Dave Robsons Challenger R/T

Post by **TyreFryer** » Sun Oct 05, 08 10:17 am

Seriously though, your making a superb job of that exhaust setup. Can't wait to see the car back out again.

Anonymous · Post by **Anonymous** » Sun Oct 05, 08 12:01 pm

Is it a three wire O2 sensor, in other words 'heated' ?

Make sure you run unleaded and be careful of many proprietary octane boosters as the lead can really foul them, especially if it is an unheated sensor. Before it lights off, the lead can stick to the sensor and cause degredation. Modern O2 sensors take a voltage and heat up very quickly so they go closed loop within seconds, unlike older single wire sensors that relied on exhaust gas temp to get them up to operating temperature.

Nice to see some high tech going on there, Dave, rather than the classic 'suck it and see'.

Dave-R · Post by **Dave-R** » Sun Oct 05, 08 3:38 pm

Yes it is heated Sandy.
In fact I hope it is not too close to the collector as these ones don't like to get too hot. They work well even just clamped up the tail pipe as long as there is no catalitic converter in the way as they can throw the results off.

Anonymous · Post by **Anonymous** » Mon Oct 06, 08 7:06 pm

Looking good Dave.

Them electronic cut outs look very swish.

Dave-R · Post by **Dave-R** » Mon Oct 06, 08 9:04 pm

I have got a vacuum map sensor from a mate and I am having trouble figuring it out.

I assumed that when vacuum is applied (sucking on the T-Pipe in the photo) the resistance of the sensor would change.

I think the Green wire is the 5 volt INPUT. The black is the output voltage to the LM-1 box and the grey is the ground.

But no matter which way i connect up the meter I cannot get any change in resistance when I suck on it.

Am I going about this the right way or is this just a dead sensor I wonder?

MetalChuckKey · Post by **MetalChuckKey** » Mon Oct 06, 08 9:55 pm

Is it really a straight potentiometer? Or is the sensor a powered item that you have to supply +5v to the green wire? Don't write it off till you've chucked a DC voltage across green to grey and measured the change in DC voltage on the black when you suck on the pipe.

mopar_mark · Post by **mopar_mark** » Mon Oct 06, 08 9:58 pm

Dave wrote:I have got a vacuum map sensor from a mate and I am having trouble figuring it out.

I assumed that when vacuum is applied (sucking on the T-Pipe in the photo) the resistance of the sensor would change.

I think the Green wire is the 5 volt INPUT. The black is the output voltage to the LM-1 box and the grey is the ground.

But no matter which way i connect up the meter I cannot get any change in resistance when I suck on it.

Am I going about this the right way or is this just a dead sensor I wonder?

Dave,
Rightly or wrongly, I would test the sensor in the exact way you are doing. Can't confirm the wiring colours ?

latil · Post by **latil** » Mon Oct 06, 08 10:01 pm

4Any idea what the sensor came from? There's quite a bit of info on the net and most makers use different colour codes.

Dave-R · Post by **Dave-R** » Mon Oct 06, 08 10:03 pm

I have checked all the possible combinations of connecting the meter. The resistance is different on two of the wires but still no change no matter what way i do it.

I will make the 5v power supply this week and try that.

Dave-R · Post by **Dave-R** » Mon Oct 06, 08 10:05 pm

It is a mopar sensor.

It could be a solid state device that needs power to work. So I will try again when I have voltage.

Dave-R · Post by **Dave-R** » Tue Oct 07, 08 12:49 pm

Went all the way into town at the start of my lunch break to buy everything I need to make the 5v power supply.

Maplins had all the components in stock. The guy got them out and packed them in a little bag for me.

I put my hand in my pocket and no wallet.

I had it in my other jacket last night and must have forgotten to swap it to this jacket.

I hope.

Oh well. I will make it tomorrow then.

Matt · Post by **Matt** » Tue Oct 07, 08 2:02 pm

I'm with Chuck Key on this .

My best guess :

You won't see much at all without giving it its 5 volts.

If it's an active sensor you're not looking for a resistance change .

You'll see a varying voltage on the output terminal.

Dave-R · Post by **Dave-R** » Tue Oct 07, 08 2:22 pm

Fingers crossed.

Dave-R · Post by **Dave-R** » Tue Oct 07, 08 8:56 pm

Yep. A mate says I need the 5v on for it to work. The voltage will go down with vacuum.

Yeah Dave, you need to connect it to a steady 5 volt DC source. ...Keep me informed, I am interested in seeing how this works. It should work like a charm! One other thing, I studied the wire diagrams again and the ground wire,(grey), branches off to a common ground. meaning, if you connect the meter to the grey wire and you get no readings, try connecting to the grey wire and a common 'grounding' source along with it.

Dave-R · Post by **Dave-R** » Wed Oct 08, 08 2:54 pm

Not made a circuit like this for 25 years.

But it works!

12 volts in and 5 volts out.

Now I just need to test the vacuum sensor with it and see how much current this thing pulls. Also to see if the voltage output from the sensor matches the pressure scale I have worked out. 5v should = 1 Bar (30 inches Hg). Don't think I can suck that hard though. I am no George Michael.

So I have a scale worked out for the lower levels of vacuum.