I have an IO360 with rear mounted Bendix.(200HP), 1 regular mag and 1 rose electronic ignition, In a tightly cowled Glasair II. When the outside air temperature gets warm, IE above 60 deg F the engine idles rough and occasionally pops. It seems to get worse as the temperatures go up. It does not seem to do it at full power , only below 1800rpm. It does not seem to matter if the boost fuel pump is on or off, if the engine is running on the mag, elect ignition or both. I don't see much fluctuation in the egts when it is popping. Could it be fuel boiling? I have put fire sleeve on all the lines, including the spider to the injectors, and I have a cooling shroud on the fuel filter and the pump. any suggestions?

Keith,

 

1. Check Idle Mixture setting

 

2. Check for induction system air leak - do you have an engine monitor? If so, is the problem isolated to one cyl?

 

3. Check plugs and harness -