PIGGYBACK COMPUTER INSTALLATION
This is for historical reference now. All of these systems have been removed. Engine will be operated by a Electromotive TEC3 ECU.
MSD Multi-Function Ignition Controller (8979)
Here is where I get into how I am tuning with the MOTRONIC 1.0. I am installing two piggyback computers, MSD 8979 and a APEXi S-AFC controller. With these I will be able to fully manage my A/F and timing parameters in the ECU.
The new Multi-Function Ignition Controller (part No. 8979) from MSD is an add-on control box that works with an existing ignition. The Controller serves up a long menu of functions such as a timing curve for the entire run, a launch retard ramp (small tire cars will like this feature), retard stages, three rev limits, different shift points for each gear, and even cylinder-to-cylinder timing.
APEXI S-AFC INSTALLATION
The A'PEXi S-AFC is a piggyback computer. This basically means that it cannot function without your stock ECU. The S-AFC uses a simple principal to do a very complex thing. It takes the signal from the stock MAF/AFM Sensor, and filters it, then passes it on to the ECU. The ECU does not know that the S-AFC is lying to it, so it goes on it's merry way thinking that the signal it is receiving is direct from the MAF/AFM sensor. This is an incredibly simplified explanation for what the S-AFC does.
DISCONNECT THE BATTERY NEGATIVE!
A variable voltage TPS is required to work with the APEXi. Luckily, the E34 with auto has one.
Installing the E34 TPS � The E34 TPS is a direct replacement for the stock TPS. Being that the E34 (automatic) TPS has 6 wires coming from it, you will need the complete wire harness from the ECU to the switch. Three wires will splice directly to our engine wire harness close to the switch. The Brown/Blue, Brown/Black and the Brown wires. These are your throttle closed (for the ICV) and the WOT signals for the ECU. An interesting note here, with the WOT wire disconnected, I gained 12 hp on the dyno. I also do not have the throttle-closed wire connected due to my idle being up around 900 RPM due to my cam. Now you need to run the shielded cable (which comes from the TPS and has three wires in it) from the TPS to the ECU, it is long enough. Now strip the shielding to expose the yellow, brown and black wire. The brown wire is a ground and can be spliced in to any brown wire from the ECU. Yellow connects to the Gray wire from the APEXi S-AFC. The black wire needs to be spliced to the Gray/White wire from the ECU. This is the 5V reference output from the AFM and will give you the necessary 5V to power the TPS.
Installation � we are going to be cutting and splicing ECU wire here. If you are the faint of heart, stop here.
I unplugged the wire harness from the ECU, this gives you more room to work. Also, remove the plastic tape from the wire harness to give you access to all of the wires. For the wire description, (example. Brown/Black) the first color is the color of the wire the second color is the color of the line on the wire.
Find the Gray/Yellow wire. This is the AFM Sensor signal wire. Cut the wire and strip both ends. Crimp the included male fitting to the wire leading TO the ECU. Crimp the included female fitting to the other end of the wire. This will allow you to bypass the S-AFC should the need ever arise.
Plug the male and female fitting from the S-AFC wiring harness in to the connections you just crimped to the ECU harness. Yellow to the wire from the ECU and White to wire from the AFM sensor.
Locate the Red wire. This is the ignition power wire. Splice in the Red wire from the S-AFC harness.
Locate the Black/Blue wire. This is the Tach signal wire. Splice in the Green wire from the S-AFC harness.
Locate the Yellow wire from the TPS cable. This is the TP Sensor signal wire. Connect too the Gray wire from the S-AFC harness.
Locate one of the large gauge Brown wires from the ECU. This is a tricky step so pay attention. Splice in the Brown wire from the S-AFC. Now move about an inch or two farther away from the ECU and splice in the Black wire from the S-AFC. This is very important. If you do not splice these wires in separately and it the proper location, the S-AFC will not function correctly.
Use wire ties to securely fasten all wires on either side of their connections. Use wire zip ties to route the "signal harness" back to the S-AFC connector. Finally bundle all unused wires. Don't worry about them. The S-AFC was designed to function on several different vehicles.
Reattach the Battery Negative.
Don't flip-out, it is only mounted here during tuning. Rest of time is in glove box.
Now you have your pretty blue and silver box installed. You need to configure it so that it knows what it is attached to.
Turn your key to the Run position. Do not start the engine! You should see the S-AFC power up and the A'PEXi logo flash across the screen. If you do not see the unit light up, ensure that the key is in the Run position (not the accessory position). If you still have no power to the unit and your battery has been reconnected, check all of your splices.
If your unit is fresh out of the box it should come up to the Main Menu as seen below.
1. Monitor
2. Setting
3. etc.
Press the down arrow until etc. is highlighted, then press the "Next" key. You will then see the screen below.
1. Sensor Type
2. Car Select
3. Grph Scale
4. Sensor chk
5. VFD Bright
6. Initialize
Highlight Sensor Type, then "Next"
1. Hot Wire
2. Flap
3. Pressure
4. Karman
Highlight HOT WIRE since the BMW uses a MAF/AFM Sensor. Then "Next"
In 01 Out 01
You will need to enter sensor "01" for both in and out. This will allow the S-AFC to know that kind of voltage to expect coming in, and what kind of voltage to send out. This setting uses a 5V reference scale and will work if you still have the AFM or a MAF. They both have a 5V reference output. Now press "Back" twice.
