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Thread: Wideband sensor response time

  1. #1
    Advanced Tuner NJ_Phil's Avatar
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    Wideband sensor response time

    I see a lot of posts about using CAN, analog or serial for connecting the controller to the VCM. Some say faster is better, CAN is best because it's faster than serial. Analog is better because serial is too slow, etc..
    The datasheet for the Bosch LS 4U says response time is "under 100ms" so it's pretty damn slow and running serial should have no impact. Other sensors may be higher precision or slightly faster but surely not under 10 ms simply because of how O2 is measured within the sensor, so what difference does it mean if the VCM gets 100x more readings of the same value?

    For instance, serial output:
    Assume ASCII "12.7"+<cr> coming out of the controller back to back @ 9600 would be 4 bytes x 10 x 1/9600 = about 5ms per transmission or 20 x faster than the response of the sensor itself?
    Plus the additional benefit of elimination of noise from not running an analog signal between the controller and VCM, + no scaling, offsets, etc..

    Am I missing something with all the emphasis on HS WB acquisition on the VCM?

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    If you ask me, the method of capture doesnt have much effect on the reading delay. The delay is just inherent in the sensor design

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    Lol. There's been about a hundred posts on this subject lately. You guys have some reading to do! Here's one of the threads...

    http://www.hptuners.com/forum/showth...d-beta-testers


    Here's the condensed version...

    Widebands through the CAN network are the future. Nobody will be using analog 0-5v conversion for wideband logging. Get one of the new AEM widebands, put it in and log away! By far the most accurate and fastest consumer wideband solution we have right now. I've got probably close to 10k miles on a pair of them and they have been DEAD ON accurate and fast.

    And yes, the speed that you can read the wideband data makes a HUMONGOUS difference in tuning. Have a setup that is super accurate but slow and you'll spend hours and hours chasing your tail trying to tune mixtures. The CAN based AEM widebands make "copy-paste" tuning brainless. Get one and start tuning with it. I've yet to hear of someone that wasn't happy with theirs.
    Check out my V8 Sky build video. It's pretty cool!...

    https://youtu.be/2q9BuzNRc3Q

    https://www.youtube.com/user/gmtech16450yz

  4. #4
    Advanced Tuner NJ_Phil's Avatar
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    Read that entire thread. That's why I asked the question

    My point is if you have a sensor with a response time of 100 milliseconds, why bother sampling it 100 times a second?
    You're just going to read the same value
    Last edited by NJ_Phil; 08-09-2016 at 04:34 PM. Reason: clarity

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    The Bosch LSU4.9 sensor's response time is much faster than 100ms. They list it as "<100ms" which is, technically true. It is less than 100ms. But, depending on the controller, the response time can be as quick as 10ms, or, maybe, better. The internal limit of the sensor, itself, is probably around 4ms.

    As noted, with the newer AEM controllers, the response is very fast. Even single cylinder events are visible up into low to mid-range RPM.

  6. #6
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    I was about to say.. 100ms sounds a little slow
    Post a log and tune if you want help

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  7. #7
    Advanced Tuner NJ_Phil's Avatar
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    Pretty sure this is old news but the chart below clearly shows the 4.9LSU has response times to gain the benefit from higher sample rates, so question answered and thanks.
    Also shows lack in sensitivity on the PLX and noise and low resolution of Innovate, so I'll buy the kit based on that and how clean it is. And yes, go with CAN and kick analog and serial to the curb.
    http://www.hptuners.com/forum/attach...7&d=1470834667

    Not convinced the lean on tip out is real and maybe pressure related, or even sensor or placement differences on that UMS test, but guess that's a different topic.
    Steady state AFRs are also off 1.5 at the end of the trace so apples ain't apples on this setup.
    http://www.hptuners.com/forum/attach...8&d=1470834780
    Attached Images Attached Images

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    I've been meaning to run my PLX and AEM 30-0333 side by side but haven't gotten to it yet.. BUT, I've definitely seen things with the AEM that never showed up on the PLX. Some lean spots at lower boost and it going rich at higher boost areas that are usually blasted through pretty quick. Never showed up on the PLX but I always had a bit of a lag in acceleration that started around 4,200 RPM's. Leaning that area out now that I have better data from the AEM WB has fixed it.
    Post a log and tune if you want help

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  9. #9
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    Quote Originally Posted by schpenxel View Post
    I've been meaning to run my PLX and AEM 30-0333 side by side but haven't gotten to it yet.. BUT, I've definitely seen things with the AEM that never showed up on the PLX. Some lean spots at lower boost and it going rich at higher boost areas that are usually blasted through pretty quick. Never showed up on the PLX but I always had a bit of a lag in acceleration that started around 4,200 RPM's. Leaning that area out now that I have better data from the AEM WB has fixed it.
    Nice... Always good when real results back up the data, that's all that matter in the long run.
    Just ordered the 30-0333 and looking forward to working with it. Glad I read about it before pulling the trigger on that Cobalt series gauge.
    Maybe I'll duplicate the output of the LS4U with a signal generator too see what the exact response time is, but then again bigger fish await

