PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Multiple tunes on one PCM?

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Old Apr 29, 2009 | 01:33 PM
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Default Multiple tunes on one PCM?

I may just be completely wrong on this but I thought I read somewhere that some of the tuning softwares will allow more that one tune on a single pcm with the second tune being activated by a switch of some sort. Is this right or am I just making stuff up? I would like to have a tune for my small nitrous kit and then a seperate tune for the big kit. I don't care about having a NA tune I just don't want to be daily driving on a tune with very little timing because of the bigger kit.

Any help is greatly appreciated.
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Old Apr 29, 2009 | 01:39 PM
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I think you need 2 PCMs. Just change them back and forth when you need them.

Last edited by TedsB4Csled; Apr 29, 2009 at 01:49 PM.
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Old Apr 29, 2009 | 04:57 PM
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Originally Posted by DopeFedZ
I may just be completely wrong on this but I thought I read somewhere that some of the tuning softwares will allow more that one tune on a single pcm with the second tune being activated by a switch of some sort.
my pcm had a alternative tune for n2o, i never did use it, but if i understood it correctly, their is an unused wire on the pcm plug that can be hooked to the ground of the nitrous relay, when the relay is activated the pcm sees the ground signal and puts it on the other tune......... im certainly not a tuner, and i dont know which wire, but their is a way of doing it, and not by changing ecu's
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Old Apr 29, 2009 | 05:07 PM
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Originally Posted by sprayinLS1s
my pcm had a alternative tune for n2o, i never did use it, but if i understood it correctly, their is an unused wire on the pcm plug that can be hooked to the ground of the nitrous relay, when the relay is activated the pcm sees the ground signal and puts it on the other tune......... im certainly not a tuner, and i dont know which wire, but their is a way of doing it, and not by changing ecu's
Thanks man that sounds like what I had heard before or seen somewhere but I just can't remember where .

Anyone else?
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Old Apr 30, 2009 | 07:43 AM
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there is a company in australia that has what your looking for, with 2 or 3 44pin flash chips in the pmc but for the cost you could get a custom tuned handheld and just swap tunes much easier.

http://www.ls1.com.au/forum/showthre...witchable+tune

Ryan
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Old Apr 30, 2009 | 10:31 AM
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Originally Posted by TedsB4Csled
I think you need 2 PCMs. Just change them back and forth when you need them.
it would be alot easier to just upload a nitrous tune when you need it rather than switching pcms...only works ofcourse if you have the tuning software yourself.
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Old Apr 30, 2009 | 10:59 AM
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Originally Posted by DopeFedZ
I may just be completely wrong on this but I thought I read somewhere that some of the tuning softwares will allow more that one tune on a single pcm with the second tune being activated by a switch of some sort. Is this right or am I just making stuff up? I would like to have a tune for my small nitrous kit and then a seperate tune for the big kit. I don't care about having a NA tune I just don't want to be daily driving on a tune with very little timing because of the bigger kit.

Any help is greatly appreciated.
Some rig up a switch with there IAT sensor, causing it to read different than actual temps which allows for timing changes.

It won't affect daily driving as you only have to change WOT timing.
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Old Apr 30, 2009 | 01:39 PM
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Originally Posted by JonCR96Z
Some rig up a switch with there IAT sensor, causing it to read different than actual temps which allows for timing changes.

It won't affect daily driving as you only have to change WOT timing.
I think I've seen that before but I'm pretty sure that only pulls 2-3 degrees of timing and that's not going to cut it for what I wanna spray.
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Old Apr 30, 2009 | 01:43 PM
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Using the IAT spark adder tables you can remove as much as 25 or add as much as 55.
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Old Apr 30, 2009 | 02:26 PM
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Originally Posted by DopeFedZ
I may just be completely wrong on this but I thought I read somewhere that some of the tuning softwares will allow more that one tune on a single pcm with the second tune being activated by a switch of some sort. Is this right or am I just making stuff up? I would like to have a tune for my small nitrous kit and then a seperate tune for the big kit. I don't care about having a NA tune I just don't want to be daily driving on a tune with very little timing because of the bigger kit.

Any help is greatly appreciated.

Its done with EFI Live COS#5 (custom operating system #5) which is free. I have had it on several cars. You can switch between NA and N2O with the car running or when ever. You can even hook it up to the N2O relays so they switch it for you. You can adjust in the tune how much timing the switch pulls or adds and when it does it.
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Old Apr 30, 2009 | 02:59 PM
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Originally Posted by minytrker
Its done with EFI Live COS#5 (custom operating system #5) which is free. I have had it on several cars. You can switch between NA and N2O with the car running or when ever. You can even hook it up to the N2O relays so they switch it for you. You can adjust in the tune how much timing the switch pulls or adds and when it does it.
COS5 is only available if you have a 99+ PCM
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Old May 1, 2009 | 08:10 AM
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I use the IAT trick for when I have the bottle running.

Just set your IAT table to however much timing you want to pull for the IAT that you have your switch/resistor set for.
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Old May 1, 2009 | 03:15 PM
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i wont claim to have any knowledge of the pcm, cause i dont haha, but just a shot in the dark, change your high octane and low octane tables to suit your needs for small shot and big shot? im guessing they switch because of the knock sensors so maybe someone could figure out how to change these manually or have the actual nitrous trip the change...

and if all this is ridiculous just disregard my rant, its just an idea anyway haha
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Old May 1, 2009 | 03:40 PM
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You can load a performance and normal trans tune with an automatic trans and switch it on and off with a momentary contact switch to ground on pin 71 of the blue computer harness, but I think it will only change transmission variables, I do not believe it will do anything to timing, fueling, etc.

D
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Old May 1, 2009 | 03:53 PM
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Originally Posted by marors1
You can load a performance and normal trans tune with an automatic trans and switch it on and off with a momentary contact switch to ground on pin 71 of the blue computer harness, but I think it will only change transmission variables, I do not believe it will do anything to timing, fueling, etc.

D
You can change TM values in your scenario but that would only effect shifts.
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Old May 1, 2009 | 08:27 PM
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Originally Posted by jmill96Z
COS5 is only available if you have a 99+ PCM
Some people have replaced their 98 PCM with a 0411 PCM, repinned their PCM connectors, loaded either the 2002 F-car file (OS 12212156) or COS5, and swapped the fuel segment in either file... it's not a big deal.

And in doing so, were able to run their 1998 F-car on either of 12212156 (single VE table) or COS5 (same as 12212156 with boost and nitrous tables added).
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Old May 10, 2009 | 11:36 PM
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Default Dual flash Units

A couple of mates and I are in the testing stage of just said units.. It is basically a LS1 PCM with 2 Flash chips loaded inside with a tune each. You can switch to either tune by the flick of a switch. It can be more used for more than just NO2.

can run either low octane or high octane fuels? hi or low settings for turbo boost etc.....

it basically allows you to have 2 full tunes in your PCM at once....

perfect idea for those that dont have the tuning software, or for those with no computer skills or to lazy to swap/upload the tunes all the time.

once we have done a bit more testing we will be able to offer these to the public.

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Old May 10, 2009 | 11:55 PM
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Isn't that exactly what they've already been doing in Oz? I just looked at that link above and it's already been done.
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Old May 11, 2009 | 12:07 AM
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yes it is.... bit of healthy competition never went astray.....


but this way (with dual flash chips) is better than the custom OS way.... guess just trying to clear that up.
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Old May 11, 2009 | 12:29 AM
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I wouldnt trust one of those IAT timing boxes. I feel much safer just swapping tunes on the laptop
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