24# injectors question

BlackSunshinelx said:

I would like to throw in my Cobra ECM

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It's a step down to swap out your current Mass Air computer for a Cobra ECM. There's nothing performance about them. They were programmed to make a good engine combo meet emmissions. Only benefit of them is they are programmed for 24# injectors.

If i were you, i'd stick with the computer you have no and get a MAF meter programmed for 24's

BlackSunshinelx said:

WEll i have the meter for the 24#ers and i got the cobra ecm because its pretty much a cobra spec motor.How low should i go for the pressure?

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Well you can't use the meter for 24's and the Cobra ECM together because the cobra uses a meter calibrated for 19's and changes it to 24's internally. If you wanted to use the Cobra ECM, you would need a meter calibrated for 19's.

You would be better off staying with the ECM you have now. The A9L and A9P are the most aggressive stock mustang computers. The cobra would be a step down.

39psi is stock pressure. How can you tell you are running rich? The computer can compensate at part throttle conditions by adjusting the injector pulse width. The only time it has no control is WOT when the injectors fire at whatever fuel pressure is set at. If you lower the pressure you will run leaner at WOT.

Part throttle though will be adjusted for. If you run rich at part throttle, lowering the fuel pressure will do nothing as the computer will signal for the injectors to just stay open longer. After a while you will be back to square 1. If you lower the pressure enough, you will be at 100% duty cycle which is not good.

WHat is causing the rich condition? o2's brand new? ANy check engine codes?

I would go for a custom burned chip anytime over a Cobra ECM. With the chip, you should return to a stock meter set for 19's and burn a chip adjucting for the 24's. Thats the correct way to do it. Sometimes, calibrated meters can cause small problems. With all the advances and ease of chip tuning, guys should really move away from calibrated MAF"s and program the injector size into chips.