Case study number 9 - AEM tuning
Thread Starter
Account Disabled
iTrader: (91)
Joined: Sep 2003
Posts: 16,850
Likes: 0
From: 2003 Evo VIII - Silver
Case study number 9 - AEM tuning
Today I was pleased to have a most intersting day tuning a AEM equiped evo
Mods were
AEM Speed desnity
3" exhuast
264 cams
Injen air intake and pipes
Denso 660 injectors
Walbro fuel pump
The owner had been to another AEM tuner several times with complaints of hesitation and bad driveability. Apparently he had a decent number on the dyno but little time was spent on road testing and driveability.
To me - it seems a trend in tuning for fast, slam, bam tuning with a focus on high dyno numbers and little attention paid on real street driving and the driveability and "feel" of the car on the road.
I started off hooking up all my gear on the car and going off for a long 60 mile trip.
Right away I noticed that the car felt very jerky and unsmooth in the throttle response.
I started to try and get to the bottom of the situation and discovered that the LOAD reference on the fuel map was set to TPS based ! Even though the ecu had the map sesnor and was set up for boost comp tuning. It took me a few minutes and searchng to find the way to turn off TPS based fuel map in the options menu. Thereafter, I was off to start a totaly new fuel map based upon MAP or pressure based LOAD. Thankfully, I soon realized that this was the #1 problem with this customer's car on the driveability and now it would just take some tuning to dial in the power and smoothness factor that I strive for.
First step in tuning the AEM is to dial in the VE of the engine with the fuel graph to create a smooth a/f ratio across the board. ON AEM tuning I look for a 11.3 / 1 a/f ratio across the board - possibly getting a tad richer if certain areas are having knock.\
After dialing in the a/f I turn next to ignition triming and carefully adjust the timing with the knock controll turned OFF to look for knock activity. I try to dial in the ignition timing right below the threshold where kock activity begins. On 93 octane like in this car the timing winds up quite conseravtive.
I was alarmed to see the oginial timing figures compared to the final ones I set. One of the reasons I like to tune on the road is that it gives us a real life load reference which can bring out knock activity much better than dyno pulls. After about 3 hours of doing pulls, loggng data - reviewing logs and making corrections I had the car running totally knock free - smooth as stock and very strong.
There is no doubt that my conseravtive manner of tuning creates a weaker car with slightly less power than one tuned with aggressive timing and super lean a/f. However, you wont find any knock activity at all on cars which I tune. I think ist more important to maintain total reliability and err on the side of caution in tuning.
Next up was dialing in the right a/f's on cruise to help the car get decent gas mieage. This involves driving at highway speeds watching the wideband.
Next we tackel the accelertion and deceleration enrichments to ensure that they are adjusted for the particular car.
Finally - the car is stopped and allowed to cool off for a couple of hours to be able to re-adjust the cold start.
In the end - this tune took about 6 hours of time. My AEM tunes are not rush jobs.
The end result produced a car which ran almost as smooth as a stock ecu and which was making some decent power on the dyno.
Mods were
AEM Speed desnity
3" exhuast
264 cams
Injen air intake and pipes
Denso 660 injectors
Walbro fuel pump
The owner had been to another AEM tuner several times with complaints of hesitation and bad driveability. Apparently he had a decent number on the dyno but little time was spent on road testing and driveability.
To me - it seems a trend in tuning for fast, slam, bam tuning with a focus on high dyno numbers and little attention paid on real street driving and the driveability and "feel" of the car on the road.
I started off hooking up all my gear on the car and going off for a long 60 mile trip.
Right away I noticed that the car felt very jerky and unsmooth in the throttle response.
I started to try and get to the bottom of the situation and discovered that the LOAD reference on the fuel map was set to TPS based ! Even though the ecu had the map sesnor and was set up for boost comp tuning. It took me a few minutes and searchng to find the way to turn off TPS based fuel map in the options menu. Thereafter, I was off to start a totaly new fuel map based upon MAP or pressure based LOAD. Thankfully, I soon realized that this was the #1 problem with this customer's car on the driveability and now it would just take some tuning to dial in the power and smoothness factor that I strive for.
First step in tuning the AEM is to dial in the VE of the engine with the fuel graph to create a smooth a/f ratio across the board. ON AEM tuning I look for a 11.3 / 1 a/f ratio across the board - possibly getting a tad richer if certain areas are having knock.\
After dialing in the a/f I turn next to ignition triming and carefully adjust the timing with the knock controll turned OFF to look for knock activity. I try to dial in the ignition timing right below the threshold where kock activity begins. On 93 octane like in this car the timing winds up quite conseravtive.
I was alarmed to see the oginial timing figures compared to the final ones I set. One of the reasons I like to tune on the road is that it gives us a real life load reference which can bring out knock activity much better than dyno pulls. After about 3 hours of doing pulls, loggng data - reviewing logs and making corrections I had the car running totally knock free - smooth as stock and very strong.
There is no doubt that my conseravtive manner of tuning creates a weaker car with slightly less power than one tuned with aggressive timing and super lean a/f. However, you wont find any knock activity at all on cars which I tune. I think ist more important to maintain total reliability and err on the side of caution in tuning.
Next up was dialing in the right a/f's on cruise to help the car get decent gas mieage. This involves driving at highway speeds watching the wideband.
Next we tackel the accelertion and deceleration enrichments to ensure that they are adjusted for the particular car.
Finally - the car is stopped and allowed to cool off for a couple of hours to be able to re-adjust the cold start.
In the end - this tune took about 6 hours of time. My AEM tunes are not rush jobs.
The end result produced a car which ran almost as smooth as a stock ecu and which was making some decent power on the dyno.
