H3 PCM Question

[jphh20]

I recently upgraded from my stock tire 285's to 315's and planning on doing the PCMforless to adjust shift point etc. My question is that I will swap wheels/tires in frequently and is it possible to have 2 pcms one for 285s and one for 315s without creating other problems? Is this a bad idea? I have seen pcms on eBay for around 100 that I could send out and upgrade but I wanted to check first on if this is even a good idea or a bad one.

Thanks

 

[f5moab]

Yes, you can have multiple PCMs for a vehicle. Make sure the part number on those ebay deals are the same, and make sure both are programmed for your vehicle.

 

[alrock]

If you're only doing it to correct the speedo, that's a lot of work for nominal gain. If you're doing two different sets of instructions, that's a different story. Either way, the connectors for the PCM scare me as those are the types of pins that users bend and break due to impatient installations. That's one reason you see computers with USB style connections now, vs. the old serial and parallel cables with their numerous thin pins.

 

[jphh20]

Thanks for the responses, I didn't think of the durability of the connectors. I think I will send mine out for the upgrades to 35' tires and have the shift points upgraded to match. If I switch the tires to my stock 33s I can re-assess if I need to make any changes.

 

[chaos254]

The pcm upgrade is definitely worth it. Just had pcm of nc do my pcm/tcm and it made a huge difference. Truck feels much better.

Sent from my SCH-I545 using Tapatalk 2

 

[f5moab]

I'm going to disagree with Alrock. If you pull the release on the connector, it backs its way away from the PCM, and to install, just position and pull the release up and lock into place. I had tech working with me in TN that removed those connectors, literally hundreds of times, and no damage was ever done.

 

[rascole]

Just my thoughts. Call PCM of NC first and get their input first. They of all will have the best answer. BUT...I just went to 315's from 285's and noticed very little change in power loss or shifting, I am already easy on the go pedal since this is not the Trailblazer SS we are driving. Worst case I would suggest a tuning for a tire size in between a 285 and a 315, not even a 1" change in tire diameter if you go in the middle.

 

[Steve #1]

I was thinking the same as rascole. There isn't that much difference between the two sizes. If you are planning on running 285s most of the time and just tossing 315s on a few weekends a year, just get a program for 285s. If your thinking summer/winter, have them write a program that is somewhere in the middle.

 

[marshall@pcmofnc]

I'd venture to say that I have connected to just as many PCMs as anyone in the world, and I have never had a problem with the pins.

 

[08H3]

7%. Just remember there is a 7 percent difference in your speed between the two tires. I swap tires as well, and there is no way I would ever consider the hassle of switching PCM just for that minor issue. On the pins, I agree with F5. The way the connector is designed, I don't see any possible way you could break a pin.

 

[4speedfunk]

True its only 7% but, there's more to the story than that. Adjusting your speedo is nothing....but the shift points for your AT and timing tweeks to the motor make 35" almost tolerable. PCM of NC has done mine twice...very happy with the results. My truck is HIGHLY modified and it runs great. I run 37"s and 5.13 gearing and it drives just like it did (or better) than the day it left the showroom.

08H3...you're a stick-shifter so you don't count! :giggle: