Welcome to BMW 2002 FAQ

Wrap up on the build. Then more to come.

So... it has been quite a journey.  At more than one point I felt that I wouldn't be writing this for the following reasons.   1) 40MM DGAV carbs are significant for these cars.  There are many stories of a 38MM not running as good as a 32/36, let along a 40mm.  2) Could the injectors run efficiently down to the flow rates of a 2L? ( we can talk about this one a little later).  3) Would an adapter work for the stock intake?  Would it act funny?  Would the added height make a difference? 4)Would the sharp 90 degrees turn going into the intake pool fuel at the bottom of it?  5) Is there enough space for the fuel pump, filters et al. 6) Would there be enough exhaust flow to get an accurate AFR for the system to tune? 7) Would the dimensions of the EFI, be able to fit under the hood? 😎 What to do with the linkage.  9) Would I have vacuum issues?  Would it affect the brakes? 10) What sort of ignition advance should I run?.  Would a stock Tii curve be best in my 123?  11) Would the fuel fall out of suspension on such a large bore of intake and make it impossible to idle.  12) Would the Coolant Temperature Sensor work mounted correctly in the intake?.  13) How do I tune this thing?
So let me try to summarise here, what we have discussed over the past five other blogs — starting from the beginning. 
1) Equipment: I like the Holley EFI sniper.  It is a well-built unit, the parts, connectors, instructions and most importantly, support, is good.... except for one thing... the O2 sensor. 
 
O2 sensor   The 02 sensor is notoriously short-lived in many of these installs.  The issue is not limited to just my application.  They do not last long, but thankfully the replacements are about $60, and the chances are that you will be replacing one under warranty.    Fuel pump   I used a summit fuel pump rather than the Holley one, just because they seem to have a higher than average failure rate.  In all fairness, many people (including me still) do not plumb the return line properly into the tank.  You want to return the fuel using a proper -6 fitting, and have a short length of hose in the tank to return it to the bottom, where it doesn't froth the fuel.   If the pump pulls up this frothed fuel, it causes tiny little explosions (cavitation) f when the bubbles pop on the fuel impeller and cause it to fail prematurely.   Now that I have the system working correctly and I know it is going to be installed for good, I will have my fitting installed.    Fuel lines   I used summit fuel lines with Summit brand -6 fittings for the most part.  I didn't go high budget, but I made sure that the hoses were built well.  I also didn't use ethanol rated hoses as I won't have access to E85, and I run premium 92 ethanol free fuel.   I also give a bit of a squirt of Lucas fuel additive when I fill up to keep the valves and the combustion chamber clean and lubed... I don't think it could hurt.    Fuel Filter   I purchased a canister style fuel filter with a 40-micron filter and plumbed it between the tank and the pump.   Holley suggests at 10-micron filter after. I will pick one up and put it in when I finish the install of the -6 return inlet in the gas tank.      MSD 6a and Flywheel   In anticipation that I was going to do some performance upgrades, I installed an MSD 6a, and when I switched to a five-speed, I had the flywheel lightened.  The only effect the lightened flywheel may have is that it returns to idle quickly, due to less inertia, so the idle tuning was perhaps a little more difficult as a result.    The MSD 6a I would say is the most important thing to have installed for this build.  The EFI can put out a lot of fuel. The MSD I feel makes the tune a little more forgiving, for the simple reason that you get a stronger spark and better combustion.   I had flooded the car with the EFI when I was trying to adjust the startup parameters, so even the MSD is not foolproof.   There is a function in the software that allows you to floor it, and it will shut off the fuel when cranking, kind of like what you do with a carbed system.   Intake   Other than having the intake under the carb bored out to take advantage of the Dual 40mm( it is 41.5mm) inlets.  I had the intake port matched to the head.  For S**ts and giggles, I took a ball hone and smoothed out the inside of the runners (see the previous blog).  I am not sure that this made a difference, but when you are there, I don't see the harm in doing it.  This being said, many others much much more experienced than me said that smoothing out the intake would have the fuel fall out of suspension easier or earlier.  