Landtank MAF surprising scangauge results (1 Viewer)

[Cattledog]

Nemo, sorry to hear about your problems.

Did you get aftermarket or OEM O2 sensors on the original truck. Many people on the board have had issues with aftermarket O2 sensors. You may want to consider that issue too. In that search you may note that typically when the O2 sensors are replaced with OEM units the truck's mileage downs a bit. The owner ends up annoyed that the truck's MPG drops by about 2 mpg after spending a bit of coin on the sensors...

From the original testing my older O2 sensors tended to cause the truck to run a bit leaner than Rick's truck. This was noted during dataloging. Rick had just changed his O2 sensors and my truck's O2 sensors were original.

Good luck.

 

[Nemo]

Cattledog,
Thanks for the information. I ordered the OEM from CruiserDan as I always do. Nothing but the best

I wasn't even aware there were non-toyota O2 sensors

 

[turbocruiser]

Again I say with complete certainty it was the MAF sensor you got not the MAF housing that caused these problems. Putting in new OEM O2's helps in terms of their accuracy but these problems weren't caused by your old O2's or your new O2's, OEM or not. And again I want to energetically emphasize that I'm not jumping your credibility, just your conclusions. IOW, I'm sure that what you wrote is the gospel truth in terms of the results but concluding it was the MAF housing and not the MAF sensor is like saying a frog without legs won't jump upon command because he's deaf or dumb.

 

[Cattledog]

Cattledog,
Thanks for the information. I ordered the OEM from CruiserDan as I always do. Nothing but the best

I wasn't even aware there were non-toyota O2 sensors

Thanks for the quick info.

It would have been really helpful to have had the truck datalogged and seen the fuel trim data and other sensor data. Your problem seams strange that you had a smooth idle. What rpm was it idling at? Are you running any timing advance over the oem setting? Have you checked for any discoloration on the wire or harness (overheating/broken)? May be worth checking the wire resistance on the O2 sensor's bank one harness to ecu and the MAF sensor to ecu harness. Where you running the 3.0 fan during these issues too? If so why?

 

[sleeoffroad]

Nemo, I would never jump your credibility, and with an honest attempt toward totally serious statements only (per your request and your right) I'll add that I have an aftermarket wideband AF gauge, an aftermarket temperature gauge, have had emissions tests done throughout my time with the LT MAF and I have never had any hot conditions, any lean conditions or any codes anywhere related to the MAF. I have always passed the sniff tests with completely flying colors. I can say with complete certainty that your sensor was bad, not LT's MAF housing. That's All.

turbocruiser, there is no logic in your statement to conclude that the sensor was bad just because you pass a snifffer test. This was a dyno emissions test that is a different thing to what you do in CO Springs.

So how bad was the sensor? Rick stated the sensor gives a rough estimate of the air flow (I do not agree with that, but he chose not to explain his statement). If that is the case, why could the O2 sensor feedback circuit that Rick relies on to keep thing in check, not bring things back to normal? So was the sensor a little bad? Just bad enough to cause issues but still allow the truck to run? He drove with the sensor for a year. The truck ran fine, except for the noted issues that disappeared when the MAF with Sensor was switched.


I would like to ask cruiserdan to see how many MAF sensors he has sold that was bad right out of the box? In our experience I think we replaced 1 MAF sensor in 9 years and that was due to a over oiled K&N filter. I am sorry, I simply do not buy the bad sensor explanation.

 

[cruiserdan]

We sell them often as replacements. I do not recall having a new one bad out of the box but it would not be impossible, especially since the 22204-07010 is a domestically sourced part.

 

[turbocruiser]

turbocruiser, there is no logic in your statement to conclude that the sensor was bad just because you pass a snifffer test. This was a dyno emissions test that is a different thing to what you do in CO Springs.

So how bad was the sensor? Rick stated the sensor gives a rough estimate of the air flow (I do not agree with that, but he chose not to explain his statement). If that is the case, why could the O2 sensor feedback circuit that Rick relies on to keep thing in check, not bring things back to normal? So was the sensor a little bad? Just bad enough to cause issues but still allow the truck to run? He drove with the sensor for a year. The truck ran fine, except for the noted issues that disappeared when the MAF with Sensor was switched.


I would like to ask cruiserdan to see how many MAF sensors he has sold that was bad right out of the box? In our experience I think we replaced 1 MAF sensor in 9 years and that was due to a over oiled K&N filter. I am sorry, I simply do not buy the bad sensor explanation.

