Running megasquirt ecu, did trackday yesturday all well till car started to run weak on boost, checked all vacuum pipes and fittings. Reloaded old map in but still same problem now stuck. Any sugestians welcome. When this is happening the afrs are jumping from 11.5 to 19 and car is stuttering.

Fuel filter blocked?

could be loads of things. check the easy stuff first. fuel pump or fuel pressure regulator, fuel filter, then things like injectors and injector driver in the ecu. are they high z or low z injectors?

Fitted new filter two weeks ago. Running low z injectors.

[Edited on 30/7/12 by madteg]

Mine did that when the vacumn/boost pipe came loose, the turbo spools up and overboosts hitting the configured overboost limit then the engine cuts out, boost drops and it fires up again, result car leaps forward and stutters.

So check your overboost setting is not very close to the boost you are running and that the wastegate is operating correctly.

Regards Mark