P0171 with Landtank's MAF

[alia176]

I'm missing the association between vacuum leak and knock sensor malfunction code. What's your line of thinking that ties these things together?

Tom,

In my case, code P0171 (lean) is pointing me to a vac leak of some sort. If you look at my screen shot from 1/9/12, the very last picture shows that while I'm idling, I'm pulling in 0.5 lbs/min and my long term trim is 16%. There maybe some air that is unaccounted for is my guess.

Rick, did I say that correctly?

 

[landtank]

Yes. the long explanation is this:

Any air entering the engine after the MAF sensor is unmetered and will not show up in the AFR reading.

This extra air will cause a lean condition because the ECU will not know to add fuel for this air, so it responds to this by increasing the FT% which adds that missing fuel.

However this extra air/fuel will cause the engine's RPMs to increase and the ECU will then adjust the IAC circuit to bring the RPMs down to their target point.

By lowering the RPMs even less air is going through the MAF sensor so the AFR value drops further.

I would think if the AFR value was closer to expected and you had the high FT% it would be fuel related.

But since the AFR is low I'm thinking a vacuum leak and since it's at idle I would also think it's in the intake after the throttle body.

 

[alia176]

Yeah, what he said up above......

 

[fzjconvert]

Good luck I'm glad that I was able to figure out what worked for my truck!


Rick WHERE THE HE++ are the TURBO UPDATES? hijack out

 

[alia176]

More data points - '97 landcruiser

Here are some screen shots from the '97. I took it to work yesterday. Coincidentally, it too is experiencing P325 but that's it. No P171 for this one.

Both 80s have a smooth idle, plenty of power and nothing out of the ordinary fuel economy (both suck).

Let me know what you conclude by looking at the screen shots!

 

[landtank]

The first thing I notice is that the tool you are using only reads tenths of a lb in air flow. That's not accurate enough to really use it the way I was in determining where your PO171 is coming from.

The problem truck reads .6lbs and the good truck reads .7lbs. Since the unit rounds to the closest .1 lb the readings could be .64 and .66 which would be close enough to be the same.

Both trucks have similar FT% while driving so it's likely a fueling issue only during idle on that one truck with the PO171.

So I'd agree with looking at things fuel filter, pump, relay. One of my earlier suggestions was to jump the relay for the pump to run on the high side during idling. If you see the FT% go negative then that would indicate the problem is in the fuel system.

As far as the knock codes, have Mike send you the kit when it's available and just start swapping things out.

 

[alia176]

I'm currently in the process of swapping the knock sensors to see what ends up changing, if any. These brittle harnesses make working on the sensors a challenge to say the least.

Thanks for the evaluation.

 

[TrickyT]

MAF air flow rate is a 2-byte OBD-II value with 0.01 grams/sec resolution. This translates to 0.0013 lbs/min resolution. So the values coming from the ECU are plenty good enough for the measurements needed here. It must be the software that Ali is using that limits the readings to a single digit after the decimal point.

 

[landtank]

you know if you haven't swapped the MAF sensors between the trucks yet you should do that. Get the problem truck up to temp and then swap them over. Watch the idle fuel trims and if they come down significantly than it would indicate an issue with that.

 

[alia176]

I swapped over a different knock sensor #1 this weekend and monitoring for P325 code. So far, it hasn't returned. The original knock sensor #1 and #2 checked out per FSM but still, swapped in a different one for #1.

Looked for vac leaks but didn't find any obvious vac hose issues. I wanted to check the tightness of the intake bolts but they're a PITA to get to with all that junk in the way.

 

[NLXTACY]

Sooooo...

In other news, this CEL came on again. I printed the pages I needed to check MAF sensor first, along with cleaning the sensor, and I just realized the FSM specs are no longer valid since doing this mod. The sensor is not stock, its the 22204-07010 sensor. So I don't have the correct MAF meter resistance and operation specs.

For stock I would be checking ohms across THA and E2 (pins 2&3), and at the temp its at now it should be registering between 2-3 kOhm.

I also can't check the voltage change with airflow because stock is over terminals E3 and VG (wires 1&4) but since the wires were switched I'm now not sure what it should be.

Anyone have these notes written down?

 

[scottryana]

Original OEM
P1 12v
P2 VG
P3 THA
P4 E2
P5 E3

21010/71010
P1 12v
P2 E2G
P3 VG
P4 THA
P5 E2

Can't help with the voltages, I have been asking about them for a while.

 

[NLXTACY]

Original OEM
P1 12v
P2 VG
P3 THA
P4 E2
P5 E3

21010/71010
P1 12v
P2 E2G
P3 VG
P4 THA
P5 E2

Can't help with the voltages, I have been asking about them for a while.

I think here may be some of the issues. I have the 07010 sensor and my pinouts are not the same as your 71010 or the Original. After testing my THA and E2 pins to check ohms are P1 and P2. For I'm getting 1.67k ohms, which for being currently 68deg F, I am out if spec. But that's if I follow the FSM specs for the original sensor. For all I know I could very well be in spec.

So now here's an issue Scott, we have two different sensors and two different pinouts which means one of us has the wiring incorrect when switched over. I'm willing to bet mine is correct since I've had great results using the 07010 sensor. This is worth checking and MAY be an issue leading to what you have been seeing with your dyno tests. Just thinking out loud.

Meanwhile I just adjusted the springs on the connector, cleaned the sensor wire, and checked the intake hose for cracks. Hopefully I'm CEL free.

 

[scottryana]

I am pulling these straight from Land Tanks installation instructions I can email them to you. The pin outs are laid out along with pictures. I am setup exactly as instructed.

Edit: Actually I will just upload it here, encase someone searches it and needs it in the future.

 

[NLXTACY]

I am pulling these straight from Land Tanks installation instructions I can email them to you. The pin outs are laid out along with pictures. I am setup exactly as instructed.

Edit: Actually I will just upload it here, encase someone searches it and needs it in the future.

That's my point. You and I wired according to instructions but we are using different sensors with different part number and different pinouts.

 

[scottryana]

And youre using Gen I, couple of different factors. But I would hope that the 21010, and 71010 have the same pinouts, it implies they do in the instructions, if not, what happens when using the different sensors? Which one is right?

That's my point. You and I wired according to instructions but we are using different sensors with different part number and different pinouts.

 

[NLXTACY]

And youre using Gen I, couple of different factors. But I would hope that the 21010, and 71010 have the same pinouts, it implies they do in the instructions, if not, what happens when using the different sensors? Which one is right?

I'm sporting Gen1 without the sleeve. I'm also not using either the sensor you have nor the stock one. I have sensor 07010.

 

[landtank]

The sensor 22204-07010 was the predecessor to 22204-21010. I assumed that they were compatible but have been told that there might be a difference. It has nothing to do with wiring but how they do there job.

 

[scottryana]

Sorry swapped the 7 and 0. But yes the 07010 and the 21010 show the same pinout in the instructions.

 

[scottryana]

Oh interesting Land Tank did you do your testing with the earlier 07010 or the 21010?