Christo, I never stated that this particular person's sensor was bad simply because I passed my emissions test. You are right that there isn't any logic to that, that's not what I wanted to write, and if that is how what I wrote read I retract and apologize about that. My sensor and his sensor are obviously two different things.

I've never seen nemo's sensor, used it, tested it or anything at all except read its results here so I can't really conclude with certainty (as I wrote too prophetically perhaps) that it is this one sensor and only this one sensor (it could be bad wiring, it could be bad hoses, it could be bad fill-in-the-blank ) that caused these problems. But with all other things equal and effective and the fact that the only thing that changed btwn the two rigs running well or not running well was the sensor ... it is a logical assumption that the sensor was at fault. I simply stated that with the many tools I have I have never had any lean condition or any hot condition and that the housing itself isn't to blame here, the sensor in that housing is.

You're saying you don't buy the bad sensor explanation and yet you know that hundreds of rigs with the same housing haven't had any problems like nemo's rig. So I'm saying I don't buy your bad housing explanation. If you are asking Rick to answer "how off" the sensor was, I challenge you to answer "how off" the housing could be.

We all know you love to lash this mod and to lash Rick and that's probably your prerogative (if not a real waste of your time and his time) but please please please don't try to conceal crazy questions to Rick through posts to me. I'm simply saying all other things equal (IOW good wiring, good hoses, good fill-in-the-blank) the sensor is the thing to blame here and I stand strong on that one. Go ahead and try to taunt Rick into answering "how rough" the sensor was or "how rough" the readings were you already know he can't and won't answer those things and that you won't get anywhere with that taunting, but if you gots nothing better to do with your time, have at it. Peace.



Edit: If nemo wants I'll happily send my sensor his way (I have a reason to park the rig for a few weeks anyway) and he can test that one to totally confirm that the housing is at fault.

 

[semlin]

christo, landtank has sold a bunch of these maf combos. nobody else has found they are throwing a po171 code with a truck as soon as they install one. it seems very logical to me to suspect the maf sensor is bad. it sounds like it may be bad in the same way o2 sensors go borderline bad. on one truck it wasn't quite bad enough to throw a code but on the next one it was.

either way, the logical thing to do is swap in a different sensor and see if the symptoms continue.

i also remain interested very interested in the idea of using an exhaust sniffer to test the lt maf and your concern that it might cause trucks to run lean especially at idle. however, nemo's results on that are contradictory. the sniffer said he was running horribly lean, but the two emissions dyno tests said he was running rich.

 

[landtank]

As far as the PO171 code. It's quite possible that the original truck had compensated for the MAF sensor over time. The ECU would only throw a code if the FT% reached 20%. Now installing that sensor onto another system that had a significantly different FT% it would throw the code as it didn't have time to adjust for it.

If someone was installing my MOD and it threw this po171 code immediately upon installation it would indicate to me that the sensor was bad.

I've been in touch with Nemo and once I get the sensor I'll do a complete eval on it and promise to report back.

BTW, Dan has sold these sensors as replacements, they seem to be every bit as fallible as any other sensor and anyone who thinks different has their head up their ass.

 

[landtank]

Nemo, by chance are you running a K&N, TRD or similar oil type air filter?

 

[Romer]

I have had the one in my truck for two years and passed emissions clean with no issues. I have had the one in Sarah's truck for over a year and passed emissions with no issues. I have to pass the same test Nemo does. My only issue was my gas cap needed to be replaced because the seal had worn down. Many in our club also have the MAF installed and I know they have passed the same emissions test Nemo took.

I have had no codes on either truck with the exception of one o2 sensor about 18 months ago which I replaced both of them. They needed it, there was nothing left of the nuts and they could have been the factory ones.

I would still do this mod again on both trucks. I can't answer Christo's concerns and I have tremendous respect for him and his opinions. It would be great to take a truck and do all the tests to answer those questions. I am satisfied with the operation on my own vehicles and others to feel comfortable running this mod and would do it again. Each person must make their own choice as there are a few unanswered questions that Christo brings up. The only way to answer them is to run detailed testing and I am willing to take the risk without those answers.

 

[Nemo]

Let me state again that I know I am different from all the others so far and I am OK with that. I drive the truck like its a sports car. Does that make a difference in what I experience vs someone else, I don't know. It is simply what I have observed. I know the results from the "rolling" dyno tests are different than that of my own Exhaust Analyzer and I have no explanation for that so far but the results are what they are. I wish I would have taken picture because this is the facts.

