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Discussion Starter #1
I get an occasional P0171 code. Using Torque Pro I'm getting MAF cfm from 1.48 cfm (generally low rpm's<2000) to a high of 42.79 cfm at ~4200 rpm's.

Is this normal or does this suck (or blow)?
 

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That is extremely low. I have 2zz but the sensor is the same... Via torque pro at 800rpm warm idle I see no less than 2.2, usually somewhere between 2.2 and 2.6. Peak 8300rpm (and WOT) I usually see around 155-160ish.

Have you cleaned the sensor?

I would presume at idle both engines use a similar amount of air.
On second thought... The 4200rpm you mention... Is that the airflow cruising at that rpm or WOT to it? There is a big difference.
 

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Discussion Starter #3
The sensor is new (90 days); this is a 2ZZ swap. The 4200 is driving around 80 mph, fifth gear (kept the C56), and not part of the snapshot I've included.. The CEL occurred after non-highway driving, normal circumstances, and prior to the warning I was actually driving in an area with speed bumps going 10-30 mph. Thumbnail shows the MAF as 67.78 cfm when the CEL occurred, or as close as possible to the CEL; don't care much for the granularity of Torque Pro. If there's a better app that anyone knows of, I'd appreciate that knowledge being shared.

P0171.jpg
 

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Discussion Starter #4
In addition to the MAF, which is the issue I am trying to isolate, I'm using MWR's manifold but I doubt this is contributing to the MAF issue. I've only got one upstream sensor. I understand that there are different opinions on this. E.g., the upstream sensor should be close to the engine, which should necessitate 4 sensors. The other option of course would be locating the sensors after the pipes join, but I've gotten some opinions that this is too far from the engine. Not sure why MWR designed this manifold like this, but I'm stuck with it for now. Maybe a PPE header a year from now; right now the engine runs fine no misfires, just an occasional lean P0171. Also ignore the red circles as this is an old picture and I was pointing out the rear braces. The O2 wire, and the other wire tucked under the evaporator for whatever purpose (looks), have been cleaned up as well.


KIMG0031.JPG
 

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Wow.. Steve.. You are STILL over thinking this, and looking too closely at the Issue.. Step back..

1) IF you have the MWR Swap Header running a 2ZZ, then you are only reading the Mixture from ONE Cylinder. So your #1 Cylinder ( the one with the O2 Sensor ) is having issues with it's Fuel Injector.. Likely.
2) There is only ONE ENGINE O2 Sensor { Available as an Option } for this engine/ECU Combination. You can not get two or four O2's to run on this engine/ECU, so stop thinking about this. Your Stuck with ONE. If you want more, you must get a different ECU.. Good Luck on that.. Report beck if you find one.
3) For this Engine and ECU Combination to Play Nice with each other, you NEED to have ONE O2 Sensor AFTER THE 4:1 Merge.. I don't care if it's after the Taillight.. it MUST be after the Merge. It will not be 'Too Far Away'.

Put a Bung after the merge, use a 'Post Cat O2 Sensor in so the wires are long enough, and plug it in to the Right Side O2 Sensor Socket.

Cap
 

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Discussion Starter #6
Cap,

I am starting to believe that you want me to move my bunghole. I think this is good advice and I shall proceed.

Seriously, I can't agree more with you. One question though, do you think the ECU is capable of handling this?

Appreciate your response,

Steve
 

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From October 17 - boy are you stubborn.

Sorry to say you have a total cluster situation here with your O2 sensors.

First of all, as noted previously, the 2zz ECU utilizes only one functional primary (upstream) O2 sensor.

Secondly, it is crucially important that the O2 sensor be positioned after the merge collector, so it can sample the entire exhaust gas mix combining all four cylinders. This is how Toyota intended it to function and this is where Toyota places is it on all 2zz engines whether Celica, Corolla, Matrix, or what have you.

In your situation, you have one O2 sensor that is doing absolutely nothing, (you can just remove it and replace it with a bung cover), and the other one is sampling only one cylinder, leaving the other three completely unmonitored. This is a recipe for disaster.

This may or may not be relevant to your most pressing issue which is the P0171. But definitely it is a situation that you should correct asap.
 

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Discussion Starter #9
My original question in this thread was about the Air Flow, i.e., "why the wide range?" If this is a result of the O2 sensor placement then an acknowledgement would have sufficed. As for over analysis, I've been an Analyst for DoD for forty years and you can't spell Analyst without "anal" so I apologize if I appear to be over pedantic. I'm really a nice guy. Just ask me. 🍺
 

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Cap,

I am starting to believe that you want me to move my bunghole. I think this is good advice and I shall proceed.

Seriously, I can't agree more with you. One question though, do you think the ECU is capable of handling this?

Appreciate your response,

Steve
If you only listen to one person on this forum it should be Cap. In Cap I trust and my trust list is VERY short.
 

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Discussion Starter #11
I trust Cap as well. Thing is, when you (meaning "I") invest in something as ambitious as a 2ZZ swap, I want it to work properly. I could have quit after the 3rd 1ZZ, but as Mr. Frankster pointed out, I'm stubborn.
 

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Steve:..

