P0171 and C1201

[Majindan]

Had this truck 3 weeks almost now. Lean code and brake booster codes. Cleaned the throttle body and MAF, replaced the air filter(previous filter was a drop in K&N and it was super nasty looking) and PCV valve a week ago, reset codes, engine light came back on roughly 30-40 miles later. Cleaned the MAF with the proper cleaner using the pressure from the can only, no touching. Cat and 02 sensors were replaced within the last 10k miles, checked vacuum lines visually and with the "spray line connections with carb cleaner" method and nothing. As a last resort, could it still be the MAF? Should I try cleaning it with a pipe cleaner as well as spray?

Also, when I had the intake tubing off, I discovered some oil resting at the bottom of the box between the MAF and throttle body and residual oil inside the plastic tubing and a little on the top of the throttle body itself. I'd never seen this before and curious if there is some weird back pressure going on or something. I'm STUMPED. :ybrick:

edit; I should add that after resetting the codes last night, got in the truck and it ran kind of rough for about 2 mins, and at red light otw to work, the idle was moving between the usual 700, to 600.

 

[JayRolla]

4 thinks can cause this. Bad or failing fuel pump. Bad o2 sendors. Bad MAF. Major vacuum leak. I would guess it's a vacuum leak after what you have done.

Can you monitor fuel trims? It's the best way to diagnose this type of issue.

 

[Majindan]

Whats the best android app to use to monitor this? I have a bluetooth OBDII device and a droid tablet I can use. Any particular lines I should look at that are considered common leak lines or anything? Driving me nuts, thanks for the reply too btw.

edit; this may be irrelevant, but I did replace the off brand gas cap with the correct OEM Toyota one two weeks ago. And just bought Torque app, so disregard app question please, thanks.

 

[JayRolla]

Whats the best android app to use to monitor this? I have a bluetooth OBDII device and a droid tablet I can use. Any particular lines I should look at that are considered common leak lines or anything? Driving me nuts, thanks for the reply too btw.

edit; this may be irrelevant, but I did replace the off brand gas cap with the correct OEM Toyota one two weeks ago. And just bought Torque app, so disregard app question please, thanks.

I use propane and run it around all the vacuum lines. If you hear it rev up than that's the leak. Even better watch fuel trims when using it and if trims change that's where the leak is.

 

[Majindan]

I use propane and run it around all the vacuum lines. If you hear it rev up than that's the leak. Even better watch fuel trims when using it and if trims change that's where the leak is.

I'm at work watching/listening on youtube via "Schrodingers Box", incredibly interesting and full of info. I will be able to monitor STFT/LTFT ratio with RPMs at lunch. Do you know what fuel pressure is supposed to look like at different RPMs by chance?

 

[JayRolla]

I'm at work watching/listening on youtube via "Schrodingers Box", incredibly interesting and full of info. I will be able to monitor STFT/LTFT ratio with RPMs at lunch. Do you know what fuel pressure is supposed to look like at different RPMs by chance?

That's a good question. In boosted applications it raises 1:1 with boost. In an N/a it should hold steady or rise a little. Should never dip.

 

[Majindan]

So, bought Torque, plugged my OBDII bluetooth reader in, shows connected to device, but NO info coming from ECU. Have a very basic wired reader that reads fine and w/e Advance Auto uses works fine as well. Thought maybe it was the OBD reader so I hooked it to my wifes 2016 Kia and it works perfect...wtf? I bought this reader a year ago and it won't work with my 02' Toyota but will with a 16' KIA? What am I missing? Someone please tell me what is going on.