What I would like to know is how is the sensor going to be tested to determine if it is bad or not. I will try and disclose as much information as possible but knowing now what I have learned I won't be putting the unit back in my truck unless it is for tests.

I would be more than happy to go and source a new sensor and screw it in and perform the same tests for the exhaust gas analyzer but to run it long term to see if the same symtoms come around doesn't appeal to me at this junction.

Truck. 1997 with all the aftermarket mods. 6inch lift, supercharged, new wiring harness (check my previous posts) professionally installed s/c, radiator, thermostat, et al. I guess what I am trying to state is I don't have any problems with my wiring, holes in hoses et al. As of right now I have a 40th which is different that the truck I spoke to as far as the issue I had. I wish I wouldn't have stated that I placed the MAF in my 40th because it appears everyone is focused there. What about my overheating issues, new O2 sensors being fryed in less than a year? That is more the concerns I have vs. what happened to the 40th. I haven't had the 40th long enough to base any observations on overheating or performance problems since it simply hasn't hit the degrees outside to see that yet.

So with all that being said. I would be more than happy to place the "newly purchased" MAF into the 40th and test the truck with and without the MAF to see what condidtions come up with. My problem is if I post them what other statements will come up? I can't seem to get the right focus here to tell me what would you test? And for how long? Do I put it in and "if" I don't throw the PO171 will the results I post be enough for all to see or if it exhibits the same lean results will that be enough? What is it I need to do to show my results.

I am still perplexed to how I determine if the aftermarket MAF is failed? Other than replacing it Rick doesn't have a way to test a failed MAF (looking back through posts) other than to test the voltage from a flow bench?

It is obvious there are numerous folks here that have ran this without issue and that is encouraging but I simply will not rest with this on my truck until I have resolved these issues now.

I am very meticoulous to my trucks performance, reliability, and maintenance so I don't concern myself with trying to find holes in hoses, broken wires, et al. If it is a bad MAF then I am not happy with that answer since I have no way of determining that except replacing it and seeing if things change. None of these issues were observed with the factory MAF whatsoever so purchasing a new MAF sensor and placing it into Ricks housing can be acheived essentially for free since I can return it when I am done testing. Problem is I won't meet any prescribed tests. What are they. Someone care to post that up and I will go as far as I can without taking up all my time.

 

[landtank]

if you send me the sensor I will be comparing it to another sensor in my truck by data logging the event. I can monitor all the sensors through the OBDII port.

I can say with the utmost certainty that no two sensors will respond identical in the same truck and no one sensor will respond identically in two trucks. There is just too many variables but with the things you are seeing if the sensor is the problem it will be obvious.

If you want to do your own thing that's fine but without a baseline to compare it to it will be real difficult.

 

[firetruck41]

Dead thread revival. I'll just get this out up front, I searched for a Landtank MAF thread to tag on to, and have not read this thread in its entirety, though I did peruse it when it was initially started.

I am wondering if there has been anyone who has dyno'd their truck before/after the LT MAF mod? If one were to get it dyno'd on a stock drivetrain, naturally aspirated 96 80 series, what data would be useful? And what would be the best way to do the test? I just found out there is a company that specializes in FI awd imports with a 4wd/awd dyno near me, and it has me thinking...

 

[SUMOTOY]

MAF Comparisons

I revived this thread, because Christo provides some great documentation from Toyota, and follows accepted EFI theory quite well. In my recent discussions with an EFI tuning expert about 80 EFI options, the discussion of the larger MAF installs came up for quite some time. Hopefully his followup will help understand this mod better.

I read this thread completely, especially the OP HP numbers off Scanguage. 70HP sounds not just optimistic, nary impossible. There is concern that a plugged manifold reference port would give no consistent operation around the country or between stock vs force induction motors. Since the fuel injector differential pressure would vary to altitude alone, a guy at 5000 feet would have a different baseline differential pressure than a guy at seal level. All EFI systems assume Fuel Injector Differential Pressure to be a constant.

He followed up on the larger MAF theory that some have presented, and sent me this chart comparing a large flow vs a smaller flow MAF (see attached). With no other changes but MAF, he would expect Christo's observation of high NOx because the larger MAF is going to change the injector duty cycle to be lean during dynamic driving conditions with no other changes (the area between A and B. He also drew in the ECU max input and a random Scamguage (quote sp) limit being possibly higher

He also pointed out where the curves start, both MAF's are good at low flow, and the maximum voltage (~4.85v) vs max flow of the respective MAF is the same. This can wreak havoc on LTFT values, depending on where they are sampling.