    ANY COUPON CODES FOR FORUM MEMBERS ?? Maybe free shipping.. Please
    Last edited by NJ_Phil; 08-10-2016 at 09:57 AM. Reason: plea for coupons

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    Summit had them for $222 last time I checked, but they aren't in stock

    Jegs has them in stock and will price match

    So.. I'd call Jegs and see if they'll match Summit's price. Buddy did this a few days ago and they matched Summit's price. Ordered Monday, had it on Wednesday

    Or you can sometimes get them on Amazon for $209, but last time I did this I had to wait about 2 weeks to get it
    Post a log and tune if you want help

    VCM Suite V3+ GETTING STARTED THREADS / HOW TO's

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  11. #11
    Advanced Tuner NJ_Phil's Avatar
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    Quote Originally Posted by schpenxel View Post
    Summit had them for $222 last time I checked, but they aren't in stock

    Jegs has them in stock and will price match

    So.. I'd call Jegs and see if they'll match Summit's price. Buddy did this a few days ago and they matched Summit's price. Ordered Monday, had it on Wednesday

    Or you can sometimes get them on Amazon for $209, but last time I did this I had to wait about 2 weeks to get it
    Seeing $259 from jegs and $197 from Summit but that's for the 30-0300. AEM has the 30-0333 for $235, OBDII tap included and ready to go but gets $18 shipping.
    AEM factory direct seems like the best deal and I'm just going to go for that.

    Beat this Wideband selection horse to death and glad it's over. Hope selecting the right PDS goes easier.

  12. #12
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    Either way will work. Getting jegs to price match is still cheaper than aem direct. And free shipping. Exact same thing as aem direct.

    And no use looking at the -0300, it won't work with HPT without a reflash by dr.mike

    Either way, not a big deal in the grand scheme of things
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    Quote Originally Posted by NJ_Phil View Post
    Steady state AFRs are also off 1.5 at the end of the trace so apples ain't apples on this setup.
    http://www.hptuners.com/forum/attach...8&d=1470834780
    A few notes about that trace.

    1. at the end of the trace, each WB is showing its maximum value ( i.e. @ 5v ) because the actual value is out of range. Probably near free air. So AEM shows 1.22 Innovate shows 1.50, etc. None of them are "right".

    2. The innovate outputs in steps of 82ms. So, it loses all of the detail faster than that. And the signal is delayed by about the same 82ms.
    Both the AEM and PLX caught what looks like a misfire event, while going lean. It also has a lot of noise; probably from the sensor's heater driver.

    3. The PLX did not really respond to the rich dip that both the AEM and Innovate showed. It kinda flat-lines at 11.3 while the other two WBs show rich spots below 10.0 It seems that the PLX responds faster when going lean than when going rich.

    4. As expected, when the AFR is steady, all 3 WBs basically agree on the value.

  14. #14
    Advanced Tuner NJ_Phil's Avatar
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    Quote Originally Posted by dr.mike View Post
    A few notes about that trace.

    1. at the end of the trace, each WB is showing its maximum value ( i.e. @ 5v ) because the actual value is out of range. Probably near free air. So AEM shows 1.22 Innovate shows 1.50, etc. None of them are "right".

    2. The innovate outputs in steps of 82ms. So, it loses all of the detail faster than that. And the signal is delayed by about the same 82ms.
    Both the AEM and PLX caught what looks like a misfire event, while going lean. It also has a lot of noise; probably from the sensor's heater driver.

    3. The PLX did not really respond to the rich dip that both the AEM and Innovate showed. It kinda flat-lines at 11.3 while the other two WBs show rich spots below 10.0 It seems that the PLX responds faster when going lean than when going rich.

    4. As expected, when the AFR is steady, all 3 WBs basically agree on the value.
    Fully understood Mike, and thanks,

    Not to continue on this Wideband Merry go round but I happened to see pressure affects the sensor and changes between 1 and 2 bar can affect output around 15%. Not that I understand the dynamics of airflow on automotive systems but it looks like it can get pretty crazy before and after the collector and variations of 2 bar are possible during a tip in or tip out of the throttle at higher RPMs. If this is the case then sensor placement isn't trivial and the X-Pipe might be the best place for it. Also the use of cats, after the sensor of course, would act like a pressure amplifier even with the slightest restriction of airflow and make things worse. Just more a curiosity question but does pressure changes factor into the accuracy or does the controller try to compensate for this in some way?

    Phil