oldred95

First of all the info I'm after is probably on here somewhere but doing a search I get so many thread hits and dead ends if its there I can't easily find it. 99s seem to be kind of special, 270 horse, small cam, small injectors, different PCM. I am working on getting it tuned and I would like to incorporate everything I can while I'm at it. I would like to put a factory efan setup from a 05+ truck on it someday and control them with the PCM exactly how GM does it. Both fans in series on low, both fans in parallel on high. I was not able to find anything definitive whether or not the 99's PCM could do this. The other thing is lean cruise. I found the thread that had a link to another thread about the code patch and in the screen shot of EFI live it says for 2001+ LSx engines. Is it the PCM that is the limiting factor here or is it something else? Also I found a few threads mentioning swaps to the 02 PCM but it was nothing more then you can do it or I have done it. What all is involved in the swap? I want to say the connectors are very similar if not the same but does anything have to be repinned? From a programming stand point you just flash in the 02 program and make the changes you want like usual right? Sorry for all the novice questions. I've been playing with OBD1 stuff for several years but OBD2 is completely new to me.

Rhino79

iTrader: (7)

Reflash your 99 with the 02 operating system. Lean cruise is only really in open loop mode. You can fudge your o2 switchpoints to lean it out a little though. The knock sensor and timing modifier tables are much better in the 02 os.

oldred95

Is it really that simple? Just reflash, thats it? I know the 2002's I've driven just run so much better then the 99-00s.

Rhino79

iTrader: (7)

Thats it, youll need to copy over the calibrations form your 99, some of the cals are different, but just pluf your numbers in and youll have more tables in the 2002 and alot better table resolution

oldred95

I had no idea it was that easy. Otherwise the PCMs are physically identical? I think for the mean time I will get it tuned for 91 octane and get it shifting right and leave it until I get EFI live myself then I will seriously have to consider the 02 operating system.

oldred95

Got my hands on my tune file and I have reviewed it with the demo version of EFI live and its pretty interesting. EFI is so ridiculously pud to use its not funny. I'm used to a thousand page long notepad file with nothing but broken English, slang, and tuner jargon that has to be interrupted into tables, flags and constants to make changes and make things work. EFI live is just too easy but for the money it ought to be.

Anyway I found the efan settings and it seems as though mine is capable of controlling two fans setup in series parallel. It says type of fan setup and series parallel is selected, then it has the break down of fan 1 on and off and fan 2 on and off and AC on and off and so on. The general consensus I got from reading on here was that the 99 PCM is not capable of controlling two fans in series parallel without the 02 operating system but my tune file suggests otherwise.

Rhino79

iTrader: (7)

It should control both on the 99 system, the f-bodys from 99 used a dual fan setup, fan 1 on about 10* sooner than fan 2...The best part of the 02 over the 99 system is the better ve table tuning (lack of backup VE) if going sd, alot better spark vs iat resolution as well as spark vs ect resolution, knock sensor settings are way sensative in the 99 system and there is an addtional table added in the 02 system.

oldred95

So the 99 operating system still has two outputs for fans, 33 and 42 IIRC? I may upgrade to the 02 operating system later on down the road but for now and for the last 11 years for that matter, its been working fine as is.

Rhino79

iTrader: (7)

You should be fine with the 99, you can even download an 02 file and change your knock settings in the 99 to match the 02, false knock was a problem on some of the older os's

jlwz71

iTrader: (3)

I put the 02 system on my 99 pcm with no problems. I then modded the 02 OS to suit my needs. Been that way for a few years now.