If you are concerned about that, then don't do it.   Or if you have the time install it stock and then pull off the intake hone it and see if you like the change.    Temp Sensor   I installed the temperature sensor in the intake.  The temperature does wonder quite a bit, especially in traffic.  After idling in traffic for 1-2 hours, the temp went to what I think is about 185 (2/3 of the way up on the dash gauge),  the intake stayed about 165.   After 2 min on the road, they came in line.  The inlet air temperature also went up as well, but I then realized that the breather had slipped off its base, letting engine compartment air in.  After I realigned it and snugged it up, the temperature now remaines constant.    Exhaust   I had what I think was a Stahl long header.  It was rusty and cracked at the collector.  I decided before the build that  I was going to replace it with something better.  I then decided to re-do my air conditioning, so that meant that a turbo was less likely; hence the I.E try y header.    Linkage   The linkage was the most frustrating at the beginning of the build.  I initially purchased a cable system and adapted it to be used with the linkage.   I think it was for a DCOE cable apparatus.  Regardless of what it was, it didn't work.  It was more of an on/off switch it stuck so bad.   So I had to build one.    I used the design that AustrianVespaGuy had for his EFI conversion.  I adapted it a bit.  As you can see  (pictures coming) it is essentially it is an "L" shaped bracket attached to the brake booster.  One end to the throttle rod, the other end to the throttle body.    I had my fabricator buddy press in a bearing to make it operate smoothly.  I had a heim jointed throttle rod, purchased from a fellow 02 member already,  so it made for a much better and easily modulated pedal.     It took a lot of fiddling, but it was worth it.  What is essential to do is make sure that the throttle returns completely.  Every time you start the EFI system it "0's" the TPS,  and uses that for the baseline.   This is essential for every function of the system that the opening for the throttle is exact, especially for idle.    If you don't then you get a high idle if it is stuck or other annoying behaviours that make it next to impossible to set the idle.     There are two return springs built into the throttle body itself.  There is a third one in the pedal box and a fourth that is stock at the point where the throttle rod meets the rod going into your carb.   My best advice is to make sure that they all are in intact and in good working order, even with that the TPS is sensitive sometimes to show 1% when the pedal is fully released.   Noise at the TPS is not your friend, especially so due to the small opening required to maintain idle on such a small motor.    Wiring/Electrical    Simply put,  do exactly what the instructions say.   Take your time, do it right.  I don't want to imagine how to troubleshoot this one.    This includes putting a little bit of shrink tube over the ends of the wires you don't use.    Going through the firewall wasn't pretty.  I have to go back and clean this up, and I am not sure what I am going to do.  You need about a 1" hole to fish through the wires going from the TB into the car, especially if you want to run the screen inside the car.   I ended up drilling two smaller holes side by side and then opening them up.    I haven't used any of the outputs, like the AC kick-down, or the fan controllers, but I do plan on using that in the future.  It will be a nice backup to have the AC fan turn on as a backup if the car is overheating.    Also, the EFI will accommodate the idle when the AC kicks in, and to help with passing power, it will temporarily shut off the AC when you floor it to pass, giving you extra power.... very cool (pun intended)    Tuning This brings me to the part that is by far the hardest to document Reading the balance of my Blog will show the path that I took to get to where I am now with the tune. I thoroughly encourage people to use this area to post their tunes and techniques on getting them.    In the end, this is what I did.    I put a bit of tape over the IAC inlet in the top, this is to isolate the influence of the IAC on your idle and mixture.  When in this mode, you can use the fuel table to tune manually.     Before you start going too crazy,  set up the idle fuel AFR.  Trust me when I say,  it should be at least 12.5.   It will overshoot, meaning not stopping at your set idle (between 800RPM to 1000 RPM idle,  go all the way to 0 rpm and bounce back.  