ThomasGS4

iTrader: (19)

It is definitely possible.

Nope, doesn't take very long. The car has been driving fine today, so I guess I'll see what happens and update this thread if needed. Gentlemen, thank you both for all of the guidance!

mitsuguy

iTrader: (2)

Here ya go

GS4_Fiend

iTrader: (22)

Bad MAF or high fuel pressure would effect both banks don't ya think? Appreciate you posting this up.

mitsuguy

iTrader: (2)

One would think, but as you see in the deal, all of those cars had only the p0172 listed, not a p0175 listed as well...

again, I know how weird it is, but sometimes its just how they are... I'm sure if we were to look deep into the toyota programming, it might be evident why, but that is way too much work...

ThomasGS4

iTrader: (19)

Hate to say it, but the CEL came back today. Same P0172 code.

After reading through this thread, I'm wondering if it is the fuel pump starting to go?

https://www.clublexus.com/forums/gs-...n-problem.html

The car starts hesitating and barely starts after its been driven for a while.

GS4_Fiend

iTrader: (22)

what was the freeze frame data?

ThomasGS4

iTrader: (19)

Well, right after it came on, I pulled into a parking lot and took this data while holding the RPM at 3k:

Coolant Temp: 186 °F

STFT Bank 1: 2.3%
LTFT Bank 1: -33.5%
STFT Bank 2: 0.7%
LTFT Bank 1: -32.7%

mitsuguy

iTrader: (2)

Dang, 33%

I know you tried a different mass air flow, but there are only two real options at this point - the computer is reading too little air or fuel pressure is way too high...

by your scanner, what is your airflow in grams / second? (or any other measurement besides hertz)

need idle and 2500 rpm...

ThomasGS4

iTrader: (19)

At idle (745RPM), it reads 0.6lbs/minute.

At 3k RPM, it reads 3.7lbs/minute.

ThomasGS4

iTrader: (19)

I'm really leaning towards the fuel pump. When I start the car after driving home from work (25 miles), it'll barely start and stay at 200RPM for a quick second, then bounces up to normal. Also, when the car is warm and has been driven for a while, when I initially press on the gas, the RPM will go up, go down a few hundred RPM, then back up.

mitsuguy

iTrader: (2)

nope, not the fuel pump... at least not based on those numbers

your idle lb/min is good, however at 2500 rpm in neutral, should be significantly less than where you are at...

convert to g/s, and you are at 4.5 g/s idle, 28 g/s at 3000 rpm... at 2500 rpm, you should be reading 16 g/s... granted your number at 3000 should be higher than at 2500 rpm which is where Lexus publishes their specs at, but you are way more than where you should be...

GS4_Fiend

iTrader: (22)

That's actually live data, not freeze frame. But base on that data you have given, I doubt it's the MAF sensor. My educated guess is since it's rich on both banks, I would check fuel pressure to see if it's high and make sure the EVAP purge valve is not stuck open. That's all I can offer over the internet. GL man.

ThomasGS4

iTrader: (19)

Wouldn't an EVAP problem throw a P0441 or P0446?

I am only looking at a P0172, which is a bank 1 only code. I will check the fuel pressure today after work and will report back with my findings.

mitsuguy

iTrader: (2)

Did you miss my post...

your mass air flow is not reading properly for the engine speed...

ThomasGS4

iTrader: (19)

My apologies. So the MAF sensor is the issue?