point5chink

I just installed new 1680cc bosch secondaries and i cant tell if they are working correctly. First of all, I have a AEM pro ecu and i dont think there is an easy way to scale the map for changed secondaries. Now, when the secondaries are supposed to come on, my car bucks and kicks and shoots fire, but my O2 sensor is saying the AFR is like 14-15. This to me makes no sense...if its shooting fire shouldnt the AFR's be 10 or lower? SO which is it...secondaries coming on too strong and running super rich and shooting fire or not coming on and leaning out my afr's?

Monkman33

iTrader: (28)

I'd post this in the AEM forum.

point5chink

no one will ever respond in there! besides, this seems like a pretty general question as im not asking anything about the EMS. All i want to know is kicking and shooting fire a better indicator than my O2 sensor?

point5chink

ok, maybe my injector lag settings are wrong? Would this cause this kind of a problem?

maxcooper

Oxygen sensors don't measure mixture accurately when the engine misfires, so be mindful of them when using the readings as a diagnostic tool. My guess is that you are getting too much fuel. If they weren't firing, the car would just stumble hard without the exhaust pyrotechnics.

You need to find a way to configure the AEM for the larger injectors, which may be different from actually scaling the map, considering that the primary injectors did not change and the transition point may not be at a fixed point. It isn't at a fixed RPM in the stock ECU, for example, which is the main reason you can't use a S-AFC to correct the mixture for larger injectors. What settings does the AEM have? It seems like it would have to know the relative sizes of the injectors so that it could deliver a consistent amount of fuel during the injector transition. If you don't know how to configure your FI system, take it to someone who does. A mistake could be very costly once you start boosting.

-Max

point5chink

ok, so here is the answer. There was two parts to this problem.

First part is that the injector lag wasnt set properly. I fixed this by changing the transition point to somewhere i could reach by just revving my engine in neutral. Then i reved it and adjusted the injector lag until the O2 sensor was reading super rich.

Second part is the injector driver on the aem seems to suck. It only handles 1.5amps. I had 3.2ohm resistors with my bosch injectors. My car seems to run at about 13v-14v so this was overloading the driver when it was at longer pulse widths. Switchign the 3ohm for a 10ohm 10watt resistor and then setting the injector lag fixed everything. Now the injectors come on smooth and im getting a nice rich fuel mixture!

My car is now a one way trip to boost heaven