Installing and correctly setting a vortec distributor

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Aloicious

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yeah cmp is the cam retard offset, but its different than the actual timing advance value.

the advance shows the computer controlled timing spark advance for the spark, the spark advance that you see in that pic will vary based on RPM and airflow from the PCM's spark map and other calculations from the PCM, since the spark advance is fully PCM controlled in the vortecs, reading that value from the scanner won't help you set the distributor at all.

the CMP retard offset is a reading of the CMP sensor that detects the offset of the distributor position itself. which is what needs to be monitored while setting the distributor position. you want it at 0-2* at ~1000-1200 RPM....I'd go get a quick log and show you the differences on the same screen, but I no longer have a conventional distributor in my L31 anymore. the main problem is that the CMP offset sensor is so specialized from the 96-2002 L31 (and maninly only 96-98 in those years) that most general manufacurers don't support reading it. you'd need something very GM specific, and even then its not a guarantee. the ones that I know that can read it for sure are EFILive and a Tech2...I think HPT, one of the autoxray versions, and some specific snap on scanner will also read it, but I've never tried it with them.

thats a cool little live data reader for the phone though, what kind of OBD cable does that use?
 

SAATR

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SnapOn MODIS does support reading it. I've set quite a few with that little jewel, though I believe they have something newer and nicer out these days.
 

Aloicious

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yeah thats the one, I can never remember the MODIS name...Thanks!
 

Mrich0908

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Here is another discussion were having in another part of the forum,

http://www.gmt400.com/forum/showthread.php?10053-OBD2-Elm327-Torque-Pro

DGA1 There are tons more programs besides TQ on android. But TQ PRO paid version does show cam timing it says. Here is a list in this HTTP
http://interfusecorp.com/2011/07/elm327-obd-ii-software-guide/
Few other links
http://www.scantool.net/obdwiz/
http://www.tradevv.com/chinasupplie...USB-Ecu-Chip-Tuning-Ecu-Reader-And-Write.html
I bought the Elm327 Bluetooth Dongle
I have a bluetooth dongle on my Laptop so I can use it for PC/Linux based software or on my HTC Amaze.
There is one program specifically for GMs I cant wait to try call GM Mode22 Scan Tool

Here is the PAID ver of Torque
https://rapidshare.com/#!download|843p12|1122865944|org.prowl.torque.v1.4.65.apk|2418

The apps name is Torque,
The Hardware to look for is ELM327.
The software is opensorce and forever upgrading . There is Software for GMs specific ( GM Mode22 Scan Tool) I just bought the chip for 15$. Theres so many apps and software.

https://play.google.com/store/apps/...?t=W251bGwsMSwxLDEsIm9yZy5wcm93bC50b3JxdWUiXQ..
https://play.google.com/store/apps/...51bGwsMSwxLDEsIm9yZy5wcm93bC50b3JxdWVzY2FuIl0.
https://play.google.com/store/apps/...9tLnBhbG1lcnBlcmZvcm1hbmNlLkRhc2hDb21tYW5kIl0.
https://lh3.ggpht.com/Gire3RWpiQd1IH1FybYrWTKV6l_aE9KnIQgbUJwCVbaajq8t1lI6MUuYXwByFJxnfUac
https://lh4.ggpht.com/1aBrlcJJYB71t5ntgIdI2-N-nAIjDju2SRmx6iC08TKgT_d42fO57F2BJL8PTnUbmgf0
 
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3linkedchevy

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This was an awesome write up, another member shared it with me when I was having trouble getting the truck started after pulling the distributor. Saved me ALOT of wasted time. Thanks for this
 

Bricksack

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How would the truck run if the distributor is not set correctly. Say a little off or it was set on the exhaust side not compression?.

Sent from my SCH-I605 using Tapatalk 2
 

Aloicious

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that would depend, if its just a little off, and you're not getting the DTC code, then the computer can compensate a little for the error. but its definitely not ideal. its not like an oldschool distributor where clocking the distributor will actually change the timing (exhaust/intake etc..). the distributor position in these is really only for the PCM to correlate the crank and cam positions, then the PCM will fully control the spark for whatever conditions you're running in.

If you're not able to get ahold of a scanner that can read it, I'd cruise to the dealer and have them set it, shouldn't take more than a few mins, but they'll probably charge an hours labor for it.

@3linkedchevy - thanks, glad it helped out.
 
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