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Question on CPS Tooth/Notch Patterns on Renix 88XJ Flexplate

CJR

NAXJA Forum User
Location
PA
I have seen two(2) different tooth/notch pattern on the Renix XJs that are used to generate the CPS voltage spikes. One flexplate pattern has three 120 degree sectors with three large notches separating each sector. Between the large notches are 20 small teeth. Supposedly, the ECU counts the small teeth and knows that TDC is at 12 teeth. Each large notch represents two (2) pistons moving in the same direction, i.e. 1 & 6. The sync generator, in the distributor, then tells the ECU if the piston is 1 or 6 in order to fire that cylinder..

The other flexplate pattern to generate the CPS voltage spikes has a large tooth followed by a large notch followed by the 20 small teeth. Supposedly, the larger tooth and larger notch causes the CPS to send a higher voltage spike to the ECU than the smaller teeth spikes. Higher spike voltages tells the ECU that a piston will soon be a TDC, 12 teeth later.

Did Renix use different ECU configurations for the two(2) different CPS patterned flexplates? Or can we use either flexplate CPS pattern with any version Renix ECU?

Best regards,

CJR
 
Looking at where and how they are mounted, I got the idea, right or wrong that the CPS is looking not at the teeth at all, but at the windows on the round band that the tip (the magnet) is actually aimed at?

The teeth are what the starter motor uses for leverage to turn the engine.

I know that most posts and write ups talk about teeth, But my visual inspection of the stuff several times over the years has me doubting it is the teeth at all as the seem to off to the side of the sensor tip and the magnetic field is aimed down at the ground I think???

Be curious to see what cruiser54 and Old_man think.

Also I think putting washer-shims behind the CPS bracket, between the bracket and the Transmission bell housing may be the real trick to boosting cranking voltage. I have tested the theory by bending the bracket so it bows out, just a little, and it doubled my cranking voltage.

Now the Manual transmission plate may be a different story? He is the Flex plate

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This one is a 91-? HO manual plate note the notches!! Versus the teeth the starter gear uses and eats/chews up over time.

s-l225.jpg
 
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All Renix use the same pattern, regardless if it is manual or auto. The HO uses a different pattern than Renix but again it is the same for manual and auto.
 
Thanks everyone for responding. I thought I was missing something on my Renix system. Bottom-line is that the Renix only uses a "shutter-type ring" mounted on the flexplate to trigger the CKPS, while the HO engine uses notches machined into the flexplate to trigger the CKPS .

Best regards,

CJR
 
Thanks for confirming my theory. There is a thread about a crank shaft has 3/8" of movement, bad thrust bearing/crank, that still starts. Those windows are huge, LOL. But now I think I am right that the cps could be moved towards the rear to boost the cranking signal strength!!! The windows are too far to the rear on a stock jeep.

Thanks everyone for responding. I thought I was missing something on my Renix system. Bottom-line is that the Renix only uses a "shutter-type ring" mounted on the flexplate to trigger the CKPS, while the HO engine uses notches machined into the flexplate to trigger the CKPS .

Best regards,

CJR
 
The only way to increase the signal strength reliably would be to move the sensor closer to the ring. Just don't let it touch.
 
The only way to increase the signal strength reliably would be to move the sensor closer to the ring. Just don't let it touch.

Well I already proved that to be wrong, twice, on 2 sensors. I moved the probe back towards the rear about 1/16" max and the cranking voltage output doubled on one and tripled on the other. From .16/.27 up to .51 on Volts volts cranking AC

I think that the sensor tip is too close to the edge of the holes, and scooting it back towards the center of the hole is why it doubled.
 
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The only way to increase the signal strength reliably would be to move the sensor closer to the ring. Just don't let it touch.

Stock, on the flex plate version there is about a 3/8" gap tip to the hole ring surface so it would take some serious remounting work to get one close enough for it to hit.
 
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