I Read a few thread around here where it was mentioned that an Evo 9 needs to be tuned to take advantage of the TBE and other intake mods. The argument was that the ECU adjusts and negates the gains from the higher ariflow, hence the need for a tune.

I alwyas wanted to test this. A friend of mine bought an Evo 9 SE and we logged it stock with a test pipe (so I can get AFR readings) and ran the numbers into Dataloglab to get the power readings. That happened back in October 2006. Since then the owner did the following mods:

1. 3" TBE with test pipe
2. Nesei LICP
3. K&N drop-in
4. Airbox silicone hose
5. No MBC and the boost was not logged.

These changes were done over time and the car was driven for a long time allowing the ECU to adjust. Yesterday he came by and we logged the car again. We placed the wideband in the same place and went to the same stretch of road to keep the road profile constant.

The car produced really good power gains. Below is the before and after chart. It is SAE corrected to allow comparison and keep environmental factors constant. Do not look at the peak numbers, but the improvement and the area under the curve. This car is not tuned yet and it is putting good numbers. The ECU did not adjust and kill the party as some have said the 9s do. But this is only one sample, to be sure.



Another thing that I noticed is that the AFR leaned out on the car after the mods. Here is the before AFR of the 3-4 runs that we made back in October.



Here is the AFR of the logs we did yesterday. Notice how the AFR dips below 11:1 @ 6000 rpm whereas before it dipped below 11:1 @ 5000 rpm.



The car, however, did register a consistent 6 counts of knock @ 6500 rpm. Given the very good AFR below 6000 rpm, I would only tune the car above that rpm. I would lean out the mixture to 11:1 and pull timing up top, assuming that the boost is kept at stock level. Given that the car is running CA 91 octane gas, then IMO keeping the boost @ stock levels is a really good idea. Just use an MBC to hold the boost better.

 

I did back to back pulls (on the same day) of an evo IX before and after a 3" catback. Same deal ~20hp and about the same torque across the board.

How are you charting your AFR map? I'd like to see if I can go back and look at mine.

 

I think the gains on the stock boost control system will depend on whether the car can reach target load or not. If it can't and you improve the breathing you'll get more of a gain than if it was already achieving target load.

 

One on the reasons we waited so long between the tests was to allow for the ECU to adjust. The theory was that if you tests back-to-back, then you will get gains, but after that the ECU will adjust and negate the gains. Well the ECU had plenty of time to adjust and the power was not negated.

The AFR mapping was doen with Logworks. I can create one chart that will include multiple runs. This way I can get a good average of the AFR.

 

I've not found any learning that would be needed like a Subaru. Only the octane value really.

 

In the stock run the LoadCalc was 240 @ peak boost/torque and in the most recent run the LoadCalc was 242. There was little difference in the load target between the two runs.

 

The stock evo ecu does not "learn" in open loop. It only "learns" by adjusting fuel trims in closed loop.

It however can pull timing based on knock and octane level. It can also change boost depending on changing loads (like more airflow from exhaust mods, etc)

The big big gains from evo 9's are tuning the Ignition timing and mivec. It runs very very little from the factory down low. This is why most 9's with turbobacks and stock tunes run way higher HP than TQ.

Add a couple degrees of ign timing at peak torque and around and walla! Instant 40+wtq.

Here is a good example of this, it is also using stock boost control, baseline is stock ECU and test run is after tune. All mods the same before/after.



Good findings however NJ. I also haven't seen the "kill the party" problem on 9's with mods and no tune. However, the peak trq AFR can be a little lean for my comfort on 91 octane fuel with a little more boost. So that is a good thing to get changed with a tune.