“How to Tune Idle in AEM Series 2”

Final Project: Technical paper

Vlad’s Performance Engineering

4/26/2013

By: Vlad Yevtushenko

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AEM Series 2 Idle Tuning

Table of Contents

Abstract………………………………………………………………………..……pg. 3

Glossary…………………………………………………………………….………pg. 4

Getting Started………………………………………………………………….…..pg. 5

Pre-tune steps……………………………………………………………………….pg. 6

Tuning Idle……………………………………………………...…………………..pg. 7

Works Cited………………………………………………….………..……………pg. 12

Three reviewers…………………………………………….………………………pg. 13

Professional review……………………………………….………………………..pg. 14

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Abstract

Every individual owning a vehicle with the AEM series 2 ECU or something of similar nature runs into a problem or two almost guaranteed. Most of the complaints that are heard include either the vehicle not starting or poor idle characteristics. The OEM manufactures are great at getting the car to start and idle, but once you start doing modifications to your car things are not so easy. This article will focus on solving one of your major problems. Extensive research has been done to ensure that the idle tuning process goes as smooth as possible, and makes your experience a pleasant one. AEM user manuals, EFI University documentation, and extensive personal experience on my own vehicle have been done to ensure the most accurate and helpful information is included. After the research was combined and translated for your understanding I was able to present to you a “how to” document on tuning idle in your AEM Series 2 equipped vehicle.

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Glossary

AEM- Advanced Engine Management. Performance company based out of California.

Boost- Pressure above atmospheric that can be achieved by a turbocharger or supercharger to increase engine performance

Dynamometer- Tuning tool that allows a vehicle to be strapped onto it to simulate road conditions. The dynamometer is a useful tuning tool because it can also display power and torque output.

ECU- Electronics control unit. The brains of an automobile

Tuning- Process of programming an ECU to operate an engine efficiently and properly.

RPM- Rotations per minute or engine speed.

VPE- Vlad’s Performance Engineering

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Getting Started

Before getting started on the idle tuning process we have to make sure all the needed sensors are working properly. In order to have a good idling car you will need an idle motor, coolant temperature sensor, air temperature sensor, O2 wideband sensor, and throttle position sensor. The idle motor is what allows air to enter your engine while your throttle plate is closed. Tuning idle without an idle motor is possible, but you can achieve much better results using one. The coolant temperature sensor tells your ECU how cold or hot your engine is. This is important because on a cold engine you will want your idle RPM to be higher and slowly drop the RPM when the engine warms up. It is also crucial because a cold engine requires more fuel to operate and after it is warmed up a leaner air fuel mixture can be used. One of the last sensors you have to check is the intake air temperature sensor (IAT). This sensor tells you the temperature of the air your engine is breathing. Once again colder air is denser air and requires more fuel than hot air. The last sensor you have to check is the O2 sensor. It is preferred that you use a wideband o2 sensor in order to get more precise displace of air to fuel ratios (AFR). AEM sells the wideband sensor and gauge for a very affordable price. You will need to install this sensor according to the instructions and make sure to connect the proper wire to your ECU so that the air to fuel ratio is displayed on your gauge and your ECU. This will allow the ECU to make corrections based on the AFR. The image to your right will show you where to look to ensure proper operation of the mentioned sensors. The displaced channels can be found by clicking the “Idle” tab found at the top. If the values next to said sensors make sense and change according to temperatures outside you can assume they are working properly. If you suspect one of the sensors are not working properly refer to your owner’s manual and get the problem corrected before proceeding.

(AEM Electronics et al., 2013)

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Pre-tune Steps

Ensure your vehicle starts and somewhat runs before tuning your idle. If your vehicle does not start please refer to the “How to tune startup in AEM Series 2” document before proceeding. This document can be found by contacting VPE.

Start by going to the tab at the top of your screen called “Wizards”, then “Set Throttle Range Wizard”. A dialogue box named “Set Throttle Range Wizard” will pop up. You will be able to see the voltage from your TPS sensor along with two buttons named “Set TPS Volts Min” and “Set TPS Volts Max”. See the picture below for reference.

