Code P0122, but lacking the usual symptoms

lparsons · May 27, 2021

(I mistyped the code in my original post, it should be P0122, not P1022. The title and the rest of this post has the correct code now)
My 98GT convertible has had the check engine light on since I bought it last summer. I finally put a code reader on it and got P0122, but the symptoms that usually go with P0122 don't match what I'm seeing.
My car is generally idling low, and occasionally stalling out when at very low (parking lot) speeds. It is running rich - you can smell the gas when it's running - but it does not lack power. I can easily spin the wheels in a straight line without flogging it too hard, and it reaches freeway cruising speed without difficulty.
It is definitely not surging, or hesitating.
I haven't checked on the TPS sensor yet - still need to figure out where that is in this car - but I was wondering if there is anything else I should look into first. Should I try to resolve the rich fuel:air mixture (or possible poor combustion?) problem first or could these be related?

lparsons · May 31, 2021

Well that was almost easier to fix than I expected. I swapped the TPS itself - which was about $30 from a local auto parts store - and code P0122 went away. I pulled that off in my garage in about 15 minutes and then cleared the code with my code reader.
However after driving it for a while - notably once I had it on the highway - it threw two new codes at me (they may have been hiding underneath the P0122 and I just didn't see them). Now I have P0174 *and* P0171.
Those codes strike me as interesting as one is bank 1 and the other bank 2, both saying they are running lean. I swapped the MAF sensor in response to this and I'm still seeing the codes. It seems to me that with the codes being the same for the two banks it wouldn't likely be an O2 sensor as those are present on each side (and I wouldn't think it would be very likely to have them go simultaneously on both sides); similarly I'm thinking it probably isn't the fuel injectors for the same reason. I'm thinking I might try the fuel filter next and perhaps the air-fuel ratio sensor (DPFE sensor?) if that doesn't clear it.
The car is still running well - now idling consistently at about 1100 rpm with almost no variance - and making plenty of power but by the smell of it the car is running quite *rich*.
If anyone has any other suggestions please chime in. I'd like to try to resolve this before the coming weekend as we have some nice cruising weather in the forecast

rancorkeeper · Jun 1, 2021

lparsons said:
... making plenty of power but by the smell of it the car is running quite *rich*.
If anyone has any other suggestions please chime in. I'd like to try to resolve this before the coming weekend as we have some nice cruising weather in the forecast

If you're reading lean but running rich, you could have one of these items not working properly:

Intake Air Temperature (IAT)
Engine Coolant Temperature (ECT)
Mass Air Flow Meter (MAF)
Improperly matched/sized MAF and injectors
BAP Sensor

Code P0122, but lacking the usual symptoms

lparsons

lparsons

rancorkeeper

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