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Thread: overboost, overboost not enabled

  1. #21
    Supporting Member Turbo Mopar Contributor
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    Re: overboost, overboost not enabled

    Quote Originally Posted by jeff1234 View Post
    who can explain the weirdness of these cars.?
    jeff
    I am unsure who can explain but here are my thoughts. First sensors are critical and second I feel the LM with its limited processing power is an issue. Yes the 8640 does help a bit with floating point math.
    I have read that once the LM gets in the 5000rpm range the processor can no longer effectively loop through its tasks.
    The mopar tech student manual chapter on speed density is quite interesting and everytime I real it, I learn more.
    MAP is #1 which is why a vacuum leak is so bad. TPS is #2, Coolant is #3 VSS is also high on the list.

    I have two 87 P bodies and I was concerned with the limited power of the LM. I will tell the story of my poor gas mileage but no codes no vacuum leaks. I received codes of HEP ref, sync and all sorts of different codes on different days but could not see a trend. One day during an overboost from my MBC, the CEL was on a bit longer than normal and went away. O2 sensor was a stored code and never returned. I thought let's replace the oxygen sensor anyway since it is old...Well it fixed my poor mileage but more surprisingly it stopped all the other unrelated codes The SMEC and SBEC both have a more powerful processors and also both more advanced aux processing units. It appears they are some sort of PLCD/FPGA/ASIC devices so they should be able to control the engine better at least in theory..
    As you may know, I work frequently with our ECU and all four of my LM have delaminating traces on the LM board. You can tell as the trace copper looks wavy or wrinkled. The rest of stash of SMEC/SBEC/SBEC2 pcb traces are like new condition and are of higher quality.Last winter I rewired the CSX to SBEC so we will see
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  2. #22
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: overboost, overboost not enabled

    if the staging limiter is turned on (cant remember if the initial setup was on or off) and the VSS is failing intermittently (code 15) then it will hit a rev limiter if the LM sees a 0 speed signal.

    the speed sensor connector is typically crap on the early cars too.

    even with the new sensor, the connector might be making intermittent connections.

    there was a recent thread on here (cant remember where it was) about converting to the later speed sensor which was more reliable.

    Brian

    - - - Updated - - -

    http://www.turbo-mopar.com/forums/sh...sensor-upgrade

    here it is.

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  3. #23
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Miles, I have created a wiring interface to run a smec but it blows a fuse on the fusable link circuit that controls dash and warning lights and ignition switch. I had replaced the fusable links with a fuse panel. I have checked out the wiring a number of times and everybody appears to be in the right place. I wonder if the instruction for the rewiring has a glitch in it. Anyway, i have issues to resolve before I revisit that.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  4. #24
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Brian. Are you saying that the original molded two pin plug on the VSS harness can have broken wires? That is interesting about the rev limiter I will check it out on mptune but that shouldn't affect the stock lm. In my case I can't use the rock auto kit because I have a cable driven mechanical speedometer.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  5. #25
    Supporting Member Turbo Mopar Contributor
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    Re: overboost, overboost not enabled

    Minimopar has a section on how to upgrade an old style VSS to the new style technology while still having the speedo connection. At that time you could upgrade to the new style electrical connector.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  6. #26
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Yes, i have been looking at that. I might try upgrading the one I took out.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  7. #27
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: overboost, overboost not enabled

    Quote Originally Posted by jeff1234 View Post
    Brian. Are you saying that the original molded two pin plug on the VSS harness can have broken wires? That is interesting about the rev limiter I will check it out on mptune but that shouldn't affect the stock lm. In my case I can't use the rock auto kit because I have a cable driven mechanical speedometer.

    maybe the wires.... but the connector pins get loose.

    i would make sure this setting is off as a test.

    Click image for larger version. 

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    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  8. #28
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Brian. The staging limiter was NOT checked. The FlashCE mod is. Should it be?
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  9. #29
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Brian. The staging limiter was NOT checked. The FlashCE mod is. Should it be?
    Also in power loss light mask coolant temp sensor is not checked. Should it be?
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  10. #30
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: overboost, overboost not enabled

    The FlashCE light box being checked will allow for the check engine light to come on when there is knock. I always enable that. If the coolant temp mask light is checked it will not illuminate the CEL, but it will store a code.

  11. #31
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    I think I may have figured out what is wrong. I think the diode for the map sensor may be to close to the 4.6 volt specification. If the diode is allowing the voltage to reach 4.6V wouldnt that cause this backfre problem?
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  12. #32
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    Re: overboost, overboost not enabled

    Quote Originally Posted by jeff1234 View Post
    I think I may have figured out what is wrong. I think the diode for the map sensor may be to close to the 4.6 volt specification. If the diode is allowing the voltage to reach 4.6V wouldnt that cause this backfre problem?
    Did you add this diode?
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    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  13. #33
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    I set up my diode as the instructions in The Dodge Garage tells us. All of my map sensors (Chrysler 2 bar and GM three bar) are set up that way. My map sensor is in the engine compartment near the shock tower.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  14. #34
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: overboost, overboost not enabled

    I'm lost. Jeff, are you running a Zeiner diode to the map to stop it from seeing above a certain voltage? If you're rolling your own cals, I don't understand that.

  15. #35
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Miles. I really don't see a symbol for a diode in that schematic, perhaps it is displayed in a form im not familiar with. I am not an ET.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  16. #36
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Cordes, that's a surprising response. What you seem to be saying is that I have made a mistake. Please correct me, I thought I was doing what I was supposed to. We may be on to the answet. What should I do?
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  17. #37
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Cordes. There must be more to this yet because at present I'm running stock tunes.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  18. #38
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: overboost, overboost not enabled

    Ditch the diode asap. Since you can see all the boost you're making with the three bar map, there is no need for it.

    Now, I still see a problem since you were having this problem with the 3bar map and you really shouldn't be getting any where near that voltage out of it at the boost I seem to recall you running. Regardless, it's one less thing to worry about being a cause. It's easy enough to swap the sensor and cal based off of the boost you're running anyway. For the purposes of testing, I would keep the boost as low as possible which will help to track down the root of this.

  19. #39
    Garrett booster
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    Re: overboost, overboost not enabled

    Jeff, did you add the diode just to prevent over-boost? If so I completely agree with cordes on removing the diode. I also don't think it's causing the problem, but the more the system can be simplified the faster you can find the root cause.

  20. #40
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: overboost, overboost not enabled

    Will do, thanks you guys, I had no idea.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

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