mike2016 Posted December 8, 2020 Report Share Posted December 8, 2020 Hi Guys, I'm running Link G4+ in my BNR32 Just installed a powertune digital dash, but the boost reading is 1 bar(14.7psi) off actual boost reading (it's reading from MAP) how do you can the CAN bus to display MGP value to the dash instead? or is there a way to offset the value so the dash can display the actual boost value? Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 8, 2020 Report Share Posted December 8, 2020 Both MAP and MGP is already sent in the generic dash stream. Power tune must be using the wrong one? Is the table you are looking at in the dash actually named "MGP" or something else? Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 9, 2020 Author Report Share Posted December 9, 2020 20 hours ago, Adamw said: Both MAP and MGP is already sent in the generic dash stream. Power tune must be using the wrong one? Is the table you are looking at in the dash actually named "MGP" or something else? Powertune is using MAP, and the display is 14.7 psi higher than the actual reading of course... the table i'm looking at is MGP in Analog Inputs table, but it's not shown in Powertune dash. i contact them already, they are working on a fix... apparently they seem to have confused MGP as MPG (fuel consumption)... on a side note, which parameter I should be using to display the actual AFR on the dash? i can't seem to find the one that displays actual AFR, but only Lambda value around 0.xx - 1.xx Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 9, 2020 Report Share Posted December 9, 2020 All data sent out over CAN is in the native "metric" units. This means exhaust mixture is in units of Lambda, temperatures are sent in deg C and pressures in Kpa. Most dash systems have some way to to change the display units on screen. If your dash doesnt then you could set up a custom stream with a multiplier of 14.7 (assuming your fuel is petrol) to receive a AFR value at the other end. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 9, 2020 Author Report Share Posted December 9, 2020 34 minutes ago, Adamw said: All data sent out over CAN is in the native "metric" units. This means exhaust mixture is in units of Lambda, temperatures are sent in deg C and pressures in Kpa. Most dash systems have some way to to change the display units on screen. If your dash doesnt then you could set up a custom stream with a multiplier of 14.7 (assuming your fuel is petrol) to receive a AFR value at the other end. that's good info. The PowerTune dash can change from Metric to Imperial units, for temp and pressure, but not Lambda. do i set up a secondary stream or add a frame in the primary stream ? also for Boost, since PowerTune is using MAP instead of MGP as Boost, it's 14.7 psi / 1 bar too high for actual boost, how can i make it display the actual value? Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 9, 2020 Report Share Posted December 9, 2020 Attach your ecu config, I will take a look Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 9, 2020 Author Report Share Posted December 9, 2020 11 minutes ago, Adamw said: Attach your ecu config, I will take a look Attached! btw, this is before i changed the settings in CAN Setup. all i did after i installed the PowerTune dash was changing the stream to Generic Dash Stream in Can Settings, in CAN 1 r32gtr.pclr Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 9, 2020 Report Share Posted December 9, 2020 For the MAP, what is the channel named in the dash - do they call it "Boost" or MAP? Is it currently displaying a number that matches the MAP reading in PC Link? Im not sure if I can just subtract 100KPa off the MAP value that is sent out as in the data stream they are decoding MAP is not specified to be signed - so it cant read negative values for vacuum. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 9, 2020 Author Report Share Posted December 9, 2020 9 minutes ago, Adamw said: For the MAP, what is the channel named in the dash - do they call it "Boost" or MAP? Is it currently displaying a number that matches the MAP reading in PC Link? Im not sure if I can just subtract 100KPa off the MAP value that is sent out as in the data stream they are decoding MAP is not specified to be signed - so it cant read negative values for vacuum. They named MAP as Boost in the dash, it matches 100% exactly as the reading in the PC Link. all i really need is to read positive boost pressure correctly, vacuum is not important Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 9, 2020 Report Share Posted December 9, 2020 MAP is sent out as a 16bit integer value which means its value can be between 0 & 65535. So if I subtract 100 from the MAP value, anytime the engine is in vacuum (i.e below 100kpa), the ecu cant send out a value less than zero so it will overflow and start counting backwards from 65535kpa. So if your engine idles at 50kpa MAP for instance your boost gauge will show 65485. