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  1. #1
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    Knock sensor threshold correlation to post-shift timing discussion.

    As many of you know, I have been plagued with 6AT timing flatline issues immediately post-shift and I've been logging all sorts of variables in the car to figure out why it's happening.

    History:
    Updated to newest DME software as of 2/2011 after HPFP recall.

    Started flatlining timing on cylinder 1, based on the logging ability of both the JB4 and Procede.

    Toyed with fuel trims, did nothing.

    Switched to Cobb Stage 2 RACE, flatlined as well. Rob @ Cobb removed Fuel Mode 6 which he believed to cause the timing flatline, although improved, did not resolve issue.

    Logged "torque limit active", nothing of note.

    Logged "Timing Correction and Knock Voltage" on Cylinders 1 and 5, the two cylinders that typically flatline post-shift. After logging these parameters for the first time, I see that the ECU is pulling timing immediately post-shift by upwards of 9 degrees on both cylinders.

    Now the question is, could it be at all plausible that the ECU is perceiving external noise (DCIs, transmission noise as possible) to be knock immediately after the gear shift? Could it be actual knock? What is strange is, it isn't isolated to the higher gears, it does happen occasionally with the lower gear shifts such as a 2-3. I never had the pleasure of doing a 1-2 WOT shift so I can't comment there.

    Please discuss. Click here to enlarge

  2. #2
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    Datalogs of the two examples logged today. Perhaps I need more meth than a CM7? Who knows. That's not the important part.

    Click here to enlargeClick here to enlarge

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    It's possible the knock sensors are just hypersensitive during the shift. Similar to how they normally are around the 4200rpm. Just desensitize the knock sensors in that range and see if the motor holds together. Click here to enlarge

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    It's possible the knock sensors are just hypersensitive during the shift. Similar to how they normally are around the 4200rpm. Just desensitize the knock sensors in that range and see if the motor holds together. Click here to enlarge
    Ah, Mr. Burger is awake Click here to enlarge Here are three more datalogs with Knock Volt / Timing Correction data zoomed in. Like fuel trims, there's SOME correlation but nothing strong. Dropping down to a single CM7 feels like the car is faster based on the old butt dyno, but a lot of timing corrections going on, but on three 2-3-4 pulls, timing flatlined in cylinder 1 2 out of 3 times. I guess that's an improvement? LOL

    Just by looking at the knock voltage, can you guess which log flatlined?
    Click here to enlargeClick here to enlargeClick here to enlarge

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    and see if the motor holds together. Click here to enlarge

    haha....love that part




    why would only your knock sensors be having this issue though.....have you tried swapping them out? maybe switch sensors with a local N54.
    Never thought I would see the day...
    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Life is so much more fun with a nemesis. I miss Shiv. Click here to enlarge
    Click here to enlarge

  6. #6
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    Click here to enlarge Originally Posted by Forced Air Click here to enlarge
    haha....love that part




    why would only your knock sensors be having this issue though.....have you tried swapping them out? maybe switch sensors with a local N54.
    Nothing's wrong with the knock sensors, it's DME software related. Considering there is likely a table in there that tells the ECU how to handle the Knock Volt feedback, the issue can also likely be tuned out by rewriting the tables based on the older DME software IF a correlation exists. I'm talking out of my ass right now, but wouldn't it be nice if I was right?

    Terry knows this is a fairly common problem for automatics on the later DME software. Click here to enlarge

    -edit- curious. I manually shifted into 4th on the one log that flatlined, and redlined 3rd gear in the others and didn't flatline. Coincidence? Could it actually mean something? I suppose I will need to do four more logs, 2 with a manual shift at 6400, 2 with a redline shift.

    -double edit- I should try shifting manually at 6000 RPM like Shiv's "Aggressive Map" testimonials do. Click here to enlarge I wonder if that's how they "fixed" it.
    Last edited by themyst; 11-19-2011 at 03:00 AM.

  7. #7
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    Where is the knocksensors located? I thought bmw used the coils/plugs as probes but I havent been able to confirm that.
    Click here to enlarge
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    SO Ben you have it set on manual mod (M1) and let the car shift on its on to 3rd and then on fourth you upshifted with the paddles into fourth at what rpm?

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    Manual mode wont upshift for you.

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    Yes it will
    2015 F82 M4 - DCT - YMB
    2008 E90 335xi - AT - TSM

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    Click here to enlarge Originally Posted by Matt@Camber-Toe Click here to enlarge
    Manual mode wont upshift for you.
    Maybe the DCT boxes has diffrent firmware but a friends z4 35is DCT box does automatic upshifts even in manual mode Click here to enlarge
    Click here to enlarge
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  12. #12
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    6AT Manual mode will upshift for you if you're just before redline. It won't bump off the rev limiter like on a manual.

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    Two more logs, actually I did three, but that one traction intervened and the trans shifted, so I threw it out.

    One log I let the trans shift itself, one log I paddle shifted early at 6400. The one I paddle shifted flatlined. The knock sensor activity is clearly different between the two. I think we now know what is causing this. The challenge is knowing if it can be fixed....

    Click here to enlargeClick here to enlarge

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    Appears that if a cylinder is too quiet the ecu pulls timing as well. Interesting!

