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Thread: What's with my boost?

  1. #1

    Default What's with my boost?

    I took a data log and was surprised to see my boost so low. Think it was with the Cobb ots stage 1. its the same when I flashed back to stock and did a log.

    Confusingly, my boost gauge shows around 15psi+ but the data log says very differently. I have the boost guage teed into the BPV line.

    Boost leak? and wtf is with the discrepancy between the OBD output and the boost gauge?

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    Attached Files Attached Files

  2. #2

    Default What's with my boost?

    to me, everything seems within spec for the higher boost you are reading with the boost gauge. Doesn't look like there is a boost leak - your MAF shows consistent readings for higher boost levels - load follows typical course for higher readings - if you were actually having boost as the AP is reading the car would feel noticably slower and would feel strange when it was pulling like hesitating.

    perhaps the MAP sensor is dirty or faulty?

    try and pull the map sensor out from the intake manifold, visually inspect it, clean it and put it back in, might help.
    Last edited by Rayd; 22-09-2013 at 11:22 AM.

  3. #3

    Default

    Quote Originally Posted by rayd View Post
    perhaps the MAP sensor is dirty or faulty?

    try and pull the map sensor out from the intake manifold, visually inspect it, clean it and put it back in, might help.
    thanks Ray, I'll give it a go. But if the boost reading is not correct, then how is my car not overboosting? the WGDC doesn't reach 100%

  4. #4

    Default

    Quote Originally Posted by lup15 View Post
    thanks Ray, I'll give it a go. But if the boost reading is not correct, then how is my car not overboosting? the WGDC doesn't reach 100%
    Because there's only a certain high limit for the WGDC to reach and that limit is sorted through the tune itself. So without being able to see the actual boost its hard to see how it's behaving.

  5. #5

    Default

    I cleaned both the MAF and MAP sensors flashed to Cobb Stage 1 (TIH, SF, IC, 98) but I don't think it's made a difference. new 3rd WOT attached

    I've noticed that I don't get full boost when going WOT and the boost seems to jump around a bit. But when I go part throttle (these were in 5th) its smooth and maintains a higher boost level. I think I can rule out a boost leak based on this.

    But what is happening on WOT and why can't I maintain the higher boost level? I thought the Cobb OTS maps were boost target based?
    Attached Files Attached Files

  6. #6

    Default

    Something that strikes me as strange is that your throttle plate is opening to 86%
    I've never seen higher than 76-78% you might need to much around with your throttle tables or APP translation tables perhaps?

  7. #7
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    Default

    Quote Originally Posted by rayd View Post
    Something that strikes me as strange is that your throttle plate is opening to 86%
    I've never seen higher than 76-78% you might need to much around with your throttle tables or APP translation tables perhaps?
    must be a gen 1 thing... mine used to do the same
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  8. #8

    Default

    Yea I'm pretty sure a lot of logs I've seen for have 86% for WOT.

    @richierichness any words wisdom?

  9. #9

    Default What's with my boost?

    Quote Originally Posted by lup15 View Post
    Yea I'm pretty sure a lot of logs I've seen for have 86% for WOT.

    @richierichness any words wisdom?
    The 86vs76 probly is nothing , the throttle plate is 100% open at 74%+ anyway just found it strange to read that high.

    Anyway; i actually haven't seen this boost inconsistency issue before, so I can only take a guess as to the problem - hopefully rich can chime in with some insight.
    Last edited by Rayd; 24-09-2013 at 04:34 PM.

  10. Default

    I have to say this issue is very odd. Please post your map. And this time post a couple logs making sure IDC (injector duty cycle) and coolant temp are included.

    Questions:

    1. did you by chance add a 3 bar map sensor? (i have to ask)
    2. Have you tried any other OTS maps to see if it resolves this issue?
    3. What is your approx. altitude
    4. Have you updated your ATR and AP manager software?
    5. What year MS3?
    6. What's your vin #?
    Last edited by richierichness; 26-09-2013 at 05:25 AM.

  11. #11

    Default

    Thanks richie. I'll do the logs with the OTS tunes with the extra info. I'll also change back over to the stock airbox, put stock tune on then run some additional logs.

    Once I got all this, I'll respond again. Appreciate your insight

  12. Default

    I was doing some research on this issue and was only able to find one other instance. https://www.mazdaspeedforums.org/for...-boost-106718/

    Unfortunately the thread is a dead end and the OP never updated with a solution. I will come up with a theory after reviewing your new logs but here is what i'm thinking as of now. Either the map sensor is bad or your OTS map has a problem.

  13. #13

    Default

    Quote Originally Posted by richierichness View Post
    I was doing some research on this issue and was only able to find one other instance. https://www.mazdaspeedforums.org/for...-boost-106718/

    Unfortunately the thread is a dead end and the OP never updated with a solution. I will come up with a theory after reviewing your new logs but here is what i'm thinking as of now. Either the map sensor is bad or your OTS map has a problem.
    Yep, i suspected the same things... its strange that the car reads the boost fine under PT but not under WOT thought.
    @lup15 keen to hear more about this issue
    also, if your near me (sydney suburbs) feel free to come round and swap your MAP sensor for my spare stock 2.5 bar MAP sensor. that will at least get your one step closer to an answer

  14. Default

    I messaged the user on Mazdaspeedforums that was having this problem and this was his response.

    "I could never figure it out. I tried changing the MAP sensor, cleaning MAF, changing tune, changing the EBCS, nothing worked. Ended up trading the car in because of that and an issue I had with the axles. Having a similar problem?" ~abiezerf

    Like @rayd suggested, you should swap the MAP sensor with someone else to see if that resolves the problem. Another thing you can try is borrowing someones v2 AccessPort to see if that makes a difference. The good news is your car looks healthy. Assuming you can't figure out the problem, the car can probably be reliably tuned using a load tuning strategy (which is what I prefer).

    regards,
    Rich
    Last edited by richierichness; 26-09-2013 at 11:53 PM.
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  15. Default

    Hey I'm the guy Rich was mentioning before. I even got to the point of changing out my turbo, but nothing I did could cause my boost to read right. I can look through my emails and pull up my datalogs if its any use to you. My car was a 2008.5 MS3. I also got some gray smoke after every WOT run, but not just a puff, more like a run of smoke for like 10-15 seconds.

  16. #16

    Default

    ok, so bringing this thread back to life after I've finally did some further troubleshooting

    This is what I have tried so far, but still got the same issue:
    1) changed the MAP sensor (thanks @Grumpy)
    2) boost leak test, no leaks (thanks @Grumpy again)
    3) tried Cobb Stage 1 and 2 OTS tune
    4) read the boost via a different OBD reader (PLX Kiwi) and the same results

    I have noticed that my LTFT is hovering around -18% with the cooler weather. Was around -10% during the warmer months. So its running rich to super rich... OTS tune or some other culprit, not too sure

    I also have a notion that the ECU might possibly be corrupted as I had a Hypertech tune previously. I think I forgot to put the stock tune back on before I flashed it with Cobb. Dunno.

    Also, its weird that I have the same issue as @abiezerf who also had the 2008.5 model. Is there something that changed in the ECU? Who knows...

    Stumped is all I can say. If @Rayd or anyone else has any ideas, feel free to suggest
    Last edited by lup15; 10-06-2014 at 02:37 PM.

  17. #17

    Default

    You might have to resort to a pure load based tune i think, essentially makes the boost reading redundant with regards to the tune.

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