Need help, P0175 code coming up.

[Project_Exploder]

I really need some help, code P0175 (system too rich (bank 2)) is coming up on my code reader. Please, someone that has had this problem point me in the right direction.

 

[manaen]

the first thing I would do is run a fuel pressure test, and clean the MAF. A bad FPR (Fuel Pressure Regulator) can cause a rich condition if the pressure is higher than stock spec.

 

[Project_Exploder]

Thanks, I'll do that asap.

 

[Turdle]

moved to the stock 95-01 sub forum.

 

[Project_Exploder]

Thanks Turdle, wasn't sure which sub-forum to put it under.

 

[2000StreetRod]

What engine?

I read thru your "My Ride" but it doesn't tell what engine you have.

I would look for something that only affects bank 2. A bad MAF sensor or fuel pressure regulator should result in P0172 and P0175. You could have one or more leaking injectors in bank 2.

For 1998, P0175 is set when long term fuel trim (LTFT) is less than 25%, short term fuel trim (STFT) is less than 10%. You might try disconnecting your battery to erase the Keep Alive Memory, then reconnect and drive the vehicle watching for the CEL to come on. The PCM should run the Fuel System Monitor as soon as closed loop fuel is achieved. Note how long it takes for the CEL to illuminate and under what conditions.

A bad bank 2 O2 sensor could result in an erroneous too rich report to the PCM. The PCM would try to compensate by decreasing the richness (injector pulse width) in bank 2. When it hits a reduction of 25% for LTFT and 10% for STFT it sets the DTC.

 

[manaen]

that's a good point, but I have had a truck that threw just a 175 from high fuel pressure, dont know why :shrug:

I would still check fuel pressure since it's only a 5min job and then pull all the plugs, that will help to identify if the problem is central to one cylinder. Note any cylinders that seem to be running rich. If there are no signs of a rich condition it is possible that the o2 sensor for bank 2 is bad (unlikely but possible)

 

[2000StreetRod]

pulling plugs good tip!

. . . I would still check fuel pressure since it's only a 5min job and then pull all the plugs, that will help to identify if the problem is central to one cylinder. Note any cylinders that seem to be running rich. If there are no signs of a rich condition it is possible that the o2 sensor for bank 2 is bad (unlikely but possible)

Looking at the plugs is an easy and inexpensive way to identify an abnormal rich condition. An excellent tip! Sometimes with all the electronics these days, I forget how I used to do it.

 

[Project_Exploder]

It's a 4.0L SOHC, and I will be giving all suggestions at least one try, unless they just sounds dumb.



And dammit, just noticed my elite membership ran out.....

 

[Project_Exploder]

Thank you everyone for the help!

It ended up being a dirty MAF and a bad spark plug, running like a champ now!



Again, thank you guys.

-Ducey-

 

[joseph dbennidetto]

the first thing I would do is run a fuel pressure test, and clean the MAF. A bad FPR (Fuel Pressure Regulator) can cause a rich condition if the pressure is higher than stock spec.

fuel pressure is alright, brand new MAF FPR doesn't leak. now what should I do. I got rich condition on both banks.

 

[2000StreetRod]

A leaking fuel injector can cause a rich condition but is probably unlikely your source of problem since both banks are running rich. The PCM adjusts the injector pulse width according to engine temperature and air temperature. I would think that a dirty MAF sensor element would result in a lean condition since it detects less than the actual air mass flow and you have replaced the MAF sensor. My guess is that you have a defective engine coolant temperature sensor or a poor electrical connection between the ECT sensor and the PCM. If the PCM erroneously detects the engine as colder than it actually is then injector pulse width will be excessive and the O2 sensors will detect a rich condition. Below is a ECT sensor chart of temperature vs resistance.

As you can see from the chart, as the temperature decreases the resistance increases. If there is an open circuit due to a broken wire or loose connector the resistance will be infinity and the PCM will think the ECT is extremely cold. Don't mistake the engine temperature sending unit for the dash indicator as the ECT sensor. The easiest way to check the sensor is to plug a PID reader into the OBD-II port to determine the PCM read value.