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CPS different for Manual??

mrtosh

NAXJA Forum User
Location
Woodbury, MN
Just wondering if a CPS would be different for a manual transmission. I saw they listed two different ones on the checker web site(one for each tranny). Autozone says "one size fits all"??
 
I can vouch that they are the same for the Renix as I'm using the original manual one with an auto. They are different between Renix and ODBI, though. Might this be one of the rare times AutoZone correctly looks up parts?
 
They break at 1990/1991 (later version is a Hall-effect switch, I'm not sure how the earlier version works...) but they should be the same between transmissions. Haven't gotten that far along just yet, tho...

This is exactly why I'm working on Swappology - I'm seeing entirely too many of these questions.
 
There are two different Renix era CPS's. Normal and high altitude. As for differences between trannies, like was said, they are the same.
 
Not to diverge from the original question, but I'm curious as to what the differences are? I never noticed any differences in operation from sea level (where I live) and the mountains.
 
I think (and Tom can probably correct me on this!) that the HA RENIX CPS has the sensor tip "advanced" two or three degrees to start the burn earlier (and I may have this reversed at the moment...) which is supposed to help compensate for the paucity of air at altitude.

I've driven RENIX XJ's across the country (back and forth from SJC to IND, and from SJC to ATL once) and didn't have any trouble at all going through the Rockies, the Sierras, or through Denver - so the utility of the thing is a bit suspect to me anyhow. However, I'm sure there are those that note it - and this would probably be the only real "failing" of the RENIX system (in my mind...) if it can't effectively and consistently correct for altitude with the MAP sensor and IAT giving air density readings anyhow.

Still others have reported a "butt dyno" increase in power from using the HA CPS at MSL, due to the peak burn/combustion pressure being closer to the peak leverage of the crankshaft/connecting rod assembly (12* ATDC, as I recall.) Again, this isn't something I'm worried about, so I've not dug into it. And, since I've not got an engine set up on a dyno, I can't quantify this effectively anyhow.
 
Yes it does move the sensor a few degrees towards the advanced side. When you drive a lot at altitudes above 5000 feet, you need to advance the timing. The old rule around here was to add 6 degrees. I helps to keep the emissions down and to give you a touch more power.

All that said, the Renix automatically adjusts the timing forward until it senses a ping via the ping sensor on the block, then it backs off until it just quits pinging. This works well, but when you get up to 10,000 like many of our passes, the computer can't adjust it enough because adjustment is a given maximum number of degrees from the point of the sensor. By moving the sensor, you gain a further range of adjustment.
 
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