Our feelings about this issue do correlate.

I know this is splitting hairs: MAF signal is never a load signal, and thus can be reliably measured in garage. Yes surely it correlates with the vacuum changes caused via butterfly movement: that is not LOAD-signal but shaking toes -signal.

The toe-in vacuum change in turn is used in increasing/adjusting nozzle gas input = pwr mgmt correlates as rpm will move up or down. When steady rpm - no effect on MAF signal.

The example vehicle 2. doesnt have to be in gear while towing. When its pushing, it has to be... The vehicle is not even necessary but for illustrative purposes for the LOAD-mystery.

Towing is typical method to get a sputtering M/T engine to run: a diesel with vacuum problems may never start with starter, but get it into speed, 3000rpm, and it will function until tank is empty.

 

We are so close but I am frankly ready to give up
and
Perhaps its a language thing here, but you seem to be hell-bent on twisting words to suit a statement you made and to continue to argue a useless point we do agree on without actually making any sensible statements to further your goal of determining the mixture quality on your particualr motor and your own suspected need/want to compensate .

Last time:

1. I agree that the MAF cannot possibly measure load changes directly because as you say there simply is no technical possibility to do that.

2. The MAF can only generate a signal proportional to the air flow going past it.

3. Since any change in horsepower production requirements on the motor (auto in gear, AC, fans, power steering etc etc) involves the ingestion of both more air and fuel, there will be an increase in the flow of air past the MAF. Since there is an increased measured airflow by the MAF, its output signal is directly dependent on the engine's current horsepower output.

4. WRT "MAF signal is never a load signal, and thus can be reliably measured in garage" .................... if you agree with the above you cannot possibly make that statement. Every motor will have a different amount of losses, friction, electrical loads, etc etc all contributing to different amounts of horsepower required to make the ECU maintain idle speed (or indeed also maintain any other speed you care to mention). Those differences in individual motor horsepower requirements to make it idle constantly (or indeed also maintain any other speed you care to mention) results in differing amounts of air entering the motors, and that different amounts of air entering the motor gets measured by the individual engine's MAFs - and those MAF signals is a direct reflection of the individual engine's load requirements. Our differing MAF signal outputs we both posted confirms that and thus you cannot possibly "reliably measure the MAF signal in the garage" - its as simple as that


So I have given you my readings you asked for, so what now? What possible conclusion can you draw from that to try and achieve your goal?

Lets stop arguing semantics now and try and do/say something worth reading.

 

Not true. The 1&2 -example tells the why.

Conclusion is that your/mine signals are linear, similar. They also tell your MAF is working - measurement value also proven by you. (Notable difference in top rpm signal level, maybe its b/cmine is a flash - only seen on video.)

 

True - but at only no engine load .

You cannot from our measurements deduce that at WOT over the whole rev range (which is where you apparently want to supply extra fuel) the motor is either lean or rich.

I will bet you anything you want that if one of the guys playing with after-market ECUs and bigger injectors and eg turbos were to post their findings of the std MAF measurements here at WOT and maximum power (full load), you will see a completely different range of values - all a lot higher than either of our stationary sets of measurements.

Note already Matt's earlier comment to that effect

 

The biiiigger the flow, the higher the signal.

My MAF numbers cant be compared with actual numbers as its tuned, its signal level is maybe 20-25% down. Linearity is in line. Even comparison with stock wont help too much as all units are individuals.

Airflow, thus MAF signal comes directly and only via rpm and throttle angle. Take on my basic diesel example: at 2500rpm flow is always F, one or ten passengers, pulling or pushing.

But. My current real problems is Rabbits on the bckyard: theyre EU property, dont know the jail time fof MAFing air out of em (one sparrow costs 20euros...) plus ticket. Whattodo?

 

Ok I give up.

In plain English tell me what your problem is and what it is you are trying to do?

IMO what you need to do is you need to stick a CO meter in the Max's exhaust while its doing a WOT dyno run and see what your mixture is like as I said way earlier.

Why all this guessing?

 

heh, he's just splitting hairs. MAF signal is never TRULY a load signal, but when car is in gear, driving normally, a higher or lower MAF signal at the same RPM indicates higher or lower load, unless of course something goes amiss in the engine. Like if you were to have an injector fail you'd need more throttle position to maintain the same RPM even without load going up. Or if you run out of gas but are still in gear, and keep your foot on the pedal for whatever reason, then the MAF will still make a signal even though you are just coasting, making 0 power whatsoever. also, to hold a constant 3000rpm in 1st you will have a lower MAF signal than 3000 in OD, despite Granny not having tossed anymore junk in the trunk. But then again, you can consider drivetrain friction, air friction, and tire friction to all be a part of the load. wiking is only calling sprung (well, and unsprung) weight load, not necessarily outside factors.

 

...bells an whistles dismantled:

Why o Why? ...my M/T 1.6D lacking all bells an whistles, w/o any flips or flaps, direct straight pipe into intake valves, no none vacuum related organs - MAF installed just for fun, uphill/downhill, loaded/unloaded ---> always MAF signal stays the same at 2500 rpm ... or 2700rpm ... or 3500 rpm ... or any rpm any gear. Doesnt matter if its pulled by a donkey, pushed by a truck -or- uses its own engine.