Your MAF reading will be a function of the RPM of the Engine, and the Position of the Throttle.. Its a Function of VE. Volumetric Efficiency. IE, If the Engine is a 1.8 Liter Engine, running at Sea Level, with a Wide Open Throttle, with ZERO Friction and Inertia Losses in the Air Intake System, and a Square Cam Timing, it will Injest 1.8 Liters of Air Every TWO Revolutions of the Engine ( Four Engine Strokes).
The VE Number will change as a function of engine speed, as the Air has Mass, and does not want to Start or Stop Moving in the Cylinders ( It's a Light Weight Freight Train ).. Given we are talking about Wide Open Throttle (WOT) Conditions.
VE for Turbo/Super Engines at WOT is Greater than 1. VE for Naturally Asperated Engines will generally be less than 1 under all conditions. Sometimes Cams and Tuned Exhaust can Get you Over 1 but not at ALL RPM Ranges.
As the VE is Reduced, Correspondingly the MAF Reading will be Lower. So MAF Reading/RPM will be ~ VE.

VE is Directly related to Engine Load. If the VE is approaching 1, the Engine is Fully Loaded, and consuming the Max Air and Fuel as Possible. Right off of Idle, Full Throttle, you will get close to a VE of 1, with the VE Falling off as the Engine RPM starts Climbing, and the Air does not move as well.
Engine Designers will Generally make the Cam Profile, so the Intake and Exhaust Valves do not Open At Top or Bottom Dead Center.. If they Did, the Engine would only have a Good VE at Idle Speeds. By Offsetting the Valve Opening and Closing by ~20 Deg ( Open and Close LATE by 20 DEG ) the piston is starting to Come Down on the Intake Stroke, then the Intake will open, as not much happens during the Top Dead Center ( TDC ) of the Stroke Anyway. Then AFTER Bottom Dead Center (BDC ) the Piston is Still Moving Up, and at Speed, the Air will still be coming in as the Air Has MASS. Shorthy Later the Intake will Close This is a 'Not Square Cam Timing'.. Generally All Engines re not Square Cam Timing. It's used on the Intake and Exhaust Cam Profiles.
VVTi is a Process where the Intake Cam has a'Varriable Offset' from its base Timing by a Actuator, to assist in Ingesting the Max Amount of Air during a Selective RPM range. VVTI not only needs to read engine RPM, it needs to know VE. The VE will tell the VVTi Calculation Routines how dense the Air is in the Intake System, and there fore its MASS, and what position to put the Cam Actuator In for a Given Engine Load/RPM

So now.. You Gotten to this Point on the Reading, going.. Great he is showing off.. Well could be, but here is why.

At a given Engine RPM and Load, the VE will be referenced by the MAF Reading, but the Actual VE at any given RPM can be changed by, Throttle Position, and Cam Position.

The Only way this can be all repeatable is on a DYNO, where you have a Controlled Environment. AND just to make it all the More Frustrating to try and Understand, TWO engines of the SAME MFG will have different Results.. By a little..

Whew.. I need More Tea..

Cap
 

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Discussion Starter #13
Cap,

Thanks for taking the time for a detailed and well-thought response. It'll take a couple of days for me to digest what you've written as a lot of the automotive lexicon is still new to me.

Cheers,

Steve
 

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Discussion Starter #14
Cap,

Is it safe to assume that a VVTLi (i.e. 2ZZ) engine has a VE >1 when cam lift occurs (>6200rpm)?

-Steve
 

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It is impossible for a NA engine to have a VE > 1. You need forced induction to achieve this.

The O2 sensor needs to be moved to after the merge, and you need to pull the injectors and have them tested. Until you have done this, it is just tail chasing activities. 'Analysis Paralysis' if you will.
 

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It is impossible for a NA engine to have a VE > 1. You need forced induction to achieve this.
Not true. The inertia of the air column causes an overshoot in the chamber filling, sometimes called resonant induction.

The electrical analog of resonant induction is called resonant charging, and results in a VE of essentially 2. This is the theoretical limit with negligible resistance, instantaneous switches, and a fluid that compresses isothermally. The real properties of air and valves mean that you get no where near to 2 in an engine. But, you can get more than 1.
 

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Cap,

Is it safe to assume that a VVTLi (i.e. 2ZZ) engine has a VE >1 when cam lift occurs (>6200rpm)?

-Steve
I would guess that the 2ZZ will approach VE=1.. I do not expect a Stock 2ZZ to get VE=1. Now if you do DDPR Intake and a PPE Exhaust you might get close..

With a 'Tuned System', it will only be VERY effective at ONE RPM range.. traditionally ~100 RPM band. Depending on how 'Peeky' the tune is, as to how far the power band will drop on each side of the Peek..

It's difficult to get a 'Driveable' NA Motor that will give a good Torque wide Torque Band, when you start tossing Cams and Long Pipe Exhausts on the Engine.. With a Torbo/Supercharger the Torque Band can be Wider and more Driveable..
 

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I've worked in an engine testing lab, and the best VE we ever saw (for a NA engine) was for a motorcycle engine at it was just over 85%. The VE was measured in 500 RPM 'blocks' so it might have been higher for a tiny band of engine speed within that 500 RPM range, hard to say.

In theory it is possible to get over 100% on a 4 stroke, but in practice it just never happens. 2 stroke is different.
 

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Discussion Starter #19
Given, if I'm running lean I'm getting too much oxygen in the cylinder. What effect will running a hotter spark plug have on the combustion? I figure on trying this before I get real ambitious and move my bunghole, if the spark plug temp question may be a solution.
 
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