Output questions

[stevesingo]

Hi Folks,

I am in the process of planning an install of M800 in to an E30 M3 (1990) and would like to figure out a few functions.

1, I have a oil temp sender (bosch) connected and intend on logging oil temps. Can I use a PWM Aux Output switched to earth, effectively emulating the stock senders resistance to earth, to give me a reading on my oil temp gauge?

2, I have a Carbon Canister purge Valve which on the stock ECU is energised for a period of time (60secs I think) on start up and then remains closed until the next start up.

3, The Valve is fused and has a resistance or 23.5ohms, so shouldn't draw any more than 1amp. Should I use a relay?

Many thanks

Steve

[Martin]

1, I have a oil temp sender (bosch) connected and intend on logging oil temps. Can I use a PWM Aux Output switched to earth, effectively emulating the stock senders resistance to earth, to give me a reading on my oil temp gauge?
Steve

Ive tried this, it works. You will have to try different frequencies to keep the gauge from whining. Im not sure how long the gauge will last. I think you can add some electronic components as a damper to the gauge.


I think 23 ohms is well within the limits of the AUX outputs. If you want to stress them less use an INJ output or AUX 1 or 2.

[stevesingo]

1, I have a oil temp sender (bosch) connected and intend on logging oil temps. Can I use a PWM Aux Output switched to earth, effectively emulating the stock senders resistance to earth, to give me a reading on my oil temp gauge?
Steve

Ive tried this, it works. You will have to try different frequencies to keep the gauge from whining. Im not sure how long the gauge will last. I think you can add some electronic components as a damper to the gauge.


I think 23 ohms is well within the limits of the AUX outputs. If you want to stress them less use an INJ output or AUX 1 or 2.

Martin,

Thankyou.

I was planning on using a Inj output for the canister purge anyway. What is the best way to set a timer on this for say engine start plus 60 secs?


Frequency wise I was gong to start high (5000hz) and see what happens.

Steve

[Martin]

5000 is too high, you will need excessive DC to drive it to a certain position, The lower the freq, the higher it`ll lift for the same DC. I think you`ll end up with 200Hz and up.

For a canister purge valve you should not run it just time based. You should have a vacuum parameter in there as well. I would suggest you use a closed throttle timer and manifold pressure in an AUX table. You could run it for a few seconds every time you close the throttle and its in vacuum. You need vacuum to clear the canister of vapour. If the car has a canister purge valve im sure the fuel tank will be fitted with a pressure sensor. Maybe check if its got one and wire it up to the M800 to control your purge valve as well.

[Dragon]

What crank triggers will you be using?
I tried using the standard one at the flywheel. It did not work out.

[stevesingo]

I am using a 8 tooth crank trigger, that is currently in manufacture. Cam trigger will be S38B38 M5 hardware.

Steve

[MarkMc]

Hi dragon,
We have used a few different variations of the type ofcrank trigger found on the E30 (Porsche 944 as well) and they work fine, they can be a little fussy to set up though.

What problems did you have?

[stevesingo]

Mark,

I'd be interested to hear your suggestions on how to use the original engine speed and cyl id sensors on the flywheel, plus a sync sensor for sequential. That would be neater for me.

Steve

[MarkMc]

The factory setup has the sync on the flywheel (group fired only) and the ring gear teeth for the ref. This works because the ref and sync are mechanically locked together but unfortunately is ony for group fire. If you want a sync on the cam/distributor and use the flywheel teeth you will have a problem becasue the tow are not mechanically locked together, there is a little slack between them. Sorry i may have suggested it was possible, I should have made it clear the factory stuff works well for group fire only.

If you want to run the engine sequentially you need the cam/distributor trigger and something on the crank, I would suggest 12 evenly spaced teeth on the crank or 36-2.

[stevesingo]

Thanks Mark.

Well I didn't think sequential was possible with the standard flywheel sensors, but you kind of implied it was.

No worries, as I'm using a 12 tooth crank trigger and a cam sensor anyway.

Steve