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Thread: LE5 Turbo build - E67 ECM Dies at WOT

  1. #1
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    LE5 Turbo build - E67 ECM Dies at WOT

    Hi, I would like to clarify that I have no background in tuning, but have been playing with my LE5 for some time with HPTuners.

    This is an offroad car (that I mostly drive on the road) with most of the security, trans, VSS setting, etc. disabled.

    I have recently added a turbo at 14 psi, 60 lb Deka injectors and I have a boost controlled fuel pressure regulator with a return system set at 43.5 psi (with the vacuum line disconnected).

    I have a wideband in the car but not connected to HPTuners.

    Quite honestly, I am amazed that I have been able to produce a running motor.

    I can WOT and PE will hit about 11.5 AFR. I am positive that the timing needs help as I have some stutter and occasional backfire at WOT.

    All that aside, the most concerning issue that has occurred 3 times during this last few months is at WOT, the car goes LIMP and throttle pedal is DEAD - Motor runs but sounds really rough and no acceleration or control whatsoever. A Scan reveals MAP, MAF, TPS, Camshaft errors - Sorry I do not have the exact errors as it has been imperative in each occurrence to get up and running again.

    The motor will turn off and on, but no throttle and sounds like a bucket of bolts.

    I reflash the computer and all is fine!!!

    Today it happened in a pull from first gear at 6300 rpm in the final minute of the attached log.

    Has anyone experienced this? I suspected I maxed out my MAF but the log does not record that?

    This tune was basically built from a stock Cobalt SS 2.4.

    Thanks

    loswt computer at end.hpl
    Test saturn style timing hybrid.hpt
    Last edited by bajalobster; 08-09-2015 at 07:25 PM.

  2. #2
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    Have you messed with anyone of the electronic throttle tables? Your throttle % by the logs just seem like you have something going on there and the very low ignition timing. In the log that you have some pulls going on, were you 100% throttle the whole time or were you throttling it? The throttle goes from 88% which is 100% pedal and starts working its way down, is that you?

  3. #3
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    I have not altered the throttle tables. Also, just checked them against a stock tune in the repository for a 2007 chevy cobalt ss 2.4. My "zero" point is about 22 on the TPS and WOT is 88.

    Whatever decrease in TPS you see is probably me feathering back - at least prior to shifting. Keep in mind this is an offroad car and honestly WOT doesn't take long - you either have to shift or let off the throttle as 100 mph comes really fast and there is nowhere else to go.

    Today on the freeway I got these errors - similar to when the computer has failed in the past.

    PO 121 Throttle Pedal Position Sensor Circuit A Range
    PO 366 Camshaft Position Sensor B Circuit Range

    Thanks

  4. #4
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    I still think there might be something going on with throttle. Just how square wave the tps % is on the scanner. Did you do your own wiring? Definitely just check over the wiring to both throttle and camshaft sensor.

  5. #5
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    Harness is professional built. Interestingly enough I did find a potential "short" chaffed wire to the Exhaust Camshaft Solenoid Sensor. I fixed it but have no reason to believe that was the root of the problem. Keep in mind the 3 times that this has occurred it has been at WOT when I was seriously trying to hurt the car.

  6. #6
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    I took the car out on the freeway today - came down the ramp in 3rd gear, leveled out with traffic at about 60mph, found my opening, punched it and blew the computer out...

    limped to the side of the road stuttering and sputtering....no laptop, no scanning, planning for tow truck. Turned it off for about 20 seconds, and she started right up and ready to go. Took steady boost on the way home - It was definitely the PUNCH that tripped the circuits.

    When I got home I was able to scan the codes...

    P0068
    P0102
    P0121
    P0300
    P0366
    P0520

    2015-08-16 15.10.59.jpg

  7. #7
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    Researching codes that were thrown...It appears that there may be a limp mode associated with po068 when flowing too much air or MAP (like when you hack a new turbo to a n/a motor??). Playing with this now.

  8. #8
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    Are you overboosting?

  9. #9
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    12 to 14 psi...seems to hold pretty well.

  10. #10
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    did you increase the airflow trigger on the p0068 code?
    The most hated, make the most power.
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  11. #11
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    Yes, I significantly increased all 4 tables associated with the code. I have not fully tested as I have a new clutch now and trying to "break it in". Also, I suspect some grounding issue or shorting issue within the harness as I have many "low voltage" type error codes. I think I'm headed in the right direction for now.

  12. #12
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    The car is running "well". I still get intermittent codes po102 and po121 while driving. I have read elsewhere that they can be connected and if vacuum leak is not evident and shorting or lack of ground is not an issue to ignore them if turbo is added to n/a motor.

    Any opinions on this?

  13. #13
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    Quote Originally Posted by bajalobster View Post
    The car is running "well". I still get intermittent codes po102 and po121 while driving. I have read elsewhere that they can be connected and if vacuum leak is not evident and shorting or lack of ground is not an issue to ignore them if turbo is added to n/a motor.

    Any opinions on this?
    Interesting.

    I just installed a K04 turbo off an LNF on my LE5 and am having similar issues. I get P0121, P0300 and (can't remember the code) fuel bank 1 lean. The car is on a basic tune and my tuner should be out here tomorrow but there is another issue that I think may be tied to this.

    When I'm driving, and it can be at WOT, cruise or at idle, the engine stumbles, power is quickly reset to all gauges and ODBII port, the SES light comes on briefly and then goes out (like when you first start up the car) and then everything is fine.

    It's hard to get a scan on the car because when it stumbles, the tuner stops logging. Like I said, it is as though the car "shuts off" for a millisecond though it doesn't. If it did the alarm would trigger like when you turn the key on and off real quick while driving.

    I figure the P0300 and fuel bank 1 lean codes are from not finalizing the tune but wonder if the stumble and P0121 are tied to another issue. Guess I'll check for vac leaks tomorrow (though there are no sensors before the MAF which is in the cold pipe just before the TB) and make sure the plug on the TB is good.

    Just interested if you found anything else bajalobster.

  14. #14
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    Just to follow up on this in case anyone is interested, my issue with the hiccup eventually turned out to be a failing ECU. I got a P0606 error code and the symptoms began to get worse. Poor running on throttle and more frequent hiccups. Swapped out ECMs, reset, case learn and no more hiccups. Now I just RPM dropping when I am coming to a stop. Car recovers but I've been told I may need to play with the coast down timing. See if that fixes it.

  15. #15
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    Quote Originally Posted by Robotech View Post
    Just to follow up on this in case anyone is interested, my issue with the hiccup eventually turned out to be a failing ECU. I got a P0606 error code and the symptoms began to get worse. Poor running on throttle and more frequent hiccups. Swapped out ECMs, reset, case learn and no more hiccups. Now I just RPM dropping when I am coming to a stop. Car recovers but I've been told I may need to play with the coast down timing. See if that fixes it.
    Thanks a lot for the follow up on the issue.

  16. #16
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    No problem. I know I always hate it when someone posts an issue like this and doesn't update the resolution they found for it. LOL I wasn't going to be THAT guy.

  17. #17
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    I know this is a HUGE necro thread. but I also found the issue to the car dipping and stumbling when coming to a stop. LE5 require more idle torque when in coastdown, so I've found that bumping up the Throttle Follower Torque table around the 850, 950, and 1200 rpm cells to about what your idle torque logs at fixes the issue of the car trying to die.

    I know reviving old threads is bad, but I think that this (and many other threads) get a LOT of pageviews from searches, so if I were looking for the answer, I would love it if someone followed up with a solution.

    Throttle Follower Torque.png
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