Data Logging on a 944

tref · Jun 10, 2009

Gentlefolk,

Having finally got round to jubilee clipping a thermocouple to my exhaust manifold, I now have some idea of the temperature it is running at (somewhere between 350-450 C typically, on the branch from No. 1 cylinder). I have also discovered that the meter has the facility to export data to a PC (RS232). Trouble is, temperature against time doesn't really demonstrate a lot, and at the moment, is about all I could collect.

Anyone know how easy/expensive it is to extract other information from a 944? In this case it is a 1990 or 91 S2. Ideally it would be road speed, engine revs, and throttle position... I guess engine temperature would be useful too...

For reference this is to get some background data before I switch on the LPG (which is still some time away, but hey - it gives me more time to collect data).

zcacogp · Jun 10, 2009

Watching with interest - this could be interesting.

If all else fails (and I suspect this could be the way you end up going), you could add extra sensors and take data from them (RS232 or other protocols). I have recently seen some very neat little data-logging memory systems that capture data over a period of time, running from a 1.5v battery. You leave them in place for as long as necessary (or until they are full), and then take them in and download everything via USB into a PC. Small enough to be fitted into a film canister, too. A friend was using them to log weather patterns from a home-rigged weather station in his garden.

Although ... on Pistonheads recently there was posted a video from Brett Ainley, about the technical aspects of the nitrous install on his 928. Let's not go there in terms of opinions, but it was clear that he had a quantity of real-time data from the car wired into the nitrous system, and I think it included (at least) engine revs and the gear the gearbox was in. Could have had road speed as well. I'm sure he would be happy to help you out, but you may find some other project preferable before you got to that degree of desperation ...

Keep us posted with the LPG install.

Oli.

Flick · Jun 10, 2009

'Consult' Brett? That thing is a grenade with the pin pulled and an idiot juggling it about.

There are other avenues to be explored before that one.

944Turbo · Jun 11, 2009

Most widebands have the ability to datalog several parameters, might also be usefull for checking the mixture when the gas is in - though IIRC there are different values for lpg/petrol.
Tony

944 man · Jun 11, 2009

When I read 'Brett' and 'consult' I immediately think of a chaise lounge.....[

]

You have to wait until the late nineties for Porsche to adopt the OBD standard. Im not aware of any aftermarket ECUs that support it, although they might. Some have their own proprietry software thatll give you the same information though: MegaSquirt certainly does:

No exhaust gas temperature, but this isnt going to be found via an OBDII port either and if you know the AFR, then the exhaust gas temperature isnt going to be too important on a normally aspirated care, surely?

Simon

tref · Jun 11, 2009

Thanks Oli,

Can you tell me more about the data loggers you have come across? Sounds ideal. If necessary I am sure I could rig another hall senser to pick up from the flywheel, and tap into the speedo signal some-how.

Brett is an ex-member of our region, and I have experienced his 928. Indeed I am sure he would be happy to help, how-ever, there may be a slight discrepancy in budget... put it this way... one man filling with Nitrous, the other filling with LPG[:'(][:-][

]

tref · Jun 11, 2009

A few missed posts there - thanks guys.

Since I understand the fuel/air ratios are indeed different for LPG to petrol, ensuring exhaust gas temp doesn't increase dramatically seemed the easiest check that all is well, hence my first step has been getting some back-ground temperature data. OK, strapping athermocouple to the exhaust manifold is hardly ideal, but better than nothing - I'm looking for changes rather than absolutes.

If I look at using an AFR meter with extra logging capabilities can I piggy-back from the existing Lambda sensor?

JamesO · Jun 11, 2009

The Vems wideband controller I use will log afr, rpm, map and exhaust temp ( or any temp you want to log) but you need a laptop connected to create a log.
Google VEMS.
I believe it will provide a narrow band output for the ecu if you replace the narrow band in the exhaust for the wideband sensor provided.

I used it to log afr, intake temp, map and rpm.

944Turbo · Jun 11, 2009

ORIGINAL: tref

If I look at using an AFR meter with extra logging capabilities can I piggy-back from the existing Lambda sensor?

You would need a wideband sensor for a wideband logger - the standard sensor is narrow band 0-1V wideband is 0-5V.

most widebands need a pc to download the data, so if you need a laptop in the car anyway, suddenly thought about this

http://www.maplin.co.uk/Module.aspx?ModuleNo=42857

Might be useless - depends on what you can do with the software, off the shelf wideband would certainly be easier.

I have an innovate wideband, but as I still haven't got around to fitting it cant comment on the logging.

Tony

JamesO · Jun 11, 2009

Forgot to add the vems unit will work from the tacho out of the ecu and any K type thermocouple.

