injection sensor from an AAZ pump used for a revcounter pickup????

[Vincent Waldon]

I'm using an AAZ with the electronic advance in my mk2 conversion.

And just to be clear... you're talking about an AAZ pump with the electronic timing control down at the bottom of the pump, as per aidans' third picture, as opposed to the more usual "retard the timing slightly" control bolted to the side of many AAZ pumps... one that looks more like a stop solenoid?

Only asking cause there's tons of variations on these pumps....  ;-)

[markb]

I'm using an AAZ with the electronic advance in my mk2 conversion.

And just to be clear... you're talking about an AAZ pump with the electronic timing control down at the bottom of the pump, as per aidans' third picture

yep, that's the fella.

[aidan]

Nope, in my setup only the fuel cut-off solenoid has 12V on it.

Well I did have to leave my glow-plug switch on for slightly longer than usual, but still no problem.

(By the way - I agree with the others... Turbo it - who wants an auto anyway!)

There is always the option to turbo it (and incidentally, on the block it is stamped 1.9D / TD, so must be the same bottom end at least), but I want to get it running first and have the major obstacle of what starter to use, as the petrol one is too weak.

[regcheeseman]

is this the one you speak of reg?

Indeed that's the one - yellow and green wires. Do you know it's output and switch pressure?


I've run AAZ's with all this carp disconnected except for the stop solenoid and if anything, the power at low revs was improved.

[aidan]

Dragging this back up,
I've been informed the petrol rev counter is driven by -ve pulse.
Now assuming its 2 pulses per revolution, and matches the 2 pulses given out by this injection sensor, then how could we work it? Other than a relay switched by the 5v output of this sensor, switching the -ve to the rev counter? I don't think a relay would actually be suitable, surely won't be fast enough or long lasting

[Vincent Waldon]

Gasser tach signal looks like this:



Given that the output of the Dakota Digital converter is a 12V square wave (iirc) there's a very reasonable chance that the gasser tach could be driven by a 5V square wave just as easily.  If not, a generic switching transistor (2N2222, 2N3904 etc etc etc) could do the conversion to 12V.  A diode and capacitor could be added to give a falling pulse train if that's whats required as well, but my guess is that the square wave output will work directly.

[aidan]

Wow thats way over my head!!
If you or anyone can tell me how to do it I will try it. Will try it at 5v and 12v if necessary, I just have no diagrams for the petrol model so don't even know which connection on the coil is for the rev counter

[smutts]

Good stuff guys, I love homebrewed engineering like this. Diesel Timing Strobe here I come!

[truckinwagen]

this is all great in theory, but some of us need to get our hands on some of these injection sensors first.

[Vincent Waldon]

I just have no diagrams for the petrol model so don't even know which connection on the coil is for the rev counter

Yeah, a bit of geek talk...sorry... can't help it sometimes.

This:

http://www.a2resource.com/electrical/CE2cluster.html

shows which wire on the cluster the tach signal comes in on... experiment 1 would be to connect the output of the pressure sensor directly to the cluster and see what happens.

[aidan]

Not geek talk, I should know more about electronics before messing with things like this!

I will try this tomorrow or Saturday depending on if I have a day like today again.

Got a wiring diagram now -http://projectt4.t35.com/T25/1Yengine.pdf
It is Injection Period Sensor G175, on 2nd page.

Green/white from the sensor to the green  off the coil (to the rev counter). Whats the chances the sensor doesn't work now!

[regcheeseman]

It may be of some help but when I test/cal my tacho conversion on the bench they seemingly have to have 12v signal.

I've only noted by accident as my new fuction generators lacks the 'nuts' of it's predecessor.

They are not picky about waveform/ duty cycle or whatever but lack the amplitude and you just don't get the full scal deflection - I need to hook up to a alt to confirm that it is the func gen and not my circuits but I've got two on test that exhibit the same behaviour.

Good stuff guys, I love homebrewed engineering like this. Diesel Timing Strobe here I come!

Doubt it very much, the signal will not be accurate enough and wander around. It will also be hard to cal.

Should be fine for rotational speed and 5V is perfect.

[aidan]

The battery I need to test the car with is dead and can't get booster til tomorrow. The tach wire on the coil (green) is in a plug with a red/brown wire.
I will hopefully be able to get the car turning over at least tomorrow, but still wondering about the other information that I had, that its a pulsed negative? That would imply to me in my extremely limited experience that the tach has an igntion 12v supply direct to it.
Just concerned about damaging either the cluster or the injection sensor?

[regcheeseman]

The sensor is the one in the top of this pic with two wires

Yup, that's the exact page from the Yellow Jacket.

Fed with 12V but sends out a clean TTL-level 5V pulse for the ECU to process.

You really sure about this? Seems odd to have one wire supplying a 12v feed and the other giving a 5V out.

Common sense would say this is nothing more than a normally open pressure switch. Very unusual to have signal conditioning in the sensor body.

Any idea which wire might be the 12v feed and the 5V out?

[Vincent Waldon]

Actually pretty common to do signal processing on analog signals in a noisy electrical environment... like industrial plants or under the hood, and 5V is the industry standard signaling voltage.

It's an analog signal internally (from a piezo transducer) for a variety of possible reasons, starting with how difficult it would be to make mechanical contacts accurately switch at a precise pressure and 4000 RPM (8000 switch closures per second.... er....minute ) for decades.

The Yellowjacket says that the yellow/white wire is the supply line (+12V) and the grey/white wire is the signal line.