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Old 01-06-2010, 12:09 AM   #123 (permalink)
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ECONORAM - '07 Dodge RAM 1500 QC SLT flex-fuel
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Originally Posted by dcb View Post
Update, sorry this didn't sink into my head till now, but on the metro at least (and probably many other cars) YOU ONLY NEED TO INTERRUPT THE CAMSHAFT SENSOR CIRCUIT. I just ran some real world tests to confirm this. This would be a good wiki thing.

Let me explain,

interrupting the camshaft sensor tells the computer that the engine is now doing 0 rpm. The computer responds by sending out an ignition signal appropriate for 0 rpm AND an injector signal appropriate for 0 rpm. In other words, it stops both the ignition and the injector.

I confirmed this by monitoring the mpguino instant injHIus while coasting in gear while pressing the camshaft circuit interrupt kill switch. when I hit the switch, the injHIus would go to 0 even though the engine was still turning over via engine braking. I believe the ignition is also being killed because the car shuts down cleanly but havent confirmed with an actual test (i.e. play with the timing light and the kill switch).

So the actual circuit could just be a normally closed switch put in series with the camshaft sensor.

Other cars might be different, that is where the wiki would be useful.
Hmm. Very interesting. I have been thinking about this for my Dodge RAM. A fuel cut-off for downhills would be great, especially since my truck's dogamatic will downshift if the cruise control is engaged and I go down a hill...
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