Tuning: What are we actually changing?
Lets talk about Timing Map A. (taken right from U-Tune)
When adjusting values, My ultra gauge shows my timing advanced value. from what i have noticed is that i have not needed to change any setting on MAP A because my setting are staying right around 20 deg advanced.
The stock system is dynamic and it is constantly adjusting the ignition timing to keep it as far advanced as possible and keep it right at the knock threshold. This gives you the best performance and the best fuel economy.
The knock threshold is the point where there will start to be some spark knock. The engines knock sensors pick up spark knock and when the ECU sees that spark knock is starting to occur it will reduce the ignition timing slightly. Then after a programmed period of time will start advancing the timing again until it sees knock and the process repeats, many times a second. Just remember the ignition timing is dynamic. This means it is constantly self-adjusting and the ECU keeps the timing right at the knock threshold.
Now lets talk about some things that affect the knock threshold. In our test
engine the ignition timing will usually be about 20 degrees advance at Wide Open Throttle (WOT) and redline. Variables that affect the knock threshold are; octane level of fuel, the fuel mixture, induction air temperatures, engine temperatures, compression ratio and so on. Now we stuff in 6 PSI of boost in this same engine with a roots style supercharger that builds boost as the engine RPMs increase. The ECU is now reporting that the ignition has dropped to 14 degrees of advance with a reduction of 6 degrees. With forced induction installed on our test engine pushing in 6 PSI the cylinder pressure has increased and that has made the cylinder charge more prone to knock. This causes the knock threshold to be much lower then on the stock engine. The ECU is still doing its dynamic ignition timing adjustments, and has self adjusted the ignition timing down to the new knock threshold.
You might get the impression that the ECU can handle the ignition timing all by its self with a forced induction conversion. It might, but if it cannot, it may lead to an engine failure. The problem is that the stock ECUs are not programmed to run properly with a forced induction conversion and was not intended to do so. Because of this, there is usually a very limited amount of adjustment range that the ECU has to adjust the ignition timing. When that range is used up, it cannot retard the timing any more, and if you require more adjustment then the ECU can work with, problems can result in engine failure. When tuning the ignition timing. your goal is to restore the ECUs internal adjustment range so it will have sufficient control authority to prevent boost induced spark knock. Remember in our stock test engine it was 20 degrees advance at WOT and full RPM? Then we boosted it with 6 PSI and it dropped to 14 degrees. (no direct correlation with boost pressures, 20-6=14) We have used up 6 degrees of its internal retard range. What if it only has 7 degrees available and you go boosting on a hot day? You can easily use up what is left and drive down the road knocking and pinging and destroying your engine. Our goal in tuning the ignition system is to restore the ECUs full internal adjustment range so you will have a sufficient safety margin. We call this the safety window.
You do not want to have all ZEROs past the point of max boost just incase
something goes wrong and you have a boost spike, you will not have enough retard needed. Populate the rest of the boost section of the table using the same concept all the way to the end of the map. Write that new map to the
Performance Calibration Unit.
Lets talk about Injector controller MAP B
This Map is mainly what people are talking about when they mention AFR.
Map B controls the time (in milliseconds) that the 7th injector is spraying fuel. By adjusting the time duration at which it sprays and depending on what RPM and Boost pressure, we are able to change the effective AFR numbers.
Adjusting values on the map
Its easiest to have a way to record the screen on your computer as you make a couple pulls, and some way to record the AFR numbers as well corresponding to the cell values.
Within MAP B we will click on a value cell that we want to change. Then change the number only by a few .1 increments, it does not take much to change the AFR. Proceed to make the necessary changes to the map corresponding to your AFR values, RPM and PSI.
Full Throttle Adjusting (OPEN LOOP)
EXAMPLE-so say at full boost my AFR is reading 12.6 and I would like to be in the 11.5 range. We need to increase the number in the cell value to change the AFR. The current number is 1.5 and changing it to 1.8 might get us there, to check our changes we would need to turn the car off, load the new map with this change and make another pull to see what value we are now at. Repeating this process multiple times until you reach the AFR closest to 11.5-12.0 at WOT
once you have made the adjustments you need to load the newly adjusted map onto the AIC controller.
1. Turn off the car (but the ignition to the ON position to give power to the AIC)
2. In the upper left corner click WRITE DATA TO ECU to load the map.
3. Click yes write data to AIC (it says something like that) the map will load after a few moments it will finish.
once the screen disappears, your newly adjusted map has been loaded onto the AIC. Make another pull and view the changes. If you are seeing values from your gauges that are not normal or you experience lag from the engine, continue by making proper adjustments to map A or B.
When you are satisfied with your AFR numbers, Save the new map (be sure to use SAVE AS) and name it by something you can remember.
Part Throttle Adjustment (CLOSED LOOP)
Closed loop- As the vehicle is running, the ECU is reading values from all sorts of sensors and making adjustments as needed. This is great for efficiency and smoothness. The downside to closed loop is ECU freaks out when values are outside of its tolerated range. As an example; The computer wants 5-7 and your giving it 3. It will make adjustment to get back into the 5-7 range.
Only certain year vehicles are able to make part throttle adjustments to the AFR. (96-98)
A big problem with our vehicles is the lean condition at high gear low RPM. this is when Ping is most common in closed loop. To fix this, we need to turn the injector on sooner to reduce Ping.
(Ping or Spark Knock, - The fuel-air charge is meant to be ignited by the spark plug only, and at a precise point in the piston's stroke. Knock occurs when the peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. )
This Concludes the basis of tuning URD AIC controller. If Anyone has any questions, please feel free to comment, share maps and discuss problem areas.
RR Racing tuner
Linear Mode