His suggestion for normally aspirated trucks is that the reference line be reinstalled, and larger injectors should be fitted (hunt and peck method), or the software be remapped.

Last suggestion, further tests should be on a dyno with an exhaust gas analyzer. He had most unkind words to say about using scanguage for anything more than indicators, especially if there are unknown variables added to the tabling that the scanguage may measure, but the software may not be tabling. As a rule with MAF installs, the resolution is set to scale maximum airflow value of a given engine software (+10% or so) is 4.85v.

I'm not here to knock anything, this is accepted theory of MAF operation. The good news seems to be that other than shorter O2 sensor life, and possible catalytic converter problems, the WOT section of the MAF just dumps fuel. He chuckled when I showed him the 4krpm> charts of AFR. His comment, as soon as that AFR starts down the cliff, it's done controlling anything. Where it 'stops' is incidental.

Scott J
94 FZJ80 Supercharged

 

[SUMOTOY]

MAF Resolution

I have read many posts that a larger/newer MAF has *better* resolution with stock ecu programming. If we look at the above graph reflecting only a larger MAF hardware change, the resolution is actually worse.

The small (B) MAF voltage output from 3v-max will reflect Airflow increase of 150-500lb/hr
Delta 1.5 volts = 350lb/hr Delta measured air

The large (A) MAF voltage output from 3v-mx will reflect airflow increase of 250-1000lb/hr.
Delta 1.5 volts = 750lb/hr Delta measured air

This indicates that the the MAF with better resolution would be the B (stock) MAF, because it has better resolution to smaller changes in airflow - like more than double in the above example. The best method for testing a 'larger' MAF then would be to measure the maximum MAF output voltage at WOT. If you never see it 'peg', you have effectively reduced the resolution of the installed MAF all else being equal (no software changes).

Scott J
94 FZJ80 Supercharged

 

[TrickyT]

This plot (post #375) is an *example* of MAF performance, presumably from the Bosch units whose #'s are listed in the plot. More relevant to the discussion here would be the same plot from an OEM MAF and landtank's MAF where not only has the size changed, but also the sensor technology. This is something Christo proposed doing several pages ago.

 

[semlin]

tom is right. the new unit is both sensor and tunnel. you can't extrapolate anything from comparing two other completely different mafs (for which we do not know the actual sizing).

if landtank's mod resulted in reduced airflow sensitivity, you would expect a rougher idle, vague throttle response, and overall rougher performance. the actual result widely reported is a smoother idle, crisper throttle response and longer delay to open loop. this suggests more accurate fuel management at every stage.

 

[Ebag333]

the actual result widely reported is a smoother idle, crisper throttle response and longer delay to open loop. this suggests more accurate fuel management at every stage.

Suggests, but isn't conclusive in and of itself.

Sumo has the right basic concept, though Slee mentioned it ages ago. Someone needs to go and map out both the OEM and LT setups, then compare. Without hard data, it's all seat-of-the-pants measurements.

 

[SUMOTOY]

This plot (post #375) is an *example* of MAF performance, presumably from the Bosch units whose #'s are listed in the plot. More relevant to the discussion here would be the same plot from an OEM MAF and landtank's MAF where not only has the size changed, but also the sensor technology. This is something Christo proposed doing several pages ago.

Valid testing sure would help, but I didn't restrict the chart variables on purpose. Just assume the bore size is the only variable in the chart in post 375, and it's the same sensor element (see it all the time in new cars). The chart wouldn't change at all. One can propose that 'new' technology does 'something', and it might have a more accurate "A" line, in that the newer sensor voltage might track the A line better (I doubt that, but not relevent really).

That assumption doesn't really change the A line or the B line in terms of pipe diameter effects. If you never reach max output voltage in a given MAF application, it doesn't matter how 'accurate' the new sensor is. By definition it must be much more accurate because (without software changes) a much larger airflow is required to make the same change to the voltage output. But without rescaling the MAF input in the software tabling, it's less accurate also by definition, because the ecu (and/or engine air demand) will never see max voltage. That also means those max voltage MAF input tables will never be accessed > no delta in fuel injector duration.

The actual test that would reflect your proposal would be to compare the same diameter of MAF, using the stock vs 'new' sensor. I suspect very little measured difference doing that. Bore diameter MAF software tabling is called MAF Scaling. The OEM's do it all the time. Without it, you just have chart 375, 'accuracy' is not relevent.

Scott J
94 FZJ80 Supercharged