Hyperblade Posted February 19, 2022 Report Share Posted February 19, 2022 Setup: K20 with a Honda S2000 AP1 Gearbox and G4X XtremeX. The speed sensor signal keeps dropping out just over 5000 Hz (DI2), consistently, around 130km/hr with current setup. What is the best way to diagnosis where the fault lies? Form a configuration standpoint I've checked out the Link S2000 Base map and it has the following Driving Wheel Speed Correction: 0.0% Slip Filter: 20Hz Pull Up Resistor: Off Active Edge: Falling Freq Filter: None Calibration 9600 Where as mine(which has been on dyno at tuner) has Driving Wheel Speed Correction: -10.0% Slip Filter: None Pull Up Resistor: On Active Edge: Rising Freq Filter: None Calibration 12974 Which obviously stands out as being different in the Active Edge, (but could be because the Honda S2000 base map is for plugin ECU), but would that cause it to just drop the signal over 5000Hz? I wouldn't have thought so which leads me to think the sensor may be faulty? What else can I check? Video Here: Quote Link to comment Share on other sites More sharing options...
Adamw Posted February 19, 2022 Report Share Posted February 19, 2022 Does turning on the pull-up resistor help? Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted February 19, 2022 Author Report Share Posted February 19, 2022 1 hour ago, Adamw said: Dose turning on the pull-up resistor help? It was on when i had the issues, doesn't get a signal when it's off. Quote Link to comment Share on other sites More sharing options...
Adamw Posted February 20, 2022 Report Share Posted February 20, 2022 Well the picture of your setup that you attached shows it turned off hence my suggestion. You will have to get an oscilloscope on it to see what is happening to the signal at high speed. Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted February 21, 2022 Author Report Share Posted February 21, 2022 5 hours ago, Adamw said: Well the picture of your setup that you attached shows it turned off hence my suggestion. You will have to get an oscilloscope on it to see what is happening to the signal at high speed. Sorry about that, took that then decided to actually write it down so it was searchable in the future for others, have removed that image now. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted April 9, 2022 Author Report Share Posted April 9, 2022 @Adamw I swapped in a new sensor as I couldn't get access to an oscilloscope, same issue. I confirmed the pull up resistor has to be on for me to get any signal, so not sure how the S2000 base map works with it off? But I did notice something different this time, the Duty Cycle hits 100% on DI2 when it cuts out. How is that duty cycle calculated? Is it based on a previous max value the input has reached, or is it based on what the ecu supports in the firmware? Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 9, 2022 Report Share Posted April 9, 2022 Duty cycle is just the percentage of high vs low. Does the duty cycle change as speed increases or just suddenly when the signal drops out? Can you attach your tune and a log. Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted April 9, 2022 Author Report Share Posted April 9, 2022 30 minutes ago, Adamw said: Duty cycle is just the percentage of high vs low. Does the duty cycle change as speed increases or just suddenly when the signal drops out? Can you attach your tune and a log. When looking at it in real time I thought the duty cycle changed with speed in a consistent fashion, but looking at logs that doesn't appear to be the case. Files here: https://drive.google.com/drive/folders/1FnPhQe_9f1wKRYdibQIAtl0XKAYnfxF8?usp=sharing Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 9, 2022 Report Share Posted April 9, 2022 Ok, I tested you file on the bench with a simulated engine running etc so full processor load, I can get up to about 13000Hz before it tops out. So my best guess is at higher frequencies the signal voltage is no longer meeting the thresholds. It may need a stronger or weaker pull-up, but it is hard to guess without a scope showing what is wrong with the signal. Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted April 10, 2022 Author Report Share Posted April 10, 2022 4 hours ago, Adamw said: Ok, I tested you file on the bench with a simulated engine running etc so full processor load, I can get up to about 13000Hz before it tops out. So my best guess is at higher frequencies the signal voltage is no longer meeting the thresholds. It may need a stronger or weaker pull-up, but it is hard to guess without a scope showing what is wrong with the signal. Ok thanks for looking into it, will try and get a scope somehow. Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted January 20 Author Report Share Posted January 20 On 4/10/2022 at 9:43 AM, Adamw said: Ok, I tested you file on the bench with a simulated engine running etc so full processor load, I can get up to about 13000Hz before it tops out. So my best guess is at higher frequencies the signal voltage is no longer meeting the thresholds. It may need a stronger or weaker pull-up, but it is hard to guess without a scope showing what is wrong with the signal. So it's taken me a bit but I finally got the Oscilloscope trace for you... I had someone fairly knowledgeable do it, and everything on the sensor looks good and as expected and the signal is stable and strong. I'm curious as to how the S2000 plugin ecu works fine, unless you've got some additional hardware? Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 20 Report Share Posted January 20 It looks like you possibly have more than 1V ground offset there, especially at higher RPM when that fuzz appears on the signal. Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted February 6 Author Report Share Posted February 6 On 1/20/2024 at 10:50 PM, Adamw said: It looks like you possibly have more than 1V ground offset there, especially at higher RPM when that fuzz appears on the signal. Good spotting, yes we do. We are looking at options for trying to work out where that may be coming from as there doesn't seem to be any settings in ECU to adjust the threshold (just bury head in sand and ignore the problem approach to solving it). Plug A and Plug B both have sensor grounds (Gnd Out) pins at the moment all sensors are connected to A and B has nothing on it. I'm assuming internally are they treated the same? e.g. you don't need to hook sensors that are connected to plug B to have sensor gnd from plug b? Quote Link to comment Share on other sites More sharing options...
Adamw Posted February 6 Report Share Posted February 6 The DI thresholds are determined by hardware, adjustable thresholds on high frequency digital inputs add significant complexity and cost. Are you sure the VSS is grounded to sensor ground? Assuming it is then I would say the only way to get that sensor to switch to ground as it should would be to put less power through it. I would try turning the internal pull-up off and add a 5kohm pull-up to 5V (DI's are normally pulled up to 12V). Quote Link to comment Share on other sites More sharing options...
Hyperblade Posted February 6 Author Report Share Posted February 6 16 hours ago, Adamw said: The DI thresholds are determined by hardware, adjustable thresholds on high frequency digital inputs add significant complexity and cost. Are you sure the VSS is grounded to sensor ground? Assuming it is then I would say the only way to get that sensor to switch to ground as it should would be to put less power through it. I would try turning the internal pull-up off and add a 5kohm pull-up to 5V (DI's are normally pulled up to 12V). Yes, grounded to sensor ground. Ok can give that a go. The other thing we were thinking of trying is running a single sensor ground wire back from the bulk head connector to Plug B (so not being spliced into the other sensor grounds that go into plug A) Currently the VSS is running off 5V, is it worth trying it at 12v and turning pull up off? Quote Link to comment Share on other sites More sharing options...
Adamw Posted February 6 Report Share Posted February 6 I think it will need either a lighter 5V pull-up, or another thing you could try is connecting a small signal diode in line with the signal, something like a 1N4148 will do (stripe pointing to ecu), this should drop the voltage seen at the ecu by about 0.6V. Quote Link to comment Share on other sites More sharing options...
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