Thanks Gurgen,

In my case the installer will be the tuner, so the pre-tune drive will be a PITA, but if it's necessary then I'll do it for sure.

Ok, so let's see if I've got this. (hypothetical situation described below)

step #1: Get the S/C installed on Tuesday.
step #2: Go drive the car but don't go past ~3000 rpms for say 20-100 miles that evening after the install.
step #3: Go back for a tuning session on Wednesday.
step #4: Drive and have fun from Wednesday afternoon on.

Questions:

1. The thing that I find confusing is that if I don't really 'get on it' or if I don't hit boost during my pre-tune drive on Tuesday night, how is my car relearning what it needs as far as A/F and fuel maps are concerned?

2. Isn't it true that the 'more aggressive' fuel map(s) will not even be seen during this less than spirited drive?

3. Also, isn't there a default WOT fuel map? Doesn't the car simply default to this fuel map under WOT and not read data from the O2 sensors, so that dyno tuning at WOT would never change regardless of the number of miles traveled?

Since I have an intake (which will be gone with the addition blower), plenum, headers, h/f cats and exhaust I'll should be much more lean after adding the Vortech than someone who installs the system on a stock engine. This is my big concern about a pre-tune drive that doesn't see boost.

 

PRetty much...

THe biggest portion of learning takes place within the first few minutes. That's where the injecotr table is referenced to put in X amount of fuel for Y amount of ait. Well, when you have bigger injectors and/or different fuel pressure, the programmed injector duration now equal to more fuel than originally intended. The 02 feedbakc is sensed (short term fuel trim), and the injector duration is decreased.. to get you back to 14.7:1. After a little while, the ecu sees that this is happening the entire time, and adjusts the long term fuel trim value, which is then subtracted from ANY type of injector duration spit out by the ecu, including WOT. THis is why, basic leaning shoudl take place before you tune. However, most of the time this is not an issue, since close to 80% of the lt trim will already have been determined simply during the drive to your tuner (takes 10-15 minutes or so).

True, hence take it easy and don't go over a couple of psi of boost and 50% throttle. THe thing is that whe nyo ucar runs in closed loop mode, all the other mods do not matter. The 02 feedback is taken into account to always keep your mixture at 14.7:1 (lambda=1). In open loop mode, the ecu kind of takes a leap of faith, and jsut adds predefined amount of fuel for the air measured. this is where it can be dangerous, and requires a tune.

 

Thanks for the clarification (darnit I need a cool/respectful nick name to refer to you by) Gurgen. I didn't understand the injector duration and fuel trim relationship specifically concerning WOT well enough, but now it's much more clear. It sounds like a good 50+ miles of granny driving will be in order before the initial tune at a minimum.

CP Racing said that they've never had to re-tune a car the next day and they usually send people out for a conservative drive before their tune. I think I'll just drive 30 or so minutes through in town traffic one way and then turn around and head back to the shop before the tune. I'll keep her around 3000 rpm's (or really under 2psi) the whole way and this should be easy for me to do after all of this anticipation/waiting... yeah right.

Thanks again.