popping at idle 750 saturated open and closed loop

joeb · Post by **joeb** » Tue Sep 12, 2006 3:53 am

I cant get my gsr to idle well with these 750cc saturated injectors.I tune in open loop and try to make it idle at 14.7 and it pops/missfires.It doesnt matter if i swith to closed loop.The only way it will idle well is if i tune it to idle at 12.3 or so and then its ok.Im using an aem uego downstream from the factory o2 sensor and tuning with an s200 with a 3bar map sensor.

Post by **Spunkster** » Tue Sep 12, 2006 9:27 am

You must remember that a/f readings at idle will not be the most accurate since there is very little flow in the exaust. The farther down the wideband is installed the more inaccurate the reading. Also having a Turbo will change the dynamics of how well the wideband reads at idle. Do you have a full exhaust?

joeb · Post by **joeb** » Tue Sep 12, 2006 12:34 pm

I do have a full 3 inch exhaust.My wideband sensor is mounted exactly where the second o2 sensor would normally be.I think i may have discovered what the problem is though.I am running 750 cc saturated rc injectors and rc does not recommend anything over 43.5 psi and i am running 46 psi at idle (hose connected).I was able to improve the popping when i turned the fuel pressure down slightly( i cant go any lower than 44 psi on the b&m modified oe regulator).So i ordered a new aem regulator and ill know for sure tomorrow.

joeb · Post by **joeb** » Sat Sep 16, 2006 5:26 pm

Well problem fixed.I simply installed an aem fpr and set my fuel pressure lower(40 psi) and it now idles perfectly!So for anyone who is trying to run large saturated injectors you must keep the fuel pressure low at idle(low duty cycle needed for idle) or it will have a lean missfire due to high fuel psi stopping the pintle in the injector from opening.