Q: Bad pcm?

asked by on June 26, 2016

I have a 2000 f250 5.4 2v it runs horribly I've connected a snap on scanner to the Pam and it shows no codes but the long term fuel trim on the right bank shows -25 and the left 20 I have replaced coils and plugs and gapped the plugs when I perform a koer test the codes are for right bank running rich well I can unplug all injectors on the right side and it still says rich I've replaced both o2 sensors same code I tested the injectors to see if they were stuck open they weren't I can unplug the crank position sensor and not have a code I've run the truck for long periods of time and the scanner only says obd-II system check incomplete I have run it long enough to complete a system check I need to know if my pcm is bad due to no codes and making the right bank run lean even with the injectors unplugged and there was no change in the engine

If you can run your engine, with the fuel injectors on the right bank disconnected, it is not your PCM (ECM). By disconnecting the injectors, the computer cannot put fuel in without opening the injectors.

You need to check the fuel pressure to see if your pressure goes up to specification and stays there after the key is off. If you have immediate leak down of pressure you need to check if the fuel injectors are stuck or leaking. If you remove the fuel injector line with the injectors attached you should see one of them leaking.

Replace the injector and then clear the codes. Monitor the short term fuel trip and you should see it start to go back to normal.

If you need assistance with this, enlist a certified mechanic who can perform the necessary checks to properly diagnose this issue and replace your fuel injectors if necessary.

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