Not a Newb 171 question.

[Doc2012]

UPDATING THIS THREAD FOR ANYONE THAT CARES:

Turned out to be a clogged injector.

Put them in an ultrasonic cleaner, and no more code.



Conversation at dinner tonight; D= Daughter, M=Me, W=Wife.

D-"Daddy, you have a boo boo on your finger."
M- "I know baby. My truck isn't listening so I had to spank her."
D- "Your truck's a girl?"
M- "Yepp."
D- "Mommy, your car's a girl too."
W- "Yes she is. Her name is Chasity(my ex-wife) because she's broken down and dirty."

After a shitty past couple days, I needed that laugh.


ANYWAY, on to why I'm updating this post.

I have replaced just about EVERYTHING related to this ****ing code. The last thing I replaced today was the injectors, thinking they might be clogged, letting enough fuel by to not harm drivability, but not enough to keep the catalyst happy.

When the code popped back up, I lost it. Kicked stuff across the yard, put a nice dent in the fender, slammed the doors, hood, trunk.

I don't think any of you understand my frustration with this issue at all.

This is the ONE damn thing from getting my truck legal again.

Replaced:
Fuel Pump
Fuel Filter
O2 sensor, multiple times, with multiple known good sensors
Fuel Pressure regulator
Vacuum lines with leaks
Injectors
MAF

Tested:
MAF (before and after replacement)
Injectors (Ohm tested both old and new, checked out. New ones came out of a wrecked Tacoma, that didn't have any CEL on, verified this with my own eyes, Torque Pro and handheld scan tool for pending and active codes. Truck still ran, just frame damage, so the guy was parting it out.)
O2 sensors
Harness for O2 sensors(my brother did this while I was standing there, and said it checked out.)
Engine Coolant Temp Sensor (Ohm tested, again, by my brother while I was standing there, and it apparently checked out.)
Vacuum Leaks, AT LEAST 6 times with smoke tests.
Ran SeaFoam through the PCV 3 times to ensure no exhaust leaks.
PMC valve (Next to evap canister) tested to spec, by blowing air into it, as well as applying power to the valve.


I have no idea where to go from here. My next step is, I guess, to test the wiring at the ECU; and plug each and every vacuum line up and see if it changes anything.

Before I do that, I want to make sure that I'm reading the diagram right.

On this page of the wiring diagram, I have circled the wire I'm going to test in red.

That means pin 4 of connector B, which would be Pin 4 of E10, right? And the one next to it is pin 12 of E10?

I'm really at my wits end here guys. if ANYONE can help me out with this, I would forever be indebted to you.


_____________________________________________________BREAK___________________________________________________________________________

I've done just about everything I can think of.

-Tested the MAF per the FSM, checks out.
-Swapped the MAF.
-Changed O2 sensors, as well as tested O2 sensors per FSM.
-Checked injectors, check out.
-Changed Plugs.
-Changed Fuel Filter.
-Checked Wire and Coil resistance, all good.
-Tested ECT sensor (on front of engine), checks out.
-Quadruple checked for vacuum leaks.

I have no drivability Sx. No prolonged starts, no sputtering, nothing. Even at WOT, the she gets up and goes, as much as she can with 35s.

Here is some raw data from my Torque Pro app. Hopefully this can shed some light on something I'm missing.


Coolant: 127.4F
MAF: 7.9g/s
RPM: 1305.0
Load: 17.6%
STFT1: -20.3%
Intake: 60.8F
Timing advance: 11.5 degrees
Throttle: 9.8%
MPG: 0.0
Boost: -12.1psi
F/T 1x1: -20.3%
O2 1x1: .9V
O2 1x2: .1V
LTFT1: 39.8%

I've got the Fuel Flow rate at the house, but forgot to grab it this morning when I left.

Any help in this would be greatly appreciated.

 

[cbr900boy]

I've done just about everything I can think of.

-Tested the MAF per the FSM, checks out.
-Swapped the MAF.
-Changed O2 sensors, as well as tested O2 sensors per FSM.
-Checked injectors, check out.
-Changed Plugs.
-Changed Fuel Filter.
-Checked Wire and Coil resistance, all good.
-Tested ECT sensor (on front of engine), checks out.
-Quadruple checked for vacuum leaks.

I have no drivability Sx. No prolonged starts, no sputtering, nothing. Even at WOT, the she gets up and goes, as much as she can with 35s.

Here is some raw data from my Torque Pro app. Hopefully this can shed some light on something I'm missing.


Coolant: 127.4F
MAF: 7.9g/s
RPM: 1305.0
Load: 17.6%
STFT1: -20.3%
Intake: 60.8F
Timing advance: 11.5 degrees
Throttle: 9.8%
MPG: 0.0
Boost: -12.1psi
F/T 1x1: -20.3%
O2 1x1: .9V
O2 1x2: .1V
LTFT1: 39.8%

I've got the Fuel Flow rate at the house, but forgot to grab it this morning when I left.

Any help in this would be greatly appreciated.

I know you checked for vacuum leaks but did you check for leaks after the MAF sensor? Somewhere on the intake? Wouldn't unmetered air also cause a lean condition? Wow your STFT and LTFT are at both ends of the spectrum. I'm dealing with an stalling issue so I'm constantly checking my Torque App.

