OBD II Fuel System Status Question

I have 96 Dakota 3.9 automatic that gives me less fuel mileage than what I believe I should be getting.

I have ensured that the plugs are in good shape,the plug wires are new, tires properly inflated, drive with a light foot, I have changed both oxy sensors. The truck runs fine and the OBD II is not generating any trouble codes. The truck recently passed the Calif smog test and passed by a very wide margin. I have ran liquid injector cleaner in the tank several times.

I obtained a Davis CarChip device so I could get a printed record of what is happening in regard to OBD readings. What I found out is that Fuel System #2 runs in open loop for a few minutes while the coolant temp is coming up, but Fuel System #1 is staying in open mode all the time.

Now I am an OLD shade tree hobby mech since Model A Fords were a common sight on the streets. Until now I haven't given much effort to understanding the OBD system but I now would like to increase my knowledge in that area, hence putting out the bucks for the Davis CarChip.

My guess, and correct me if I am wrong, is that Fuel System #1 refers to the injectors on Bank #1 and Fuel System #2 refers to the injectors on Bank 2. Can anyone confirm this.

Would a dirty or clogged injector in Bank #1 cause it to remain in Open loop? Is now the next logical step to have a professional cleaning of the injectors.

Old_Timer

Reply to
Old_Timer
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Step 1 Use a long handle screw driver put it on each injector, you should hear a distintive tapping as the injector fires. If one or two are week you will notice it right away. Run a pressurized fuel rail cleaner follow the directions. Recheck injectors if all is well thet was your problen, if an injector does not sound right replace it. Also buy an o-righ kist and replace all the injector o-rings while you have them pulled.

Reply to
Coasty

Thanks Coasty, I will try and see if Ican hear a bad injector.

Old_Timer

Reply to
Old_Timer

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