Hope the engine tuning is going as well as it was the last time we talked on the phone Chris.  Didn't see anything wrong with your comments.

Also been working with Bobby Hughes on his tuning problems and have his unit on the bench.  He had a double rpm reading on the EM3 which was clearly my mistake (wrong engine type selected when programming it). 

But the other tuning problems are still not understood completely.  Whenever there is this much trouble getting the engine to run smoothly over the entire range of throttle settings, it almost always turns out to be one or more basic problems.  In the case of Chris's engine, it was the fuel pressure regulator connection and understanding the programming procedure (which is very understandable given that this is not simple stuff). 

The most frequent mistake in tuning is not getting the expected result at an early step and then moving on without finding out what was wrong at the earlier step.  I can't emphasize this enough, if things don't go right at any given step, stop and figure it out or ask for help.   Going on before doing this leads to compounding the problem and a lot of frustration.   Builders with some knowledge of EFI tend to be even more prone to this than beginners.

Have been studying Steve's EC2 chart (attached) a lot and finally got the overall picture of what it is showing.  But there are a few pieces of the puzzle I don't know.  The main point is the label at the top (RPM Threshold (10.5").  The question is:  Is that where the threshold is set or is that saying that this is the apparent threshold as the EC2 is actually working?  The default rpm[table]threshold is about 14" but this is a programmmable parameter in the EC2 and it can be set most anywhere.  If it was in fact set at 10.5", the EC2 is working exactly as designed. 
The "Expected" bar at the bottom of the chart shows what it should do if set near the default value of 14".   I have not been able to reproduce the same MAP address behavior as Steve got when RPMThreshold is set to 14"

   Also note that the problem areas (where the rpm goes unstable) are when the engine is throttled below what most builders use for idle speed.  My guess is that this is where the RPM table has not been programmed.  Note that the table data values are not shown on the plot.  That data would show why the rpm went unstable I think.  The lower map table addresses below the stable portion should be set to similar values to the good running places just above them.  These are hard to adjust because it is sometimes difficult to get to them without the use of an EM2/3.

It was my understanding that Steve was able to tune the lower map addresses and get the engine rpm smooth in the unstable areas so it was not an operational problem even when the rpmthreshold was working as shown on the chart.  Let me know if this is not correct Steve.

Bobby concluded that the chart illustrates what is causing his problems but I can't tell without more data.  I have made some changes in his program that I think will help (higher RPM range for the RPM table) but I'm still not certain that his very large primary injectors are not causing a problem  They are more that twice as large as the stock Renesis primaries.  I continue to urge builders to not go to 'hot rod' injectors.   Remember that the 13B can develop almost 100% power on the 2nd gen primaries alone (440 cc/min).  See David Leonards post on where he stages his turbo engine. 

Tracy (back to the grind)