When u can explain that, then its possible to continue, otherwise not. MAF is flow -signal, not a LOAD signal. When TB exists, of course this choked flow -signal varies with choking.

 

Come now - are you intentionally trying to be argumentative?

I have been trying all along to get you to agree to this and now you pop up with this discovery?

Once again

"When TB exists, of course this choked flow -signal varies with choking" ................... and that amount of "choking" is a direct function of your foot on the accelerator pedal or the IACV requesting more air flow ................. and because ...............

Oh stuff this.
Enjoy

 

D Question still unanswered.

 

diesels are entirely different in their configuration.... airflow at all times, and fuel is added to make the desired amount of power. so of COURSE the MAF will show the same signal at any RPM regardless of load, because they aren't throttled......

we are talking about gas (petrol, if you must) engines. and we were actually talking about the 3rd gen maxima to be specific. we don't need to know about every possibility under the sun of every type of engine... just the two particular engines we can have in our cars. so on your diesel car, yea a donkey will make the same MAF signal for it regardless of load. but on a 3rd gen maxima, when driving under its own power, no funky crap happening like bad injectors or or a slipped tbelt tooth or anything like that, will show a correlation between MAF signal and load, enough so that you can use it as a reference point. MAF measures load? no. maf indicates load at a given RPM? normally, yes.

 

LVR took this MAF measurement issue as I said its ok to measure that in garage. Then arises this question what is this MAF -signal really indicating. To clear its function, one has to use simple illustrations. Nothing wrong in using illustrations - pls folks try to handle when boxes get holes, crushed and air seeps in... I do err and often, [see above], its no shame for a human to say so. Let only God be the almighty and know everything and all...

No, MAF doesnt give any indication of load on any engine. Only flow. On maxima, this signal is derived (1+2) from two quantities: 1. choked vacuum 'created' by the flap, 2. rpm.

When u fix weld those two 1&2 stationary, donkey pulling, truck pushing, ign on, ign off = MAF signal is always exactly the same - as in the garage.

Maxima maf indicates vacuum at a given RPM? always, yes

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Lets poke another hole in engine design box: it is inherently stupid to use choking TB's, MAF's measuring in any engine type. For the user, it would be best to build the engines to stand the always fully open intakes. Then handle power only via nozzles like diesels. (Just check on the rabbit 1.6D from 80's, its mpg.)

 

but without a TB, wouldn't a gas engine start detonating like mad? that would be like running a super super lean AFR, something like 30 when you aren't using much throttle. diesels HAVE to detonate.... gas engines never should

as for the top part, i already said that under normal circumstances, where the car is fully functional and driving. nothing about welding the TB wide open, nothing about pushing pulling or anything else. i am only talking about normal driving, because that's the only thing that really matters here, because we like to drive our cars, not weld the TB open and let a donkey pull it. and i guess that you are right about MAF indicating vac @ any RPM, because it's inversely proportional. Higher MAF signal means less vacuum at any given rpm.

but the point is, regardless of what the maf actually DOES read, when you don't screw with the car and just drive it, then the maf also indicates changes in load if RPM stays constant and car is in good working order. can you argue with the sentence I just said?

me n lvr were never really talking about the pure function of the MAF, rather, its practical usage. i mean it does no better job of indicating load than the TPS does in the donkey-pull test.

 

To diagnose/troubleshoot MAF, its signal needs to be fundamentally understood. And it can be measured, quantified stationary. Just like FSM says...

Yes, MAF signal can be used in load calculation as one 'tool'. However, the only true load signal can be produced from axle torque measurement device.

Issue is like in rpm gauge: it is NOT a rpm signal, but essentially a small generator and voltage gauge. Normally you dont need to understand this deep, but when you are in trouble, and want to see wassup, its inherently important to see the difference.

My job has been to [suddenly] dig into [new] complex systems and their signals, troubleshoot, write guides how to troubleshoot and adjust things. With complex signals I mean Maxima x1000. THEN, you must rip all the issues into basic elemental pieces just to understand myself. Cant write guides to anyone before u get full meaning for each I/O, process flow, and true meaning for each bit. Yes one can then bypass lots of things calling MAF the load signal [warping the elemental truths] to get things done fast. (Very often you dont need to understand - just do as told, an youre outta trbl...)

So here also was important to understand MAF signal - if u are willing to go deep enough and dig the whole process.

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Yes, gasoline engines wont ever work that way w/o changes. (There are now available also directly into cylinder injecting gasoline engines.) I am not going to the self detonation -or- spark detonation issues, t heres a time restriction. I understand all the basics, but not all things in this world, make errors, me like anybody else... What I want to say is that if diesel mgmt could do with all always open intake, in the 50's then gasoline engine could do the same today with computers. But in whose interests that would be? ...not the 'big oil' and car industry, state tax collectors...

 

that's the main point i was trying to make. and i get how the tach works basically too. when you really get down to it, nothing is what it is. electrons don't care what you're trying to measure. they just do their thing and it's up to us how to control them into what we're looking for.

 

Speed signal can be used defining LOAD. If pedal is pushed and no speed change, then there is [possibly] a hill, engine is being loaded...

Still u can jack front wheels up and troubleshoot MAF or speed signal, stationary.

I know u all know all this, just post-babbling...