Mmelmann

iTrader: (1)

I can't explain it. It seems like it defies logic.

I installed a 3" Helix V2 downpipe, a Perrin 3" cat back, and then sent my ecu to Shiv with the instructions that I need a map for 93 octane and a full 3" turbo back exhaust for my Evo 9. (I actually didn't have the "full" exhaust yet... i.e. didn't have the cat delete yet) So, I got the reflased Vishnu Ecutek back in the mail... plugged it in and boy, what a difference. I loved the power bump, very good turbo hit.

Well, the thought of running my car with the stock 2.5" cat in place bugged me, especially since the ecu was tuned otherwise. I felt like it was a cork in the system. So, I bought the Ultimate Racing 3" test pipe and installed it expecting to experience the full potential of the ecu... i.e. like an extra 12-15 hp increase with a catless system vs the stock cat. After the install, I felt like the power wasn't exactly there. If anything it almost felt less powerful. It was a smoother power delivery with a louder note but, it just doesn't feel like I'm pushing more power or perhaps it feels like I lost some of the torque that I had before when the cat was in place.

What's going on? Anybody else felt this before? Am I going crazy? Hey, where are my pants?

GPTourer

Not possible. Maybe the ECU will adjust some pramaters to gain more from adding the test pipe, but there's no way you lost power going to a test pipe.

Mmelmann

iTrader: (1)

With my suby, I can pull the power to the car and that will cause the ecu in that car to "reset". After doing so, I use a process where you go back out to the road, get up to 3rd gear without getting into any boost, get up to 2,500 rpm, apply a load to the car by applying brake pressure while simultaneously increasing throttle so that you can get up to around 7psi at 2,500rpm.

What this does (from my understanding) is to help accelerate the "learning" process of the ecu's knock position sensors or whatever. It basically brings the ecu right up to it's most powerful threshold, like it's left or forgotten how conservative it was because of learning.

I'm going back over to nasioc to remember how to explain this one. Sorry for the confusion and for being a traitor. (I hate nasioc by the way)

GPTourer

That has been a controversy with DSMs for a while, but I think most agree to NOT reset the ECU, and just let it learn the fuel trims on its own. It will take 3-4 days of regular driving.

Tureno-AE86

maybe you have a bit more back pressure so the car's respond time is slower but more juice when the power comes on

Mmelmann

iTrader: (1)

Here is Shiv's quote from over there.

Just a little trick that has been shown to accelerate the factory ECU's ignition timing learning process.

Background: There is something called "Ignition Advance Multiplier". It represents, by some complicated algorithm, the average learned positive knock correction applied to the ignition maps. It's represented in 1/8th degrees increments. 1 being the lowest and 16 being the highest (1/8 to 2 degrees in absolute terms).

The "happier" (knock free) the car is, the higher the number will be. Conversely, the lower it is, the more knock prone it is. This number, after ECU reset ore ECU swap defaults to 8 and usually creeps up to 16 (if well mapped) through normal driving. Depending on driving characteristics, this can happen within a few hours or a few weeks. Well, here's a way to make it happen in about 5 seconds ....

First: With the car fully warmed up, reset the ECU. This can be done by killing power the ECU or by simply pulling off the neg. battery terminal and pressing the brake pedal for a couple of seconds.

Second: Drive to a nice open road without traffic. Don't go on boost until you get there. Put the car into gear (3rd gear works the best) bring the revs up to 2600rpm. Push the go pedal down slightly so boost stays right around 2-4psi. You will need to MAINTAIN 2500rpm and 2-5psi for approx 5 seconds. You can do this by left-foot braking gently as to prevent acceleration. During these few seconds, the advance multiplier (which you can't see so you'll have to trust me) will go from 8, to 12 and then to 16. Works like a charm. And on our reflashed ECU, is worth an immediate 10-20 horsepower

In an attempt to save a lot of dyno time between reflashes (when the advance multiplier resets itself), I do this little trick after every reflash. In a typical dyno session, it's not unusual to reflash the same car up to 5 times. On the dyno, all I need to do is tell the dyno to hold revs to 2600rpm. Then I just lay on the throttle until I see a few psi of boost... Bingo!

Warning: This little trick artificially speeds up the learning process. This is only a good thing if the re-mapped ECU is mapped properly. If there are trouble-spots where knock is present, this trick will make it even more present. So be careful!

Cheers,
shiv
www.vishnutuning.com

Mmelmann

iTrader: (1)

That sounds in line with what I was thinking too. I guess that's it.


So, with the reset idea... bad idea on an Evo 8 or 9?