Next, we will look at the “idle options” table. This table will have to be set up correctly in order for your idle to function properly. I will go over most of the important options you have to set, but the other options can be explained by the help window found in your software. This window can be found by clicking on the option you are interested in and then clicking “help” at the top proceeded by “tuning explanation”. Let’s start by looking at the image below. The first and second items listed refer to when your engine should be idling. The current settings tell the ECU to idle anytime it’s above 400 RPM and below 1700 RPM. Aside from that criteria the ECU also needs to see the TP position as less than 2.3% and turn off the idle function once the TPS sensor reads over 2.3%. This value needs to be set 1 or 2 percent above your normal resting

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idle position which can be found in your “idle channels” window with your foot off the throttle. The “Idle FB Min”, and “Idle FB Max” options are what tells your idle motor how much control it has. The -16.4 value is the maximum percentage amount the ECU can take away to maintain your target idle. The 34.4 value is the maximum percentage amount the ECU can add in order to maintain target idle. The next two options are set to -100, and 100. These options are the RPM you are allowing the target idle to be off by. So if your idle is set to 1000RPM and your engine is actually idling at 1050RPM the ECU won’t make any changes. Once your actual RPM and your target RPM are off by 100 RPM or more than it will take the necessary actions to correct it. For a heavily modified engine 100 is a good value to use. Most factory engines you can use 50 or 75 for a more precise idle. The rest of the options are related to the speed of your idle correction and can be further explained via the AEM software in the help menu. Those values can be left alone unless you run into idle problems in the future.

Tuning Idle

Now, we can finally start tuning your idle. The first thing you will need to do is set your “Idle FB Dead Bands +/-“ to -3000 and 3000. What this does is tell your ECU to make corrections to your idle when the RPM is off by 3000. In other words you are just telling your ECU to not make any corrections. This will allow you to calibrate your tune as precise as possible so the ECU does not have to work hard to correct the idle RPM.

Next go to your “Ign vs Idle RPM” table and zero that out. This table, when set up correctly, will help maintain the idle by advancing or retarding the ignition timing. Increasing ignition advance tends to raise the idle and lowering the ignition advance or retarding it tends to lower the idle RPM. Right now we don’t want any correction so we will leave it all at zero as shown below.

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After that step is completed, we will give some attention to your “ignition map”. The table/map represents your ignition timing throughout your entire engine operation. We will focus on idle. Most engines will idle between 500-1600 RPM and between -5 and -15 psi. I have circled the region you should pay attention to. You will want to leave your idle ignition timing at whatever your base map is set to which should be between 10-18 degrees. The idle region should be the RPM at which your car idles when it is fully warmed up. Ideally, between 800-1100 depending on how rough your engine runs. From 1100 and up you want your ignition timing to gradually go up to your “cruising ignition timing”. This can be different for each engine but it’s always a value much higher than idle. Refer to the pictures below to understand what I mean by the smooth transition.

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Basically, just make sure that your ignition timing does not have any large or abrupt changes in it. Remember more ignition advance will raise the idle and if there are drastic changes your idle will oscillate and tend to shoot up when it reaches those large numbers.

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Next, let’s take a look at the “RPM Offset vs TPS” table. This table is used to provide better drive ability in stop and go traffic. What this table does is raise your idle by the set RPM depending on how much you press your throttle. So basically, once you attempt to move your car from a stop the idle will be bumped up to a higher number so that you have more engine speed and not stall your car. Some vehicles just leave this all at 0 and have no problem getting the car to move, but for ease of driving you can set your table to something like the picture below. Just make sure that your slope does not start going until your throttle value is above your idle value. In other words, if your TPS resting position is 2.3% make sure your upward slope starts after 2.3%.

Next, we will start adjusting the tables that are the most crucial to your idle. Start by going to your “Idle Target Base Table” and setting it all to 1400 RPM. This way no matter what the temperature of your coolant is, you are requesting that your idle be at 1400 RPM. After you do this you may notice that your current RPM speed may not be at 1400, but your “idle target” RPM should be at 1400. You can see these values in the “Channels- Idle” box in your software. Now, in order to get the RPM you are requesting you have to adjust the “Idle% vs Target” table.

