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View Full Version : Is the factory PCM capable of doing what I want?



helpless
December 18th, 2013, 03:04 PM
About a year ago I purchased a 1998 WS6 with the intent of building a car that I could keep somewhat streetable yet make quite fast at the strip. During the last year I have built a new motor and started construction on the car. Through the advice of somebody who has more experience with the factory LS PCM's I purchased a 2002 PCM from a Camaro and purchased EFI Live. Let me add I do have some experience with some stand alone EFI systems but the GM systems confuse me. I originally built the engine to be a good street performer and planned to spray as much as a 400 shot of nitrous to get the 1/4 mile times I am hoping for however I don't think I will need the entire 400. Anyway I just started looking into progressive nitrous controllers, window switches and timing retard boxes and a launch controller which adds up to around $1800. Then I considered the purchase of a stand alone system from Holley, the Dominator looks to be pretty awsome and would cover all my bases except the factory dash and possibly ABS might be tricky. The auto tune was a big selling point but I see that EFI Live now has that feature. I have been told everything from the stock PCM just can't do it to it will do all of what you want and is better than a stand alone. Can I do what I want without adding a bunch of controllers that may or may not work so well together? If there is somebody who has the knowledge to do everything I need and can step me through it would be fantastic, I have no issues paying for the info as long as it's accurate and will work properly in the end. Anybody interested?

minytrker
December 18th, 2013, 04:05 PM
No factory pcm can "auto tune" and a 98 pcm has even more limits than a 99-02. In order to a run a 99-02 pcm you would have to re-pin your harness. Auto tuning is just a process of tuning off data logs and using that data to correct your fuel tables, efi live doesnt do it for you. With a stock pcm and efi live you will still need a nitrous controller and all your safeties. The custom operating system can pull timing but depending on what 2 step you buy it can most likely pull timing also. With the stock pcm you will need other add on boxes. With the holley if you purchased all the add ons you could control your whole car without the need of other modules. However holley isnt setup to run factory abs or factory clusters.
There is no "auto tuning" anything out there. You still have to get all the tables close with good data and most aftermarket setups will self adjust your a/f ratio based off a single or dual wide band sensor. Some will pull timing based on knocked sensors. Thats about all thats "self tuning". An aftermarket ecm setup may be easier to tune because it wont have hundreds of extra tables for emissions and drivabilty like the stock pcm has.

helpless
December 18th, 2013, 04:22 PM
Thanks for your response and being honest. I was aware of the "self tune" as you stated I was just getting at it saves alot of time. I was set on the Holley a few days ago but today talked to a few people that seem to think I can do most of this with the stock ecm, by the way I already went to the 2002 and repinned. Its a shame the the drivability suffers on stand alone. I do hope to pass emissions but have some alternatives if I can't. In the end I can't honestly say if I care more about streetability or racing. I do know that a that runs good only at the track is no fun except at the track. Tell me minytrker what would you do? Stock with add on boxes or stand alone?

minytrker
December 18th, 2013, 06:32 PM
I have been running stock pcm for years in my camaro making over a 1,000hp at the wheels. I tune more 1,000+hp cars on stock pcm than after market. I am only switching to an aftermarket setup because Im going bigger and straight alcohol. Im a fan of stock pcm but I also been tuning almost 10 years so its not a big deal to me. Dont get me the aftermarket setups are nice and have everything built in them but most of the cars I mess with that are big hp slowly got there so for them its not worth the money to switch. You can have great driveability with any system, just depends on how much time you want to spend tuning it.

MikeOD
December 29th, 2013, 03:50 AM
My opinion (also been tuning for 12 or 13 years now) is to stick with the 2002 PCM and use the EFILive enhancements if applicable. There are also a LOT of other tricks for doing what you want with nitrous using the stock PCM...I think all you'd really NEED to add is a window switch to actually turn it on/off when you want...or whatever on/off you need for a multi-stage shot.

I generally (not always and I hope this doesn't offend anybody) find that there are 3 types of car guys...those that swear by carbs, and those that swear by EFI...the third type is those that USED to swear by carbs, and have made the switch, but don't understand how a stock computer could be any good, and thus swear by aftermarket EFI.

I think they all have their place (carbs, afterarket EFI and OEM EFI)...but to be honest, anything with a GM controller since the introduction of the LS1, I don't think I could justify a swap to aftermarket unless I was making 1500+ hp. I could absolutely justify going to a 99+ LS1 PCM in a 97-98 car, which you've done, but that's really about it. Heck I even have a hard time pulling an LT1 away from the 8051 PCM...but removing an optispark is always nice.

joecar
December 30th, 2013, 12:04 AM
The advantages of OEM PCM are:
- various protection modes,
- very detailed sensor failure detection (DTC's),
- cheap replacement in case of failure,
- ability to control GM 4-speed automatic transmission (4L60E/4L80E),
- ability to provide excellent driveability,
- ability to pass emissions testing (by virtue of providing the necessary OBD-II reporting).


What minytrker said above, and from my reading, even with aftermarket systems which use a wideband, you still have to perform tuning to arrive at the correct airmass model in order to zero the wideband correction (besides avoiding pegging the correction, you want to zero the correction in case the wideband fails and is unable to provide correction).

MikeOD states an interesting categorization of car guys :cheers:

picnic_george
December 30th, 2013, 04:50 AM
Sounds like what you're looking for is a stand alone. The stock PCM just can't do all that to my knowledge. COS can retard timing that's about it. Since you already have EFIlive, get an NOS launcher it has a controller and window switch in it and run an msd 2 step, you're closer to $600 than $1800. Unless you're including the purchase price of EFIlive.
http://www.summitracing.com/parts/nos-15977nos/overview/

http://www.summitracing.com/parts/msd-8733/overview/