agree my cam will need changed in the sdp it was worth a shot to try since I have personally seen ....and been passed....by the other acerts hehe. We haul heavy and the way this truck pulls no I doubt it would even pull a hill with a wagon behind it. Im not arguing the cam point I am certain it is a problem, I just don't think its my only problem. The cam lobes don't know what injector a motor is running. My questions is what else am I missing, putting the hotter injector in should have gained some kind of performance increase weather it be more takeoff or even 1lb or 2 of boost. The cam would have squirted more fuel with the 58's than the 57's in my mind to offered a difference somewhere unless I have a restriction or some kind of ecm problem.
     
  9. little cat 500

    little cat 500 Road Train Member

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    should have seen some kinda increase from 57's to 58's
     
  10. maggard359

    maggard359 Medium Load Member

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    Truck idles smooth and drives and accelerates smooth. You can top out at 2100rpms in lower gears but the last two I am lucky to get 1600. The Msx in the other truck with a load of coal could outpull me bobtailing right now.
     
  11. little cat 500

    little cat 500 Road Train Member

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    with that said sounds more like a fuel problem
     
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