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    Anybody knows what the different fuel modes mean? I get 20, 2 and 6 in some logs i took. Also themyst do you have an excel done for the graphing? having an hard time with it... Cobb should really add to their accessport software a graphing prog.
    07 335i AT - MOTIV 750 - MHD BMS E85 - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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  16. #16
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    Fuel mode 2 is normal operation I see 20 when I'm under light throttle don't know what it means and I've explained what fuel mode 6 is numerous times. Means car thinks egts are too high and throws fuel at the cats.

    I use open office for graphing, easier to use than excel.

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    I think Fuel mode 20 might be the striated fuel mode under low load Rob talked about a bit back in an argument with Shiv @ E90. Some sort of economy mode that uses fuel to control engine speed with the throttle plate opened fully.

  18. #18
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    Click here to enlarge Originally Posted by Bleep Click here to enlarge
    I think Fuel mode 20 might be the striated fuel mode under low load Rob talked about a bit back in an argument with Shiv @ E90. Some sort of economy mode that uses fuel to control engine speed with the throttle plate opened fully.
    funny thing is Shiv mentioned that to me in the context of fuel pressure...its in that infamous skype convo I think but basically he showed that he totally misunderstood what stratified charge/mode was all about, at least in the context of the N54...his words were along the lines of "no wonder cobb cars feel so anemic, they're running stock fuel pressure" and then told me to look up stratified mode and why raising fuel pressure to get the fuel to spray with higher fuel pressure into the cylinder is a good approach indicating that is what stratified charge/mode was about Click here to enlarge just a tad misinformed, how's that possible from a PRO tuner lol
    Click here to enlarge

  19. #19
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    cobb cars feel anemic? Really? lol.

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    1 out of 1 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by themyst Click here to enlarge
    cobb cars feel anemic? Really? lol.
    I have better throttle response and more power on pump gas than I did with my Procede and it definitely drives better...

    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    funny thing is Shiv mentioned that to me in the context of fuel pressure...its in that infamous skype convo I think but basically he showed that he totally misunderstood what stratified charge/mode was all about, at least in the context of the N54...his words were along the lines of "no wonder cobb cars feel so anemic, they're running stock fuel pressure" and then told me to look up stratified mode and why raising fuel pressure to get the fuel to spray with higher fuel pressure into the cylinder is a good approach indicating that is what stratified charge/mode was about Click here to enlarge just a tad misinformed, how's that possible from a PRO tuner lol
    Yeah I read that and decided it wasn't even worth mentioning. There's a wealth of laughable material in that conversation even to an idiot like me. Particularly how he wanted to be so secretive about the WOTBOX because he was gonna release a new Procede with it haha.
    Click here to enlarge

  21. #21
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    glad after all that some people actually read it Click here to enlarge
    Click here to enlarge

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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    glad after all that some people actually read it Click here to enlarge
    the GF looked at me funny after I'd been reading a wordpad doc for like 20 min. I was gonna take out my favorite parts and put them in a txt file but decided to get dinner instead
    Click here to enlarge

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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    funny thing is Shiv mentioned that to me in the context of fuel pressure...its in that infamous skype convo I think but basically he showed that he totally misunderstood what stratified charge/mode was all about, at least in the context of the N54...his words were along the lines of "no wonder cobb cars feel so anemic, they're running stock fuel pressure" and then told me to look up stratified mode and why raising fuel pressure to get the fuel to spray with higher fuel pressure into the cylinder is a good approach indicating that is what stratified charge/mode was about Click here to enlarge just a tad misinformed, how's that possible from a PRO tuner lol
    make sure stratified is spelled correctly otherwise he will be all over your arse lol

  24. #24
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    OK, I've done 5 more 3-4 pulls today, a few at redline, a few at 6400, even tried one at 6000, none of them flatline. I'm seeing timing drops in cylinder 5 on each run though. I'm on a 90/10 mix and might have to bump it up to 100% to get more octane to that cylinder, but overall the log is super clean. I'm almost afraid to change what ain't broke.

    I'm actually getting BETTER IAT suppression with a higher meth mix than with the 75/25 - 80/20 mix I was using before. Ambient temperature was 52 degrees, one log shows 45.5 degree IAT, almost 7 degrees below ambient!

    Just to give folks an idea as to what was done:

    Dumped meth tank, running 90/10 mix
    reset 6AT adaptations by holding down gas pedal for 30 seconds with ignition on
    unmarried Cobb AP, drove around stock for 3-5 miles, reloaded directly to Stage 2 RACE map.

    Maybe a 6AT trans adaptation did the trick getting it to cooperate with the Cobb? Honestly, I don't know.

    Being that this issue is known to recur at random, I'm not going to claim victory yet, but I see light at the end of the tunnel....

    Maybe another trip to Atco is in order? Click here to enlarge

  25. #25
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    hmmm...sounds promising but if you want the honest opinion, i think it'll be back...just don't see how what you've done could "fix" it, but in any case, good luck though...if it were me and the track was open I'd definitely take it there but this time get some weight reduction and DRs on the back and go for a record Click here to enlarge
    Click here to enlarge

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