I recived the AEM ECU with UEGO earlier this month. I decided to take on the tuning myself. I don't mind spending the time to do it and I wanted to learn. I could probably pay someone but from my experience up to now with the AEM, there will always be things that you cannot tune properly with a simple "day at the Dyno" session other than optimizing the power output and possibly the startup issues.
One thing that I'm having trouble with are the Cold Starts and in fact the warm starts are not that good either...
The AEM is awesome. You have so much control over what happens it's scary. I'll have to say that you MUST proceed with EXTREME caution. "Don't try this at home, kids"... I've spent almost a month with over 40 driving data logging sessions and over 15 start up logging sessions and I'm still not anywhere near where I want or need to be... but I've learned so much. Making small changes and seeing the results is very satisfying.
The AEM fits perfectly in the stock location. I thought it would be too big, but it's perfect in the Accord. I have an external UEGO controller that I installed that in the engine bay. I ran the Power and Ground directly from the battery. I used the O2 heater power trigger from the stock O2 harness to trigger the UEGO power relay. I send the 5v UEGO O2 signal back through the OEM O2 harness which goes directly back to the AEM. Getting proper AFR info while driving and tuning is absolutely manditory.
I started slow and I always monitor my knock sensor voltages to ensure that I'm not doing any harm to the engine. I stayed under 2000 rpm for the first little while and slowly move up to 3000. Highway tuning, street tuning, light accel tuning, idle tuning, etc... I've gotten up to 4000 rpm now and there is excellent torque and power between 3000 and 4000. The IABs are anoying as my mechanic didn't close them fully trying to make it a "best of both worlds" static IAB setup but if your MAP (Manifold Absolute Pressure) is over 35-40 Kpa between 1500 - 3000, the IAB's make a whistling sound.
I'm now working on getting the start up perfect i.e. start like stock. Right now it cranks (grinds twice) and then catches. Proably doing some damage to my starter... I'm not sure that the startup spark / fuel inj timing is optimal. The OEM ECUs start perfectly. I've flooded the engine tuning starting and had to put an OEM ECU in to start and clear out the gas / warm up the car.
Emissions! Yes, I passed it... I tuned the AEM to pass Emissions.
My emissions was overdue and everyone who I talked to said to use one of the OEM ECUs to pass emissions. I knew that the EDM PDE (H22A7) ECU would be less likely to pass so I went with my USDM PAA (F23A1) ECU. Unfortunately the ECU throws a code if you hold a 3000 RPM which is what is required for 30-60 seconds in 2nd gear @ 40 KPH on a dyno. Once a code is thrown on a Honda ECU, you are done. It goes into limp mode and begins to dump fuel for safety and since the Idle portion of the Emissions testing in Canada follows the load test, going into limp mode under load is ok but once you come back to idle, you will fail as the AFR it too rich. The guys at the shop were cool and let me try it again and even let me clear the code right before it goes to idle, but the idle just can't burn it all in the time given.
I had the AEM but I was nowhere near being able to tune for emissions. I came back 2 weeks later after enabling my EGR and tuning my fuel maps so that all low load driving (cruising) would be 14.7 AFR. Enabling the EGR richens the entire fuel map so I had to fine tune everything to 14.7. I turned on O2 feedback and set it to maintain 14.7. I paid the shop for an hour of diagnostic time and put my car on the dyno with the exhaust sensors so we could monitor the HC, CO and NO in real time.
I had to do quite a bit of EGR tuning and re-tuning of my fuel maps and took almost the full hour to get it right. We passed with flying colors.
Load test @ 40 KPH / 3000 RPM (30 seconds min / 60 seconds max)
HC = 13 ppm (62 ppm to pass)
CO = 0.00% (0.35 % to pass)
NO = 314 ppm (467 ppm to pass)
Idle Test
HC = 11 ppm (150 ppm to pass)
CO = 0.00 % (0.70 % to pass)
NO was not required for idle tuning but I tuned for that anyway and it would have been down to about 150 ppm. Though I know that the EGR can rob power and most tuners block it off... after my tuning session and realizing how much I had to lean out my fuel map, I'm going to incorporate my emissions tuning so I can save on gas at cruising loads.
The AEM allowed me to control the EGR via RPM and allowed me to set the duty cycle and max duty and I varied it on the Emissions Diagnostic dyno in real time to get the emissions down.
One thing I can say... without an EGR, you will NOT pass emissions in Canada unless your car has some other means of reducing NO output. I had to tune my EGR to run at 91% duty to pass emissions. The EGR really gets a workout...
I will eventually get to a dyno and tune for power but for now, I'll tune for Air Fuel Ratios that make the most sense with street driving and fine tune the existing maps.
Another thing that makes me glad that I eventually went with an AEM, is it's ability to custom control various things as long as they are connected. I can change the coolant temp when the fan comes on and off. The EVAP systems in the Accord are wired up but but disabled by default on the AEM. I referred to the Service manual and enabled them all. I can control these switches by MAP load, RPM, Coolant temp, vehicle speed and any combination. i.e. I have my EVAP purge activated only above 2000 RPM with loads over 40 Kpa (usually accelerating) with Coolant temp above 75 and Vehicle speeds over 25 Kph. I do this as the EVAP purges fuel vapor from the fuel tank which richens the AFR which is best done during accelleration so I don't have to add more fuel to my fuel maps... Awesome!
I'm going to have my engine bay cleaned and I'll post up some pics. I've got some posts on the AEM forums if anyone wants to see how I configured the EGR functionality.