Raceboy

This is the best pic I have right now.

Raceboy

So, I had a road-trip on Friday with the beast and did some datalogging together with some tuning for economy. On light cruises I set the mixture to 14.6-15.3 depending on rpms and that old 2valve 928 really surprized me getting 8l/100km on highway (~100kp/h average speed). It should be around 28-29mpg?
I found it a bit challenging finding a good spot for overrun fuel-cut and resume rpms, because on usually good value of 1800rpm both it started to act weird on light loads by cutting and resuming fuel. Investigated the problem also. It appears that 928 needs too little accelerator pedal for light loads and ECU assumed it's the TPS=0 situation Anyway, I ended up calibrating the lower TPS 0 spot to lower value and setting fule-cut point to 1800 and resume point to 1100 (idle is 750rpm) so it recovers very nicely while on city driving this feature saves A LOT of fuel.

plastex

I am looking at doing a Megasquirt setup on my 83' and was wondering if you used the stock injectors? Also, are the injectors Low impedance?, and how many pounds are they rated at?

I ask this because if I can use the original injectors my install will be a breeze. I want to set it up initially to just monitor all the signals that I hook up and finally plug the injectors in and run it. This way I will have the ols system in place. When I did my 76' 911 with CIS using megasquirt it was a pain in the butt cause I had to use difft injector bungs/airbox/ and everything.

Thanks
Oscar

Raceboy

Yes, injectors are original, they are high-imp. As for capacity, I don't know exactly, because on VEMS install it actually doesn't matter (you can set req. fuel constant as you like and play with VE table instead or in contrary). It should be the same with MS. Stock injectors should be somewhere in 240-250cc/min range.
I suggest you to install all at once, why bother with "intermediate" setup? I did VEMS conversion on my CIS 924, and was more than pleased to ditch all that crappy stock FI and ignition stuff away.

But, with MS I suggest you to investigate how to use stock 100-1 trigger wheel, perhaps some additional wheel decoder or something is needed.
But it definitely makes the install a lot more cleaner.

plastex

I am going to have to look back at my notes on how I set up the 76 911 that I did because it did not have any trigger wheel at all. On the CIS it didn't need it. I am not sure how I set that system up, but plan to do this one the same.

Oscar

Raceboy

Do you have CIS on your '83? If so, you'll need a trigger wheel, either simple trigger (at least 4 notches on crank pulley 90 degrees apart) or 60-2 or similar. But, just in case you could check your flywheel, maybe, just maybe it has trigger wheel there.
MS can also utilize signal from the ign. coil but that is definitely NOT RECOMMENDED.

Your best way is to install trigger wheel if yours don't have one and going with two 2x2 Bosch Motorsport wasted spark coil-packs ( part#: 0 221 503 407, dtasheet is here: http://www.bosch-motorsport.com/pdf/..._coils/2x2.pdf )

SwayBar

Great thread; you obviously know what you're doing! What is your background?

Did you dyno the car after the installation? How long did it take you to dial it in?

Raceboy

I'm actually a 28year old journalist in a car magazine by a profession and finishing my university studies (journalism, major is digital divide and the social backround of it)
As my second job (kinda hobby) I install and tune engine management systems and my real hobby is Porsches.

It took half an hour to get drievable map but it took 2 mornings to get the cold start and afterstart enrichments right. We haven't dynoed it yet but we compared it to bone stock but refreshed '84 Euro S (both are autos) and we got a 2-car length lead at 1/4 mile, repeatedly. So I guess it runs a bit better.
We plan dynoing after exaust work and ITB intake install. Right now the car gets a new paintwork so it's going to be after that.

BC

Are you finding more support available for VEMS now or is it still a "You figure it out" deal unlike the heaps of support MS has?

FlyingDog

Stock injectors are ~24lb for all LH 2.2 928s.