python, i2c bus, a2d convertion, embedded, pre odb2, android, GPS, telemetry

@airportable - yes correct on all counts

@cairnsys - my understanding was that the 2j protocol was different tob1.9, but I've never verified that. I've got a VAG cable with the ftdi chip somewhere so will investigate.

I looked at MEMSDiag a while ago but as it didn't cover 2j I didn't pursue it, besides at that time the car was a flash way of getting a suntan or wet if you're on the M6 between services & it starts to rain. It's now a family treasure/money sponge (as opposed to money pit) & if it's another way of caressing it I'll look at that as well.

By the way slightly off topic, but if you keen on pi based projects and the like I publish a daily digest of stuff found on the web at https://paper.li/mug_pi/1522492367

I have a problem with extramural activities: I trend to be sucked into them to the exclusion of my core stuff, which is why I'm not G3???, anyway this summer job involves rebuilding the Land Rover. However I'll be putting the fine tip on the soldering iron when you start publishing your system. Mike.

I know that folk have grafted MEMS3 ECUs onto 2j cars & there are notes around that cover, to a degree, how this is achieved, however & if you are the author can I firstly apologise, they are a little difficult to decipher. What is needed is a how to for confident & talented soldering iron jockeys. Anyone up to it?

That's also interesting as a future project. I had thought about an emerald ECU a few times, but never got round to it.

I guess the mems3 should be fairly similar as far as most things go.... I imagine that you would have to fit the extra lambda sensor and there would be the issue of recoding the ECU to match the A5S security subsys.,. I'm just trying to picture all the differences between my vvc and ex-wifes late series TF...

Hmmm... More to think about.... So many projects, so little time!

In your earlier post you use the phrase “- - - - allows for some sensor data to be spoofed for test purposes ie feeding say a different lambda - - - -”, an elegant way of putting it. I believe you can arrange a network to spoof the ECU in to thinking it has a second lambda, I'm also told he A5S can also be duped.

Indeed. Basically as the ECU believes whatever it's sensors tell it, and this input is in the main just a 0-5v analogue voltage, it's not too difficult to get the ECU to alter the air fuel mix and by simply providing the appropriate voltage on the input pins. Air temp, manifold pressure and the lamda sensor, along with throttle position are the primary factors used by most ECUs to vary the fuel air mix to account for cold start and variations during running. Minor tweaks to these. Values might be used to temporarily reduce emissions at MOT time, or to slightly increase performance at the expense of emissions / economy. I certainly would not advocate this as an everyday activity, but if access to a Dyno was available, it gives opportunity to play what-if games on systems that are not readily re-mapable.

Basically it's about being able to experiment a little.

Playing with values up stream of the ECU prior to an emission test isn't a new concept, the German car industry have been at it for years. However as it's the emissions test that makes many a sphincter squeak at MOT time, to be able to switch in a predetermined value to lean up the mixture would, I'm sure, be a useful adjunct. A discreet switch under the dash marked “MOT pass/ full fat performance” would sell well on E-Bay, especially if it could be installed using double sided tape, cable ties & Scotch locks/terminal strip! Not that anyone on the T-Bar would be interested in such things; Heaven forbid.