On 2001-08-14 11:21, Z06 Tom spewed forth this drivel:
John,
I'm looking to maximize my performance based on my modifications. I have had several forum members tell me I need to have ECM programming done to get the results I want from my mods. (See "Back From The Dyno" on "Pit Road") I was wondering, in order to do the ECM work, do you need to have the car? It sounds like you did very specific work on the car you referenced. Can the programming be done with just the ECM in hand. (San Jose is a long way from Columbus, Ohio) Any advise would be helpful. (Please speak english) /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_biggrin.gif
Thanks!
Z06 TOM,
You mention an ECM which is for C4 Corvettes. I assume you mean the PCM which is used for C5s.
You have three paths you can take.
1. Send your PCM to some vendor who uploads into the flash memory changes to certain tables ( like fuel trims), change value on certain functions ( like timing, when fans come on, etc). The problem with this is of course every time you need some type of PCm change you have to yank the PCM out and wait for the unit to be shipped back to you.
2. Buy a product that gives you a little hardware unit that you plug into the PCM and upload the modified code into the flash memory. The problem with this is you still do not have full control to change what you want and what values you want. Most products like this allow minor changes like at what temp fans turn on but do not allow you to change the important functons like timing, fuel tables, etc.
3. The PCM monitors functions like the MAF, IAT, knock sensors, cam sensor, etc and decides on what they tell the PCM for it to dicate how the car will perform.
Knowing that this path instead of being dependent on some vendors product working within the PCM, is to control the PCM from the outside by changing the values the external functions are reporting to the PCM.
In looking at your mods, I would say if anything that your fuel trims may be running in a lean state ( because of the increased incoming airflow and with headers allowing better end to end flow allowing more air to be consumed. I also would not be surprised that your timing is a bit low and and WOT not being tuned for best performance.
Now you can go to those vendors that sell you so called custom code, but you have zero ideas what they really did, or even if what they sell you is a good overall tuning or could in fact give you very little performance and from then on you are dependent to that vendor and his costs.
In choosing the path I took, I found that so called custom PCM coding ( in this case is powerloader brand) that was in my '99 C5 was not giving the engine the best tuning configuration and in fact fuel trims were way too lean and and WOT too rich.
Wanting full control of functions like air, fuel, timing, knock, and WOT I choose to use a MAF translator which is a simple electronic circuit that takes 5 minutes to install.
I connects inbetween the MAF and the PCM and has to rotary switches which anyone can understand how to use.
It allows me to dictate/control ( by fooling the PCM ) what those functions are set to being the translator (MAFT) is adding or subtracting to what the MAF is reporting to the PCM.
In simple terms, by monitoring the PCM with decent PCM scanner tools ( I find the Ease enhanced powertain to be the best scanner) you can know exactly how your engine is performing, what functions need to be tuned and you simply twist a rotary switch to dial in the correction you need to better then overall performance.
Some people who have bought PCM custom code found no real performance at all, some find a bit better performance, and some think good performance, but without monitoring the PCM, they are really in the blind as to what really is going on and jsut becaise they are not getting and error codes they think everything is just find when in fact as an example the PCM does not even report a fuel trim problem untill the fiel trim is 25 percent off of being perfect.
Thus your engine could be running 24% too lean and you would not know it.
I myself do not do custom PCM re-programing, I found it much easier, quicker and in the long run far cheaper to re-tune for best performance with just the MAFT and the Ease PCM scanner.
I've worked on about 12 C5s ( most via the internet) and in using the MAFT and scanner have corrected issues such as knock, low timing, too rich/lean fuel trims, high intake air temps and O2s also not seeing the best A/F ratio for performance.
My 1st chassie dyno before tuning was like 380 RWHP with only about 360 ft/lbs.
With proper changes to intake airflow, its temp, and fuel ratio the latest dyno after tuning with a MAFT is 407 HP at 400 ft/lbs of torque. All was adjusted out, timing went from 22 to 28 degrees while in WOT and fuel trims are close to zero which is perfect.
Costs for a MAFT is only $175 and I also can obtain for you the Ease PCM scanner for about $300 which can be used for all you monitoring of engine needs.
If you decide to go with custom PCM code, be sure the vendor allows you to save your stock code and you having a way to reload it back into your PCM esp if your C5 is in warranty and go have to go to a dealer for warranty work.
Also question what functions they are tuning and demand to know the values they are changing those functions too.
My suggestion if you go with that route is go to Ron Zimmer of Z-Industries, he has been doing custom code for Corvettes since 1994 and I have used him in the past for my C4s and know he does quality work and is not guessing on how to properly re-calibrate your PCM for top performance.
John