Megasquirt/microsquirt will log anything but again you will need a laptop in the car to log.

944 man · Jun 11, 2009

I have a touchscreen industrial PC, with MegaTune installed; ready and waiting to go..... [

]

zcacogp · Jun 11, 2009

ORIGINAL: tref
Can you tell me more about the data loggers you have come across?

Sure - I'll eMail the friend with the weather station and see what comes back.

I'll post up the answer here.

Oli.

Peter Empson · Jun 11, 2009

I use the Innovate Motorsports LMA-3 for my application, I can log boost, EGT's, A/F, even acceleration (irrelevant for me but it comes as standard) against rpm, and other paramaters as and when I want to expand it. The only downside is you need a laptop connected, so without coming up with a clever mount for it I can't see what's happening during a track session (they do more expensive ones with internal data storage for this use). It's not the most intuitive stuff to use, but it is quite reasonably priced.

944 man · Jun 11, 2009

Pete, for your application Id suggest an early tablet PC, which can be bought for peanuts off t'eBay. Theyre touchscreen, have a serial D-sub and because they cost so little you can adapt them into the vehicle without worry.

Something like this: http://cgi.ebay.co.uk/RM-TABLET-PC-RTAB910-T01-WIRELESS-XP-PRO-TABLET-EDITION_W0QQitemZ220428766995QQcmdZViewItemQQptZUK_Computing_Laptops_EH?hash=item3352940f13&_trksid=p3286.c0.m14&_trkparms=65%3A12

...would be more than up to the job Id have thought.

Simon

Peter Empson · Jun 11, 2009

Cheers Simon, that's a really neat solution. I've got a small Fujitsu lifebook touchscreen which I use, I have looked at making a bracket to attach to the passenger seat side mounts which is possible, but to be honest I figure that if I haven't got everything optimised on the road/dyno by the time I get it to the track then it's probably too late to worry anyway!

John Sims · Jun 11, 2009

You can tap into the DME and KLR to extract more data:-

KLR#22 (white/green stripe) TPS
DME#7(green/red stripe) Air Flow
DME#21(light green/black stripe) RPM
DME#17 (brown/yellow stripe) GND
DME#18 (red/yellow stripe) +12V
DME#24 O2 sensor - if the car has one - if not the plug will still be in the engine bay so another useful link for something else - worked well for my narrow band installation.

If nothing else 17 and 18 are a useful power tap.

Exhaust gas temperature can be a very useful tuning aid but I don't know how effective it is based on external manifold temperature. The latent heat within the manifold will present latency [8|] in the data provided. It would perhaps be better to use an EGT probe in the manifold.

944 man · Jun 11, 2009

When the kit is disposable it become far more useful: and easier to mount! I bought an industrial 8" touchscreen PC to do the same job, but it was an ill-thought-out plan. In achieving durability through the PC104+ architecture, I also added well over 10 kilogrammes! Fail.

barks944 · Jun 11, 2009

You can use a USB data aquisition device (USB-DAQ) and a laptop. You can get one for about 100 quid delivered from national instruments. This will log a number of -10 to 10v signals.

If I put a pc in a car I would use the internals of a netbook and a touchscreen panel. You could connect it to a usb DAQ and have an in car data logger/gps/media/internet....... You could also control relays etc etc with the digital outputs for other purposes.

tref · Jun 11, 2009

ORIGINAL: John Sims

You can tap into the DME and KLR to extract more data:-

KLR#22 (white/green stripe) TPS
DME#7(green/red stripe) Air Flow
DME#21(light green/black stripe) RPM
DME#17 (brown/yellow stripe) GND
DME#18 (red/yellow stripe) +12V
DME#24 O2 sensor - if the car has one - if not the plug will still be in the engine bay so another useful link for something else - worked well for my narrow band installation.

If nothing else 17 and 18 are a useful power tap.

Exhaust gas temperature can be a very useful tuning aid but I don't know how effective it is based on external manifold temperature. The latent heat within the manifold will present latency [8|] in the data provided. It would perhaps be better to use an EGT probe in the manifold.

OK... DME 22, 7, and 21 are probably most useful to me... so if I tap into that, what is the best (read cheap, and not likely to damage anything) method of getting the information from said wires into a computer?

I'm ok with having a lap-top running in the car - it is to gain background data and set up rather than anything permanent, and I don't need to read it whilst driving... indeed, probably better if I don't or I start playing silly games like "lets see how hot I can get it "(full throttle up a steep hill in low gear - 465C before I ran out of hill). Rattling around in the passenger footwell is fine, which is what the meter is doing at the moment.

I agree measuring outside the manifold is less than ideal, but adequate for my application... I really just want to ensure the LPG conversion doesn't change operating parameters drastically in a way that could damage the engine.