Before I get into the problem I'm having, here is what I'm running: 2002 Honda S2000 with built engine, Full Race Exhaust with GT35R turbo, AEM 1052 EMS, AEM P&H injector driver, Precision 1000cc injectors, and custom ITB intake. The car was tuned by RRev Motorsport and ran great, putting down 585 HP to the wheels. The engine has less than 1000 miles on it. While driving home one night, the engine started to sputter and not make any power. As soon as the engine revs got to about 3000 rpm and still in the vacuum area of the fuel curve, the AF ratio jumped to about 1.4 lambda and the car quit making any power. The problem is intermittent, but it occurs about 80% of the time. The other 20% it runs fine. Yesterday I took the car for a 20 minute drive and everything was good. Today I couldn't get it out of the driveway. Even with the car in neutral and revving to about 3000 rpm or above, the AF ratio goes way lean. So far I have changed the MAP sensor (GM 3 BAR), the fuel pump, and the plugs. I sent the injectors to RC Engineering for cleaning, but the problem continues. Anyone have any suggestions as to where to explore next?

 

The AEM EMS? Maybe its bad.

 

Send your AEM map to another tuner along with some data logs and see what they think about it. Sounds like something is up with the MAP or maybe (but unlikely) the EMS. Also make sure your harness going to the EMS is screwed tightly into the EMS.