P0171 with Landtank's MAF

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

I will see what I can get with a wideband, should be pretty definitive, but even if it isn't actually running lean, and is correcting with LTFT's, it could show good in the exhaust. Joey also overbored his throttle body, so who knows that could also be contributing. But it does seem like a lot of cleaning, even the much older stock sensor didn't need to be cleaned as often and please correct me if I am wrong, but isn't the majority of your driving city driving? Are you using a stock air cleaner or an oiled K&N?
 
landtank said:
It has nothing to do with how much oxygen is in the stream. You simply don't know what you are talking about.
Click to expand...

Let me get this straight. You say that code P0171 has nothing to do with how much O2 is in he exhaust stream?

So what is the O2 sensor reading that is the feedback for this circuit? On newer trucks A/F ratio sensors are used but an O2 sensor reads the O2 in the exhaust stream.

Again from techinfo.toyota.com

"In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a Heated Oxygen (HO2) sensor is used.

The HO2 sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low)."
 
I just hope and pray that I never get a P0171.
 
Just to understand the jist of all the threads on this thing so far, is the fuel pressure reg still manipulated to fix an issue with the MAF when its put on ?

And the cheap ebay sensor mentioned, [cheap price or cheap knock off?] is it a Toyota sensor, or some knock off?


I have only seen the CEL when it is actually lean in the exhaust, from leak or otherwise, as I have yet to see a ECU with an inbuilt crystal ball, to know whats about to happen.
 
I have a Gen 1 housing that had the sleeve. Did not do well with the sleeve and after reading these newer MAF threads pulled the sleeve out. Within the first hundred miles got a P0402 code. Most likely not related at all since I have no EGR system and am running the resistor where the sensor should be. After a couple hundred miles I got a P0170 code. Never had seen that one before. I'm running an Ultra-Gauge for OBD-II monitoring and after re-setting the CEL and a couple more hundred miles, the STFT and LTFT numbers are much lower and my fuel economy went from 12.5 mpg to 14 mpg.

I have no way of data logging but do watch the Ultra-Gauge and I've had LTFT numbers float around from +19.85 down to -8.35 and this is after hundreds of miles of mixed driving with several starts/stops.
 
One of the things to remember is that having the LTFT skewed to one side reduces the margin of error you have.

If it should be 0% but can swing between -30 and +35 you have a 55% range of operation, with balance to both sides. When it is continuously skewed that is reduced and the chances of getting a code is much more when even ambient conditions forces the changes.

Also, the LTFT is a post combustion correction. What I mean with that is that the truck is seeing a air fuel ratio that is lower than what it wants after combustion and keeps adding fuel. So the lean combustion has already happened. It then adds fuel until the fuel ratios are within the given spec, then reduces the fuel again. In the ideal world no fuel would be added or taken away, but if you are continuously having to add more fuel than expected it means the truck is going into lean combustion all the time and adding fuel all the time.
 
Mike,

Sure you have it, but here is the P0170 explanation

P0170

When the air fuel ratio feedback is stable after engine warming
up, the fuel trim is considerably in error on the RICH side or the
LEAN side
(2 trip detection logic)
 
Thanks Christo. It was just a really odd code to see!

So......are folks running the housings with the smaller diameter? Larger diameter "Gen 1"? Leaving the vacuum on the fuel regulator? Is it a "must" to run the newer sensor?
As of now I have the Gen 1without the sleeve and the FPR connected.
 
Yeah my STFT numbers are down from what they were with the sleeve. With the sleeve it was very noticeable that it was on the rich side - strong fuel smell from exhaust, lots of off idle power that dropped off at higher rpms, STFT in double digits.
Now the main consistent behavior I see is when I let off the throttle quickly it will go to open loop & LTFT jumps to +/- 19. Under steady throttle it is right around +/-3.
 
What about under full throttle? In a closed loop situation when the motor is calling for fuel? I am sure the LT MAF Housing would benefit from a lot more testing than I can do, there are just too many variables to make any measurable comparisons except at idle and at WOT. I can give those numbers, and make guesses about what is happening in closed loop, but I really think the end call is going to be up to each individual. If it is using elevated LTFT, while in closed loop, to a certain point that might be fine, but if the atmospheric conditions change fuel type changes, etc, there won't be enough compensation factor left? I guess I will just have to see what the next dyno says on Friday, post those numbers and make my personal decision for my truck.

clownmidget said:
Yeah my STFT numbers are down from what they were with the sleeve. With the sleeve it was very noticeable that it was on the rich side - strong fuel smell from exhaust, lots of off idle power that dropped off at higher rpms, STFT in double digits.
Now the main consistent behavior I see is when I let off the throttle quickly it will go to open loop & LTFT jumps to +/- 19. Under steady throttle it is right around +/-3.
Click to expand...
 
Just offering up my experience since I have the stock MAF, the Gen 1 & the sleeve. Would be nice to have a dyno.
 
What altitude will you be testing at Scott?

And does the dyno have a weather station, so it can factor in the ambient/humidity/intake temps etc ?
 
Yes it does if you go back and look at my dyno posts it lists, temp, pressure, humidity, etc and does the corrections. I will be testing at like 600ft above sea level.


Assassin_Offroad said:
What altitude will you be testing at Scott?

And does the dyno have a weather station, so it can factor in the ambient/humidity/intake temps etc ?
Click to expand...
 
If you have a scan gauge with the X gauge option, you can program it to display both short term and long term fuel trims in real time. I used this to diagnose a lean condition with my vortec swap. It turned out to be a defective intake manifold gasket set whiched caused the ltft to run constantly greater than 25% (adding fuel), which in turn set the CEL.

Is the OP completely certain the engine is vacuum leak free? Maybe a smoke test is in order to check intake track integrity.
 
I got a hold of Joey's housing and sensor and did a eval on them in my truck.

I have an VOM attached to MAF sensor
an OBDII connection through my laptop
and an innovate wide band LM-1 hard mounted to my Y pipe.

Attached are the pics of the mounting

slee busting 05.webp


slee busting 04.webp


slee busting 03.webp
 
You must log in or register to reply here.

Similar threads

Zurbozz
P0171 code help
Replies
4
Views
551
jonheld
jonheld
StaticTorque
P0171 after top end rebuild
Replies
0
Views
330
StaticTorque
StaticTorque
landtank
P0171, hard starting, rough running, not starting at all
Replies
13
Views
2K
landtank
landtank
Outsane
Landtank podcast
Replies
0
Views
410
Outsane
Outsane

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Share this page

Back
Top Bottom