944 DME Project

[George Elliott]

Tom, had a look at the oil pressure warning light again, it may be of interest to you.

if I start my car, watch the pressure rise to 5 bar, and switch off to stop the engine, and immediately switch back on the ignition, and watch the oil pressure dwindle away on the guage, the warning light at the bottom of the oil pressure guage comes on as the needle registers about 1.5bar.

never noticed before and never thought about it until the subject came up here - still its only a detail in the scheme of your plans

hope things are still going well

George
944t

 

[barks944]

Seems like there's no need then. Yep thing are good, tested the speed sensor circuits yesterday and they work perfectly. That's the last piece of the puzzle time to get some made...

 

[barks944]

Got a date for the first production board. Should arrive around the 16th of May when I get back from holiday. Cant wait!

 

[barks944]

Got some new toys last week!

Heres the new board on the left next to the original DME.

Another one with it closed up.

Really pleased with how its come out, it fits perfectly and the quality is very good. Now for the testing and enough programming to make my eyes square .

 

[944Turbo]

Very nice work!

 

[os951]

Tom,
oustanding job ! Looking forward the results []

 

[barks944]

Spent a good day on the system on Sunday and I am pleased to say the system has started and idled my 944's engine! Just waiting for my MAP and air temp sensor to arrive then I can really get stuck in!

 

[os951]

Tom,
any idea when 951 version will be tested ?

 

[barks944]

Soon I hope, the core code is the same as the lux which i am testing now. I hope to have my turbo back together in a few weeks.

 

[944 man]

Tom, Id really appreciate a summary of this (specification, features, projected availability, cost etc), if you dont mind?


Simon

 

[Frenchy]

Brilliant Stuff, any probs with DME.................Call Barks !

 

[barks944]

ORIGINAL: 944 man

Tom, Id really appreciate a summary of this (specification, features, projected availability, cost etc), if you dont mind?


Simon

Spec wise the current board supports the following:

[*]Wasted Spark Ignition
[*]Fully live re-mappable via USB without piggybacks
[*]Air Flow Meter replaced with TPS, MAP and or MAF
[*]Bluetooth interface to mobile phone
[*]Datalogging
[*]EGT Monitoring
[*]Closed Loop AFR Control
[*]Knock Input
[*]Integrated Boost Control
[*]Easy to use diagnostics with fault memory
[*]Simple installation

 

[George Elliott]

Tom, is the FQS included on your pcb, or is it made obsolete by closed loop Knock/Boost/AFR controls?
Also, how does your system cope with fuel injector impedence, I understand the original ecu is fragile in this area?
WUF operated on slightly higher battery voltage (standard plus half a volt), and a long time ago, inspired by this, I added an adj voltage reg to my 951 alternator, and set the volts to about 14.8v. My electric windows flew up and down, dash illumination was excellent, headlights (tested it at night obviously) were like xenon's, the engine was "crisper" less laggy, but at around 6000rpm after 5 miles, I blew the sci-vision maf sensor[8|]. But I wonder, could you make this board cope with a higher voltage level? The rest of the car would benefit enormously. If you can, I hope to be your first customer in Ireland.
and as others have commented, an amazing bit of work.
George
944t

PS; WUF was a car[]

 

[barks944]

George,

The FQS is now redundant and does not exist on my board. It was really just a coarse fuel adjustment necessary in an age when usb tuning wasnt possible. With this board you can control all fuelling/ignition settings via usb and it should also be possible to used closed loop AFR control using a wideband/narrowband sensor.

The circuits that drive the fuel injectors are just designed to handle low impedance injectors. This is simply the resistance of the coil winding in the injector. I'm not aware that they are fragile just that they are designed to operate injectors of a specific impedence, one that is not that common. Although there are plenty of upgrade options these days, so I don't think its a problem. This system retains the original fuel injector drive circuits.

The reason your MAF blew will be because it was operating directly from battery voltage and when at 14.8V this must have been too much for it. I do not actually think that a MAF will be necessary with this system and I intend at this point to use MAP/TPS/Air temperature. The system calculates air density continously and uses manifold pressure to calculate the mass of air in the cylinder. It then calculates the mass of fuel required to achieve the desired air fuel ratio taking into account the volumetric efficieny of the engine at the current load site. Essentially tuning the VE is how you get the fuelling right at a given load site. It can do this so fast that it can update fuelling and ignition parameters within a single stroke even at max RPM. It also has much higher ignition accuracy than motronic which is only accurate to 0.7 degrees. This system will achive better than 0.2 depending on how I code it. Anyway the to get back onto the original point, because I don't need MAF I can use a 5V map sensor which will never see the 14.8V of the battery as it has a 5V regulator. Assuming the rest of the original DME power board doesn't mind 14.8V it should be ok. I can do some tests to ascertain this. The added benefits of a higher voltage will also be a shorter dwell time and reduced injector dead times.

Hope that makes sense!

 

[JarmoL]

This looks seriously amazing..[8D]

 

[Jonny944CS]

Loving your work Tom, very impressive.

I look forward to seeing it all come together.

 

[George Elliott]

Tom,
yes, thanks - it is clear. I look forward to seeing it progress.

regarding my earlier comments, I guess I need to be cautious with the voltage reg setting as I dont want burned out wiper motors or fuel senders or instruments etc. On the other hand, you seem to have spotted the reason for the crisper (especially off boost) engine response with the spark behaviour. All I can say is it was very noticeable.

As you have made the AFM redundant, perhaps the snorkel / intake / filter unit can be revised to open up the intake under the chassis leg as opposed to the standard constricted setup.

It appears you may have made many of the "band-aid performance systems" which, intercept, piggy-back, massage, supplement, override, - the standard basic system redundant. Lots of cars including my own have these and produce more power, but its great to see a clean sheet ECU using todays technology to optimise the true potential of the 951.

good luck with the next steps
George
944t

 

[barks944]

Thanks for the kind comments guys, much appreciated [].

It is interesting what you noticed with running a higher battery voltage. I hope to be able to get the same benefit by using a wasted spark system which will drop the dizzy and shorten the overall length of the HTC lead from the coil to the plug.

With regards to the intake, it is something I will be taking a good look at. I have a very good local aluminium fabicator who does a lot of intake systems for dakar rally vehicles. I will be having a chat with him shortly about possible options. The basic idea is to make a pipe to replace the AFM and this will both have a screw in location for the temp sensor and a mount for the MAP sensor. This would retain the standard airbox though.

 

[George Elliott]

Tom, keep us posted ref the airbox, I like the OE look, but The snorkel strikes me as restrictive. Porsche more or less admitted this with the 968t when they chopped it, especially challenging for them with the extra cc's.
George
944t

 

[barks944]

Running pretty good now

http://www.youtube.com/watch?v=DqhIvPIVauI

Edit: just uploaded a new video.