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Old 10-12-2012, 08:38 AM   #3
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Join Date: Oct 2012
Posts: 780

One last non-tuning issue you might deal with is the A/C. some of you may not have this problem, but mine is an early ’96 truck and the PCM setup did not work with my A/C. it ended up being easy to fix though. What I had to do was this: I eliminated both the high pressure and low pressure switches (just unplugged them, and spliced both wires together from the connector on each sensor), then you need to install an LS1 3 wire A/C pressure sensor on the Schrader port coming off the high pressure line, this is wired with connector pin A (or 1) going to PCM pin C2-57, connector pin B(or 2) going to PCM pin C1-45, and connector pin C(or3) going to PCM pin C2-14. And lastly, you’ll need to splice in an extra wire off the dk green wire going to the A/C compressor clutch and run it back the the PCM pin C2-18. This will provide an actual A/C pressure input to the PCM, and allow the PCM to control the A/C correctly, as well as cycle e-fans and such based off A/C pressure. I could not get mine to work with the A/C switches that were in the ’96 originally. You may not have this problem, especially if you have a clutch fan or a non-PCM wired e-fan. However I find that the PCM wired E-fan is the way to go, the 411 does an excellent job with them and is extremely reliable.

Now that everything is installed, we need to work on the tune. I had some initial problems with the tune, you HAVE to use an LSx based tune for it all to work, you can’t use a Xvan based tune and copy the LS1 tables in, it won’t start. So what you need to do is start with a good LS1 tune, I used a 2002 Fbody tune, copied the tables like VE and spark maps and other pertinent tables (a lot of them, I’m not going to list them all, but it was a lot of the engine calibration section) into the Fbody tune, but left the Fbody coil tables as is (i.e. dwell time, etc) to work correctly with the new setup, I also searched out all the tables that were referenced to the 24x crank signal, and kept them the same as the Fbody tune. Its an involved process, and if someone needs help with it I can help out, but I’m not going to list the dozens of tables that do and don’t need altering. Here is the EFiconnection sites with some stock tunes as well as tunes people are using:

One thing to note when choosing a base tune to work with, the 24x setup has the ability to run a drive by wire electronic throttle, as opposed to the cable driven throttle that we use on our trucks. If you run the drive by wire, you need to use a base tune that is drive by wire (i.e. ’02 vette, ’02 esky), but if you’re going to use the cable throttle, you need to use a cable throttle base tune (‘02 Fbody, ’02 silverado)
I have not done the electronic throttle swap yet, so I’m not going to go into that, if you want to run a drive by wire TB, contact eficonnection for help.

last not I'll make about tuning is to get the tach signal reading correctly. it is just a change in tables G1204 & G1205 (I think those are the tabe #'s I'm not on my tuning computer.) its for the high and low tach pulses. stock LSx tune has them at 6, the Xvan tune has them at 1, I found that at about 3.3 the tach signal was pretty accurate throughout the RPM range.

Once you get the proper tune in the PCM, you can start ‘er up. Mine has been running flawlessly for about 8months. I no longer have the problems that I did with the cap/rotor, the idle is smoother, I’ve got boatloads more control over the coil and spark through tuning, and the setup is SO much more reliable. if you aren’t already, once you get into tuning, you can play with settings for things like spark dwell and such. Here is a nice video comparing the LS1, LS2, and gen III truck coils. It has a lot of good information about things like dwell time and can help with tuning things like that.

That’s about it, I wrote this at 4am so if I left anything out, I will add it in, if you have questions, feel free to ask. Here is the thread from when I installed this on my truck, I did A LOT of things at the same time including installing the whipple, new heads, etc, etc, so the whole thread isn’t about just the 24x and coils, but there is a lot of info in there about it.

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