1. Sensor Type
2. Car Select
3. Grph Scale
4. Sensor chk
5. VFD Bright
6. Initialize
Select Car Select, and then "Next"
Cy 6 Thr
Set the cylinders to 6. The Thr arrow should point up and to the right. This tells the S-AFC that the TPS voltage is highest (appox 5V) at WOT.
Now press "Back" once.
1. Sensor Type
2. Car Select
3. Grph Scale
4. Sensor chk
5. VFD Bright
6. Initialize
Select Grph Scale, and press "Next"
Pr: 760mmHG~0mmHG
Ne: 7000 rpm
Cr: +-30%
Now we will setup the Graph scale for the display. Pr should be set at 760mmHg~0mmHg. This will give you the best range for the 5V MAF/AFM. Ne is the maximum RPM that the graph will read. Cr is the correction ratio. You can set it as high as you like, but I would leave it at 30% for now.
When you are done, press "Back" once.
1. Sensor Type
2. Car Select
3. Grph Scale
4. Sensor chk
5. VFD Bright
6. Initialize
The Sensor chk screen will display your voltage from your sensors.
This screen will show the voltage for the TPS and the MAF/AFM. It is easy to tell if you have the TPS hooked up correctly. If you punch the accelerator in you will see the voltage go up.
If you are on the Sensor chk screen press "Back" otherwise, select the VFD Bright, then "Next"
Day 99 Dim 50 Nig 20
Now we will set the VFD (Vacuum Fluorescent Display) Brightness. I prefer the settings you see above. They allow me to see the S-AFC without being distracting. If you want to see exactly how distracting it can be, wait until dark then turn the Nig setting up to 99. It will be bright enough to detract from safe driving if it is anywhere near your line of sight.
The S-AFC uses a neat little photo cell to detect the lighting conditions in the cockpit. This eliminate the need to wire anything in to your vehicles lights. It is a system that works extremely well.
When you are done playing with it, press "Back"
The last settings on the etc. menu is Initialize. This will return the S-AFC back to factory fresh. I would suggest leaving this one alone unless you really goof something up.
Press "Back" until you are back at the main menu.
1. Monitor
2. Setting
3. etc.
Now we will get to what you bought this thing for. Select Setting, then press "Next"
1. Hi-Thrtl
2. Lo-Thrtl
3. TH-Point
4. Ne-Point
5. Dec.-Air
Select Ne-Point, then press "Next"
Ne1: 1000 rpm
Ne2: 1500 rpm
Ne3: 2000 rpm
Ne4: 3000 rpm
Ne5: 4000 rpm
Ne6: 5000 rpm
Ne7: 5500 rpm
Ne8: 6000 rpm
Set the Ne Points as you see above. These are the RPM points that you will use to adjust the air/fuel correction. You may choose any that you wish, but I find that these are adequate to cover most adjustments. If you find that you have a problem area, you may make the gaps smaller in that RPM range. Just remember that you are limited to 8 points.
When you are finished, select "Back"
1. Hi-Thrtl
2. Lo-Thrtl
3. TH-Point
4. Ne-Point
5. Dec.-Air
Select TH-Point, then press "Next"
Lo 30% Hi 45%
This is where you select the split between the two correction profiles that we will setup. You can set this at whatever you wish. Basically how it works, is when the throttle is below 30% the Lo-Thrtl correction table is used. When the throttle is above 45% the Hi-Thrtl table is used.
When you are finished, press "Back" twice.
1. Monitor
2. Setting
3. etc.
Select Monitor, then press "Next"
I am not going to go step by step through this area. It is not BMW specific, and is covered well enough in the S-AFC literature. Play with it a bit. You can't hurt your motor with the Monitor menus. I prefer the digital display for 4 parameters. This gives me the maximum amount of information without cluttering the screen. There are several settings that allow you to display information in Analog gauge format, digital, and line graph format.
You have now completed enough of the configuration that you can safely start and drive your Saturn with the same level of performance that you previously had.
Please note, this next step should only be performed on a Chassis Dyno with a wide band O2 sensor, or with equipment to determine what the true A/F ratio is while monitoring for detonation such as the SDS A/F meter I have installed. Failure to do so may result in a blown motor. If you do not have access to either of the afore mentioned facilities, you can leave the Hi-Thrtl and Lo-Thrtl curves at 0%. This will simply have no effect on your current Air/Fuel settings.
1. Hi-Thrtl
2. Lo-Thrtl
3. TH-Point
4. Ne-Point
5. Dec.-Air
Select Lo-Thrtl, then press "Next"
You will see a screen that looks like this, except all values will be zero. The goal is to set the correction % as lean as you can without causing detonation.
To set the Lo-Thrtl curve we went back to the TH-Point setting, and set Lo at 100%. This ensured that the S-AFC was always using the Lo-Thrtl curve while we are setting it.
Hold the RPM at the level that you intend to tune. Start on the rich side of the line. Slowly adjust the correction leaner, watching your A/F ratio on the meter. At low throttle, I set mine to around 14-15:1 which is a little lean but good for gas mileage. Continue this for the rest of your RPM ranges.
I set the Hi-Thrtl settings a little richer due to the fact that that curve will be used only under load. I have used my old dyno numbers to set it to what I believe will be a steady A/F ratio through the rpm curve. I will get the setting perfect on a dyno.
THATS ABOUT IT FOR NOW. I will update this page when I get the car back from the dyno with new HP numbers.
