P0174 code [solved]

[stokedcrf]

Hi folks

I recently brought over to Canada a MR-S, and so far I'm loving it!
However, the other day it through a P0174 (and only this code).

Bank 2 lean, so I tried a few things to narrow down the issue:

1) cleaned MAF
2) 02 sensors swapped sides (to see if the trouble codes move with it, in an attempt to determine if the sensors are good)
3) PCV valve removed and verified it's working properly as a 1 way valve

For the fun of it, and since I was in working mode I've replaced all plugs, although it was more or less something I do as a new owner and not because of the code.

My google-fu shows that often a P0171 is thrown with P0174's, but in my case, I only have the one code.

Also, when the CEL comes on, the car suffers from rough idle. When warming up or the CEL is off, there's no problems with idle, so the idle seems to be related to the 174.

Hoping someone can point me in the right direction.

THanks!

[Gaz mr-s]

When you swapped the sensors, did the fault switch banks?.  Do you have an obd tester that allows you to see the O2 sensor voltages? - compare bank 1 & 2.  The idle, is it stuttering or fluctuating up & down revs?

[Carolyn]

The PCV valve may seem to be operating but not doing it properly. The poppet inside is spring loaded and the valve's correct operation relies on the spring tension, which degrades over time.

According to Toyota it's a 30,000 mile item. 

Nine times out of ten, that code is down to a tired O2 sensor.

[MRSwede]

Vacuum leak ?

[stokedcrf]

Well! I found out the problem!

After checking all the easy stuff as mentioned in my previous post, it appeared the next logical step was to check the injectors.

I pulled the injectors off, and the "injector insulators" at the bottom were very loose around the injectors. To further that, the cap on one of the injectors were missing, creating for a VERY likely air leak.

I went to the wreckers and picked up a set of 4 injectors complete with seals and insulators from a Toyota Matrix, as a last ditch effort.

BOOM! The car is running INCREDIBLE now, perfectly smooth idle at stop lights, can't even feel it running. The CEL has gone off, P0174 is now gone and never came back.

I swear, the car accelerates sooo much more smoothly now. It sorta seems sluggish or "hesitant" before. It's a LOT more responsive.

I guess being the only MRS I've ever driven, I thought that was normal. Boy was I wrong!

I'm really stoked at the results, it feels like a brand new car now!

Thanks everyone for the tips!