This drove me nuts for weeks on end.  I thought it was a "false lean" because the data was showing when I closed the throttle the AFR would spike.   This had lead me down a false path of controlling fuel flow when the throttle was shut.    After the new header went in, I realized it was really lean, and not a "false lean".  Reading up on false lean is very helpful, essentially it is caused by fuel soaking the 02 sensor, and causing it to not see any air until it dries out.      I  digress.  Start by adding fuel, especially around the bottom left-hand corner of the fuel map (this is the area where it idles).      In a separate screen open up the screen for the data graphs.  Pick the "1000" pts from the drop-down in the top left corner of the screen.  This allows pulling back from the data and look at the overall pattern.    Select Target AFR, Actual AFR and RPM for now out of the choices on the left.  The Actual AFR should be spending a lot of its time close to either side of the Target AFR.     My problem with my first 02 Sensor from Holley, is that it was reading all over the place.  My Second 02 sensor was reading evenly, but incorrectly as it would always be reading 2.0 below the target, no matter what I did.  The third 02 sensor did the trick.  It tracked along the actual nicely and made life really easy after that.    So while the IAC is blocked off.  Set your actual idle via the throttle plate adjustment screw and get it about 50-75 RPM below your target that is set in the software (that is what some tuners say to do, I set my idle at my target).   So if you set your idle in the software for 900 RPM.  Get it to idle about 850, with your IAC blocked off with your AFR close to your target of about 12.5, or whatever you set it to in your target AFR table.    Adjust the fuel table manually, adjust the throttle screw until both are in balance and your AFR is on target.   If while on the data graph page, you see the TPS sensor read anything above 0. Turn the car off then on.  It will reset the baseline for the TPS and set it to 0 (it does this every time you start the car),  this is important since a lot of other functions depend on knowing the Throttle Position 
So you are now looking at the data graph screen.    Your AFR  should be close to where you want it.  Your RPM is about where you want it (perhaps a little low) and your TPS is at 0.  Stop the car.  Take the tape off the top of the throttle body that covers the IAC intake.    Start the car.    This is where my tune build works well but not perfect.    Your IAC should be between 2-10,  although I have a tendency to ignore it,  solely because it takes time for the IAC to react, and with a small displacement engine, it is hard-pressed to react and do it accurately (at least that is my theory now).   You can play with a setting that controls how fast it reacts.   I played with it and didn't see any difference in how the idle reacted.    Rev the car and see how it is coming down to idle.  My car has a lightened flywheel, so coming down to idle may happen faster then yours does.  Adjust your idle with the setting in the Holley and adjust the throttle plate as required to make sure it doesn't overrun.  I had to fiddle with this a lot, but got it working well.   
Tune specific notes:   I have locked down the learning, specifically around idle.  I will let it add more fuel around my idle, but not less ALA Austrianvespaguy's recommendation,  make a nice "flat spot" in your target AFR table where your car wants to idle.   This will make it easier for the system to find a stable idle.   the smoothing function in the software is your friend, but don't overuse it.   Intuitively you want to see everything smooth,  I don' t think that is necessarily correct.  To me reign in the changes by changing the 'learn' table.   It starts off at 100%,  meaning that the learn table can alter the fuel flow by 100%.  As you get closer you start reducing this down.   For the size of our motors,  20-30% is a healthy change.      Closed-loop change:  Keep this tight at idle. and open it up once you are in the throttle.   I locked my tune down.  If I opened it up too much, my idle gets a little weird and bi-polar.    Learn table:  Keep it tight at idle,   let it open up a bit at higher engine loads and RPM's    I am sure that there is more stuff that I am missing, but this is a good start.  I will update with some pretty pictures and a ride along, as soon as Vancouver digs itself out of some snow.    Next thing:  incorporating the Sniper EFI system to control timing. 

Dudeland | Wednesday at 08:42 PM
Holley Sniper EFI Conversion 1