Derekboro

Hello everyone,
About six months ago I purchased a 2008 TL with 108K miles. Over the last 3 months the check engine light periodically comes on with the codes P0172 and P0175 for a too rich condition in bank 1 and bank 2. I'm only getting about 18 mpg. I've had the Acura dealership look at it and they cannot find anything wrong with the car. I've also had several mechanics take a look and they have told me everything is fine with the care. Since the gas mileage is so terrible i refuse to believe this. I have changed the O2 sensors, the PCV valve, the air filter, and the mechanics have not found any vacuum leaks. Can anyone please provide some feed back as to what my next steps should be to get the bottom of this issue?

Thanks in advance for any advice!

619rcr

what are the fuel trims like when idling and crusing?. what rpm does the fault occur? (check freeze data) no other issues but codes? you're running 91? no aftermarket parts like intake, cats, exh?

Pair of TLs

Throttle body clean?

Derekboro

I was able to get the freeze data today. The check engine light came back on not long after I started driving. Right now the codes are the only problems I'm experiencing. Before I changed the O2 sensors I was experiencing a lack of power when accelerating from a dead stop and hesitation when accelerating. With the new O2 sensors those problems has been alleviated. Other than the codes and the terrible gas mileage the car drives great. Here is the freeze frame data:

Short term fuel trim Bank 1: -20.3
Long term fuel trim Banl1: -17.2
Short term fuel trim Bank 2: -23.4
Long term fuel trim Bank 2: -17.2

Engine RPM: 896 & Vehicle speed was 24 mph

Hopefully this helps you help me! Thanks a lot!

Derekboro

I'm not sure if the throttle body has ever been cleaned but I'll check to see if it needs cleaning. Thanks!

peter6

Doubt it's throttle body. It doesn't have idle control valve so I don't know how dirty it would need to be in order to cause problems.

What oxygen sensors did you use? If both banks are affected I might suspect MAP sensor, but I don't think I ever seen one fail. I think I had one odyssey with those codes and it was fixed by adjusting valves (exhaust was very tight) but that car most likely had over 200k miles.

Another possibility is too high fuel pressure (although pump usually fails by supplying too low pressure), at least 2 bad injectors (unlikely), timing off (did somebody just do timing belt and sold the car? if not it's due!), and nothing else comes to mind right now.

Derekboro

The O2 sensors I used were NTK (Not sure if this is a good brand). I did take a look at the MAP sensor and seemed to be pretty clean. I'm going to clean it anyway since its cheap to do and its one of the rare things I can do myself. I guess I'll look into your other suggestions.
Thanks for your feedback!

csmeance

I wonder if you have some bad fuel injectors which are not spraying properly. Check the values for your MAF and see if they are in range.

SpiderX1016

Just curious, are you able to read MAP Voltage at Hot Idle? If so, what does it read?