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Discussion Starter · #1 · (Edited)
I have a 2014 ST with a GTX2867R and accessory fuel injectors tuned by Freektune. Car has been having some miss-fires on startup in cylinder one and would get some pre-ignition around the 3k RPM range, made worse my cruise control driving around that RPM. Knock would stop when I varied the throttle a bit. Id get an engine tick when on the throttle, nothing when I let off. Engine compression was even across all cylinders. I figured it was an injector, replaced the number one injector with a new stock one. Put things back together and the car wont run smooth, threw a bunch of codes from MAP, Fuel rail pressure, cam shaft position sensors, ac pressure. I unplug the fuel rail pressure sensor, and MAP sensor and the car starts, idles smooth, gets rich and i cant apply throttle without the engine sputtering a bit. Things sound great when it’s idling like this. I double checked all my connector wires, even tried a new fuel rail pressure sensor with no luck. Any ideas, I’m stuck without a car now. Ive done all the work myself and never had any trouble like this.


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Check the spark plugs.
 

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Discussion Starter · #4 · (Edited)
Thanks for the responses. I had checked the spark plugs and coils before changing the injector. A mechanic friend of mine suggested putting the old injector back, it just didnt make sense to me since the car would idle smooth without the fuel rail pressure sensor and MAP sensor. I figured if the injector was the issue it wouldnt start or idle at all. What’s making me nervous are all the sensor codes it throws with the switches plugged in. Without the fuel rail pressure sensor and MAP sensor plugged in, those are the only codes thrown and it starts and idles smooth. I have a hard time believing that I caused damage to the harness some how, but it’s the only thing that makes sense to me at the moment. Regardless, Ill try to replace the new injector with the old and see what I get.

The reason i changed out the fuel pressure sensor is because I see it reading 150ish pounds when I know it should be between 1k and 3k depending on the RPM range.


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