 

[Doc2012]

I know you checked for vacuum leaks but did you check for leaks after the MAF sensor? Somewhere on the intake? Wouldn't unmetered air also cause a lean condition? Wow your STFT and LTFT are at both ends of the spectrum. I'm dealing with an stalling issue so I'm constantly checking my Torque App.

Checked for leaks everywhere.

None that I could find.

 

[cbr900boy]

Checked for leaks everywhere.

None that I could find.

I was going to suggest the usual suspects ie fuel pump, EFI and COR relays, FPR, but based on your drive-ability characteristics I think you would notice other symptoms. I just discovered something with the Torque App that stumped me, when I look at my vacuum gauge on the app it sits at a solid 20 in hg. Based on this, I though I didn't have a vacuum leak, then the other day for shit and giggles I pulled a vacuum hose while at idle and it had no affect on the app gauge. So I guess the only way I can check for true vacuum is to hook up a vacuum gauge to the plenum. I ordered this one on Amazon. And follow this guys video.

Sorry I can't provide more at this time, keep us updated if you resolve this issue.

 

[gamefreakgc]

My P0171 had to be resolved with a new MAF. Turns out it was damaged internally but still worked enough to start the engine. I got a used "turbine-style" one for $47 off a V6 Camry, some of them have the same part.

 

[geohil]

Had a similar issue when I had a small leak in my intake manifold gasket. It was small enough that it was fine at idle. Only under load and driving conditions bumpy enough to shift the supercharger around on the gasket did it pop a code.
Had to use the old starting fluid trick to find it and eventually tighten the S/C down.
May not be it - but figured I'd list it as an option.

 

[Doc2012]

I've about had it with this bullshit guys.

Found a small vacuum leak. Fixed it. Ran another smoke test. No leaks to be seen.

Replaced MAF. still have the f**king code.

New information from Torque Pro.

Seems the new MAF had the short and long term fuel trims leveled out, so why am I still getting the code?

And the freeze frame data from when the code popped.

 

[cbr900boy]

Have you checked your EVAP Canister? I know that when the purge valve is stuck open it will let unmetered air into the intake which causes the same condition as a vacuum leak which in turn causes a "lean" condition. It's worth a look.

-Danny

 

[Doc2012]

Have you checked your EVAP Canister? I know that when the purge valve is stuck open it will let unmetered air into the intake which causes the same condition as a vacuum leak which in turn causes a "lean" condition. It's worth a look.



-Danny

Worth a shot. Where is the valve you speak of?

 

[cbr900boy]

Worth a shot. Where is the valve you speak of?

I have a 98 so mine is located in the driver's side engine compartment. The valve itself is mounted on the outskirt of the canister itself. It has a vacuum hose that feeds the intake manifold AFTER the TB plate. If you have a later model 3rd gen then yours unfortunately is located above the spare tire in the rear.

 

[Doc2012]

I have a 98 so mine is located in the driver's side engine compartment. The valve itself is mounted on the outskirt of the canister itself. It has a vacuum hose that feeds the intake manifold AFTER the TB plate. If you have a later model 3rd gen then yours unfortunately is located above the spare tire in the rear.

Mines a 99, and is located in the same spot. Which valve should I be looking at? I have two.

The one in the center, or to the right?

 

[cbr900boy]

Mines a 99, and is located in the same spot. Which valve should I be looking at? I have two.

The one in the center, or to the right?

The one on the right. The top vacuum tube if you follow it goes to the intake manifold.

 

[Doc2012]

Is that a replaceable part?

 

[cbr900boy]

Is that a replaceable part?

Yes, OEM Toyota cost around 90 bucks. Before you buy one, try plugging that line that goes to the intake and see if your Fuel Time goes down. It's a shot. Also, that valve should start ticking when your rig is at normal operating temp.

 

[GHARP57]

If you need it Doc Ill sell it to you for 10% over cost

 

[cbr900boy]

I was paranoid about vacuum leaks because my rig is old and has a ton of miles so I got this vacuum hose kit and replaced every vacuum hose under the hood. Silicone hoses are far superior to rubber ones.
Check out this thread.

 

[Doc2012]

Yes, OEM Toyota cost around 90 bucks. Before you buy one, try plugging that line that goes to the intake and see if your Fuel Time goes down. It's a shot. Also, that valve should start ticking when your rig is at normal operating temp.

Tested it per the FSM, plugged the line, still the code.

 

[cbr900boy]

Tested it per the FSM, plugged the line, still the code.

Damn. Well the only way to be absolutely eliminate a vacuum leak is use a vacuum gauge and hook it up like the guy in the video. I posted it earlier, if your at around 20 hg/in at idle then you can eliminate a vacuum leak and move on to the next. The vacuum / boot gauge on the Torque App does NOT detect leaks.
FYI, anything above a 12% fuel trim will set off a CEL I believe. At idle I'm at 6.2% LTFT and around 4.0% under load.

 

[Doc2012]

Updated Post 1 with more information.

 

[Yoder68]

How do your fuel trims vary at different rpms? I've been told that a lot can be inferred (by experts, not necessarily by me) from that info.