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 9, 2020 Author Report Share Posted December 9, 2020 21 minutes ago, Adamw said: MAP is sent out as a 16bit integer value which means its value can be between 0 & 65535. So if I subtract 100 from the MAP value, anytime the engine is in vacuum (i.e below 100kpa), the ecu cant send out a value less than zero so it will overflow and start counting backwards from 65535kpa. So if your engine idles at 50kpa MAP for instance your boost gauge will show 65485. it seems mine is idling at 7psi MAP, so it's still positive. Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 9, 2020 Report Share Posted December 9, 2020 10 minutes ago, mike2016 said: it seems mine is idling at 7psi MAP, so it's still positive. Correct, because MAP never goes negative. 50kpa or 7psi is pretty typical idle MAP. But your 7psi at idle won’t still be positive when you subtract 14.5psi from it... Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 9, 2020 Author Report Share Posted December 9, 2020 21 minutes ago, Adamw said: Correct, because MAP never goes negative. 50kpa or 7psi is pretty typical idle MAP. But your 7psi at idle won’t still be positive when you subtract 14.5psi from it... What do you suggest the best approach to this ? Also i reached out to Powertune to ask them if they can label MGP as Boost. Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 9, 2020 Report Share Posted December 9, 2020 It needs to be fixed on their end. MAP is sent out 1:1 so cant go negative. MGP is sent out with a 100kpa offset to allow the receiving device to interpret negative values. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 10, 2020 Author Report Share Posted December 10, 2020 Problem solved. Powertune fixed it and sent an update to the dash. They didn't include MGP in the dash. I didn't get a chance to start the car yet, but with engine off it's 0 boost now so it should be good. i'll drive the car tomorrow to verify. Btw, is actual AFR ratio sent in the data stream? Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 10, 2020 Report Share Posted December 10, 2020 11 minutes ago, mike2016 said: Btw, is actual AFR ratio sent in the data stream? No, just Lambda. That one you can just multiply in a custom stream though to make the number read in AFR. - Although it is still going to be labelled Lambda on the screen by the looks. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 10, 2020 Author Report Share Posted December 10, 2020 1 hour ago, Adamw said: No, just Lambda. That one you can just multiply in a custom stream though to make the number read in AFR. - Although it is still going to be labelled Lambda on the screen by the looks. that's fine. should i set up Stream 2 for that or add a Frame in Stream 1? sorry i'm all new to this... Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 10, 2020 Report Share Posted December 10, 2020 Try this file, Lambda multiplied by 14.7 r32gtr new CAN.pclr Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 10, 2020 Author Report Share Posted December 10, 2020 13 hours ago, Adamw said: Try this file, Lambda multiplied by 14.7 r32gtr new CAN.pclr 166.8 kB · 0 downloads Thanks so much for your help. I'll give that a try today. also another question, in my ECU settings, pressure is set to display in PSI , does this affect the output of the CAN data? Powertune did another update on their dash, now it's displaying MGP but it's quite a bit lower than the actual boost. like when the car is boosting at 10psi, the dash is displaying 3-4psi Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 11, 2020 Report Share Posted December 11, 2020 4 hours ago, mike2016 said: also another question, in my ECU settings, pressure is set to display in PSI , does this affect the output of the CAN data? On 12/9/2020 at 8:23 PM, Adamw said: All data sent out over CAN is in the native "metric" units. This means exhaust mixture is in units of Lambda, temperatures are sent in deg C and pressures in Kpa. 4 hours ago, mike2016 said: Powertune did another update on their dash, now it's displaying MGP but it's quite a bit lower than the actual boost. like when the car is boosting at 10psi, the dash is displaying 3-4psi Can you compare MGP on the laptop and dash with engine running and let me know how they compare. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted December 11, 2020 Author Report Share Posted December 11, 2020 1 hour ago, Adamw said: Can you compare MGP on the laptop and dash with engine running and let me know how they compare. MGP on laptop matches boost gauge. the dash value seems to be 1/3 - 1/4 of the MGP value from laptop. I also reached out to Powertune again and asked if they did something wrong with their translation of the data. Quote Link to comment Share on other sites More sharing options...
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