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This table tells your idle motor what position it needs to be at in order to maintain the set idle target RPM. If your idle RPM is not at 1400 like you are commanding it you can go to the Idle% vs Target table and click + or – on the corresponding dot at 1400 in order to raise or lower your idle. The table below helps illustrate what needs to be adjusted. Once you have adjusted the region that is circled in red and are maintaining an idle of 1400 you can move on to the next step. If your engine does not want to idle at 1400 you need to address the issue that is causing this. Make sure that your AFR is reasonable. AFR should be stable and between 13.0:1-15.0:1. Ideally, you want your engine to idle at 14.7:1. Also make sure your ignition timing is stable. You do not want it jumping from around 10 degrees otherwise your idle will not be stable. Now you can move onto the next step. Set your “Idle Target Base” table to 1300 all the way across and proceed to repeat the steps. Like before go to your “Idle% vs Target” table and adjust the 1300 RPM region until your engine RPM matches your target idle RPM which should now be 1300. Do this with 1200, 1100, 1000, 900, and 800 RPM. You can go as low as you want depending on what your engine will be idling at. Each time you drop in RPM make sure that your AFR is close to stoichiometric (14.7:1) and your ignition timing is not jumping around. At this point your “Idle% vs Target” table may look jagged and not smooth. You can highlight your lowest calibrated dot all the way until your highest calibrated dot and press the letter “H” on your keyboard. This is the hotkey for the “interpolate” function which will make your transition smooth and make your table look similar to the one pictured. Your slope may not be the same as the one pictured so do not worry. You can verify that your tune is good by going back through the different idle targets. Just highlight your entire “Idle Target Base” table and go back to 1400 RPM. If your engine speed jumps to 1400 you know your idle motor position was properly tuned.

Now that you are done tuning the most important part you can move onto the next steps to ensure you get a smooth idle. In order to get a higher idle on a cold engine and lower idle on a warm engine you can set your “Idle Target Base” similar to the one pictured to the right.

The next step is to set your dead bands back to

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something other than +/- 3000. For a rough engine I use 100 and a smoother running engine 50. This step essentially turns your idle feedback system back on. Now it will adjust the idle motor position the allowable amount you set earlier in order to maintain your target idle. If you are satisfied with the quality of your idle you can leave your “Ign vs Idle RPM” table all zero like we previously set it. If you want extra control and feedback for an even smoother idle you can set your table similar to the one pictured. Raising the ignition when idle RPM fall low or lowering ignition when idle RPM is above target. Do not make these changes to abrupt or large otherwise you will be doing more harm than good using this table.

A few other helpful options in maintaining a nice idle can be found in the “AC Idle Trim” option table. These options help your car continue to idle when you turn on your AC. Because the AC puts extra strain on the engine it is crucial that you adjust for that extra load. The first option is the “AC Min RPM”. Below this RPM the AC compressor will not turn on. This ensures that your compressor is not activated while you’re trying to start your engine or when you are close to stalling. The next option is “AC idle Load Comp”. This percentage value is the amount of duty to add to your idle motor in order to maintain your target idle speed. Basically, this is the value that will be added to your “Idle% vs Target” table. “AC On Delay” is in seconds and allows a certain time to pass before your AC compressor actually turns on. This is done to allow time for your idle to go up before the extra load is added to your engine.

Work Cited

AEM Electronics (2013). AEM Tuner (Version 2.98) [Software]. Available from http://forum.aempower.com/forum/index.php/topic,26751.0.html

Yevtushenko, V. (Producer). (2012, Feb 22). How to: Tune Idle in AEM Series 2 [Web Video]. Retrieved from http://www.youtube.com/watch?v=4CfP-W5bu5c

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Reviews

Vlad has created a very clear and concise manual that makes it simple for any beginner to tune their vehicle for a proper idle. All of the anticipated problems that could arise during the process are anticipated for and are addressed clearly in an understandable and informative manner. I would feel comfortable using this as reference material for this procedure.

Luke Farrell

Automotive Management maj.

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This is a great how to with clear step by step instructions. It is simple enough that a first time tuner could get their car to properly idle, but goes into enough detail to teach some tricks to even the most experienced calibrator. I would use this as a reference when tuning vehicles in the future, and would recommend it to others struggling to get their car to idle.

Chad Street

Engineer at Magna Electronics

As an owner of a vehicle equipped with an AEM Series 2 engine computer, I found Vlad’s “How to Tune Idle in AEM Series 2” to be very helpful and informative. To new users, the AEM software is complex, with settings buried in menus and almost hidden with the progam’s dozens of dropdowns and popup boxes. Vlad’s document clearly describes how to properly set and tune idle, a critical engine operation. AEM offers little support documents on the subject, if any. The screenshots in the document are very effective, and help to illustrate exactly what is happening. The explanations of acronyms the software uses and example settings are also helpful to have. I will be printing Vlad’s paper, and using it as a reference material for years to come.

Dan Marcus

Marcusd1@ferris.edu

Professional Review

Vlad has done his research on AEM’s products. Since the majority of our products are on built engines that are completely different from each other, every engine needs a different calibration to be properly controlled. It isn’t easy to relay tuning instructions towards everyday customers and Vlad’s approach at idle tuning on one of our systems nailed it. We’re always happy to get feedback from users like Vlad to make our products better!

Sam SanterreEngine Management System Development EngineerAEM Performance Electronics

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310.484.2322 ext. 215