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Topic: Multidisplay, a Open Source inCar Display, Logger (Read 103505 times) previous topic - next topic


but how are you reading the narrow band sensors ?
since they are very non-linear if you just remap the 0 to 1 volt on a linear scale and average out the measurements I don't think this give you any idea if it's really running lean, rich or stoich

are you looking for reversal between lean and rich reading at a maximum interval to declare the engine running stoich ? (and if no reversal happen after the set amount of time then it is rich or lean)

do you have real world sensor output on a graph ? that would be interesting !

for the calibration, yes I have access to the gases because I have a very well furnished hacker space =)

I read about the LC-1 and the "wbo2" controller and I do not believe they are accurate, sure they show numbers and come in a pretty case but I just don't think they are accurate enough for an engine management sensors, if you read the extremely interesting document about the "Precision Wideband Controller"
they say that you have to very accurately maintain and measure the temperature of the sensor using the heater, and also output with the sensor signal a "margin of error" signal for when the temperature goes to uncorrectable values (ice water splashing on the exhaust, or engine running more than 800 C )

also you have to apply current to the oxygen pump so the cell stays at 0.450V and it is the current value required to do that, that you read to get the air/fuel ration, and this current change for the same AFR if the cell is at a different temperature

I just don't think the LC-1 or the WBO2 controllers have all that working

you can get just the LC-1 controller with no display and no sensor that would be useful and almost cost effective but it's not good enough (or at least innovate motorsports isn't proving it's doing what it has to do to get accurate readings)
so we have to start over !

for starters, the LC-1 that my friend bought from IM themselves, doesn't come calibrated, they have a crude auto calibration, but I don't believe it works for better than 15% accuracy

good enough for the bling that an AFR gauge is but not for any kind of serious engine management

also I didn't say the Bosch 4.2 is a bad sensor but (and I can't find out where, right now) I read somewhere that the 4.9 was more tolerant of having high pressure exhaust gas blown on it, for example on the RB26 the oxygen sensor plug is right after the turbo outlet and right at the apex of a 90 degree turn in the pipe so the full blow of the exhaust is bearing down on the sensor , surely that would need a LSU4.9  to be accurate if what I read is true


Jul 24, 2010, 12:09 am Last Edit: Jul 24, 2010, 12:09 am by designer2k2 Reason: 1
the narrow band is attached to my bosch ecu, and i tapped into the signal line reading the voltage from it.
you can tell rich/lean but nothing else...

here you can see the output logged:

its a quick 1-2 gear run logged with the multidisplay, showing the lambda control for the first seconds (rich/lean cycle) and then rich during full throttle and lean when letting off.

on some VW´s we are running the LC-1 as a replacement for the narrow band sensor, with its 2 outputs (one programmed to simulate the narrow band for the ecu) and the 2nd to display it.
thats working quite well, all cars pass the emission tests  :)

having access to the gases it nice, would be nice to see how accurate for example the LC-1 is compared to a Bosch Ecu  8-)

Funky Diver

Jul 24, 2010, 12:15 am Last Edit: Jul 24, 2010, 12:16 am by Funky_Diver Reason: 1
Hey D2K2, I'm registered on your site, but it's easier for me here as your posts are all in English, lol (my fault not yours of course...Mein Deutsch  ist nicht so viel)

I was looking at hooking up a wideband on my carbed Scirocco to power a stepper motor or servo to give auto-choke.  Would you think that would be a good option?  Cheers,



yeah my site is currently a lot more german than english  ;)

the choke is needed during cold start or? wouldnt it be bether to get the temperature for this?
even a wideband takes some time to work, what i think could be to long to establish a stable running engine...


wow there is a lot of yummy data in that plot !!!

nice to see the output of the o² sensor is basically digital

that the throttle is really not spending any time in between closed and full open
you can even tell how good you shift was if there was a wheel speed sensor and knowing the transmission gear ratios
also you can tell how much boost lags behind rpm and throttle and how sharp your BOV response is

also it looks like your EGT is measuring more the exhaust pipe temperature than the exhaust gas temperature because that curve shows a lot of inertia !

I'd love to see a 20 minute drive downtown & highway video with this data superimposed, we could learn a lot about the car performance and driver's hability

hey also I think this project could be a very good general purpose data acquisition platform

something like this discussion was talking about http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1196965541/87#87

can you tell me more about this bosch ECU ? is it an OEM ECU made by bosch ? or a special aftermarket one made by bosch ?
do you have information about injector and spark timing and duration that could be superimposed on the data you just posted ?


Jul 24, 2010, 12:01 pm Last Edit: Jul 24, 2010, 12:05 pm by designer2k2 Reason: 1
this was a quick WOT run (wide open throttle)

i have no longer run from the current setup, but here is a older plot showing a lot more drive situations: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1239996764/16#16

wheel speed is on my todo list  ;)

im measuring EGT directly after the cylinder head (cyl 1-3 and 4-6 have their own sensor), and my water injection keeps it from jumping to high when hitting it  ;)

its a Bosch Motronic 3.8.1, standard ECU in the VW Golf 2.9L VR6
any data from it can also be logged (over OBD2)

and super imposing works too:

for the run up there i dont have the data for timing and so on, and i think my tuning shop would not be amused if i post them  :-X


I would guess he is definatly powering this via his car battery... :)

As for 5v, you should use a 5v regulator (search SparkFun), as well as a few caps with it to even out electric noise.


yes its car powered: http://code.google.com/p/multidisplay/wiki/Powersupply

use DC/DC converter, linear ones get very hot...

Jonathan Oxer

yes its car powered: http://code.google.com/p/multidisplay/wiki/Powersupply

It's good that you're taking extreme voltage variations (such as load-dump situations) into account with your power supply design, but I suggest you still replace the 7805 with an automotive-rated equivalent part like the LM2940CT-5. It's a drop-in replacement for the 7805, only costs a little bit more, and is designed to withstand the nasty voltage spikes you find in a car electrical system. I discussed the design of Arduino voltage regulators for automotive applications in chapter 15 of Practical Arduino so that may be some help.

By the way, it looks a bit like Multidisplay is very similar to several existing projects so you may be able to get some inspiration from them.

Freetronics: www.freetronics.com


im using this one: http://www.recom-international.de/pdf/Innoline-2008/R-78xx-0.5.pdf

i used a linear type before, but at 20°C ambient the temperature inside my enclosure got up to 60°C, with the DC/DC style ones there is no raise in temperature.

have you checked your list  for "dead" projects? for me only the MPGuino seems to be alive  :-?

Jonathan Oxer

Aha, cool, so you're not actually using the 7805 that's shown on the schematic or in the photos. I didn't know you were using something different.

All those projects should be active to some extent, although some aren't showing much activity because they've been around for a while and are beyond the early rapid-iteration stage. Some of the projects are several years old.

I can't speak specifically for any of the others, but the last link (the "vehicle telemetry system") is still being actively developed. I've added more to it since the book was published, such as the ability to write KML files directly to the memory stick: that's really cool because you can go for a drive, pull out the memory stick, plug it into a laptop, and open the trip file in Google Earth to do a 3D fly-through. The next thing I'm planning to do is get it to manage its own Internet connection without requiring me to have the Alix-1 running in the car and sharing its 3G modem.

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