Landtank MAF surprising scangauge results

[nat88toy]

i have no idea what most of this technical mumbo-jumbo is. However, it is a technical thread on a board open for discussion. I say let it continue. If you are not enjoying the discussion or arguments i would just not click on this thread.......

I do hope something constructive comes out of all this. I'm always interested to see facts and fiction on our heavily modified rigs.

i believe this to be more word vomit them technical, never the less its a comical thread at best hopefully some good info will come out of all this

sumo since you so wraped into all this go buy a lt maf and get on a dyno and do some testing already, oh wait you have a 94 so you cant do any testing

 

[concretejungle]

sumo since you so wraped into all this go buy a lt maf and get on a dyno and do some testing already,

I couldn't agree more!

Seriously, Sumo, take a landtank MAF to one of the gurus and analyze the s*** out of it.

 

[SUMOTOY]

luckily for everyone with my MAF installed the ft% are near identical to that of the stock MAF throughout the whole range of operation. No where near 18% at any time.

Be careful, that's a scanguage result that doesn't mean much... Yet. The baseline voltages need to be compared between stock and modded, and you really should be doing this with the FPR hooked up. Which means there is no real data to support your 18% statment (Fuel Injector Pressure Differential is not constant with the modded MAF - See Post 95 in this thread). Technically speaking, you have 18% fuel added LTFT with a STFT of +/-20% to that value. As long as those STFT trend values 'average' 0, the LTFT stays at 18%. Why MAF voltages are a better value.

IME with dyno time, the hour goes by quickly, make the most of it. Looking at this thread, I'd suggest you hook up the FPR, run both voltage slopes, stock and modded. The exhaust gas analyzer on the dyno will give the results, they are what they are. LTFT and STFT are trends that the ecu uses to compensate baseline injector duty cycle. Their 'absolute' value really doesn't mean much, and is not a good indicator of MAF performance. A lot of processing in that ecu takes place after the MAF voltage is tabled.

I couldn't agree more!
Seriously, Sumo, take a landtank MAF to one of the gurus and analyze the s*** out of it.

It's a waste of their time... IMO, all unknowns in this thread revolve around the MAF and the basics to EFI. I could present this thread to my contacts to give a good chuckle (professionally speaking), but the first question would be "Seriously, where's the MAF voltage slopes?" The second I already got, "No FPR manifold reference? Seriously!?"

There's nothing technical to a MAF IMO. All Hot Wire MAF's are simple voltage measuring device. So there's nothing to analyze? There is no relevant data to do so.

Scott J
94 FZJ80 Supercharged

 

[SUMOTOY]

Fuel Pressure Regulators and boost

There seems to be some misunderstanding of how Rising Rate Fuel Pressure Regulators work. Hopefully, this post will help some understand the relationship and the risks of capping a RRFPR during boost. For more on Fuel Pressure Differential see Posts 95-107 in this thread

The 1FEFZ uses a 29lb/hr (310cc/min) injector, rated at 3 bar (44psi - above manifold pressure). This means in a normally aspirated truck under idle vacuum, the 29lb/hr (310cc/min) injector runs at 2.1 Bar to maintain the 3Bar above manifold pressure (Fuel Injector Pressure Differential - per factory FSM and post 95 in this thread).

This also means that under boost with a 1:1 Rising Rate Fuel Pressure Regulator, at 10psi boost pressure, the rail pressure should be 54psi to maintain the 3 bar pressure differential. Let's look at what that means in terms of the 'new' injector flow rates.

At idle (2.1Bar) on a 1FZFE, a 29lb/hr (310cc) injector at 2.1 bar will now flow (sqrt{new pressure/old pressure} * old flow rate = new flow rate) 24.82lbs/hr (260ccmin). That's 15% less fuel than what it flows at 3bar.

Enter the turbo.... If you add 10 psi of boost to the manifold, with a capped FPR, your rail pressure is 3Bar (44psi) but the manifold is .7Bar (10psi) above atmospheric.. So the Pressure Differential is 2.3Bar (33.7psi). So, using the same equation, a 29lb (310cc) injector at 3Bar (44psi) running 2.3Bar (33.7) will now flow 25.96lb/hr (273cc). 10.5% less fuel (lean) with no other changes.

Let's look at the affects of altitude, say 5000feet in Denver with 10psi of boost. Rail Pressure is still 3Bar, but the absolute atmospheric pressure due to altitude is less. So (.8598 x 14.66667) = 12.610 atmospheric = 1Bar *3 = 37.8psi. 37.8psi - 10psi boost pressure = 27.8/12.610 = 2.2PR. The new flow rate is now 25.3 lb/hr (265cc/min) . 15% less fuel (lean).

This indicates that the boosted trucks are at the highest risks with this mod, those boosted trucks at higher altitude, have more risk than those at sea level. However, without a voltage scale of the modified MAF, what's really happening is anyone's guess. With the FPR hooked up, at least you keep the injector flow rates where the software has them tabled for a given manifold pressure.

Summary: A Stock 29lb Injector at 29lbs/hr (310cc) @ 3Bar will flow
24.82lbs/hr (260cc/min) at idle (2.1Bar) - Manifold line connected
25.96lbs/hr (273cc/min) at 10psi boost (2.3Bar) - Manifold line disconnected
25.30lbs/hr (265cc/min) at 10psi boost in Denver (2.2Bar) - Manifold line disconnected

The ECU software sees all these conditions as 29lb/hr injectors installed, since the Fuel Injector Pressure Differential in the software is assumed to be 3Bar always. This means under boost, with the FPR capped, the fuel injectors flow less fuel = lean condition. To accept the theory proposed by Landtank, the installation of a 4Bar Rising Rate Fuel Pressure Regulator would be the 'proper' argument I 'think' he's trying to make. Without the voltage slope of the MAF, it's not relevant to make any argument..... This would also explain why a well respected Toyota Tech at a higher altitude might see higher NOx than one at sea level.


HTH

Scott J
94 FZJ80 Supercharged

 

[SUMOTOY]

Returnless Fuel Pressure Regulation

There appears to be confusion (post 105 and "dyno results thread") on how toyota returnless Fuel Pressure Regulation works. As this doesn't apply to the 80 specifically, I'll breifly describe how it operates.

The returnless FPR on the toyota's is a set pressure contant of 3.5bar (50psi at sea level). Let's use the numbers in my post above to see what happens here. Let's assume for simplicity sake that the 80 with returnless FPR uses a 29lb/hr (310cc) injector rated at 3.5bar.

Under vacuum, the returnless system will maintain 3.5bar in the rail = more fuel is returned within the tank. At 0 vacuum (atmopsheric) it will maintain 3.5bar in the rail = less fuel is returned within the tank. Under boost, the fuel pressure is maintained at 3.5bar = even less fuel returned within the tank. This 3.5Bar fuel rail pressure differential will be a constant under vacuum and boost up to the capacity of the fuel pump/bypass system.

The operation of the returnless is the same 'constant FPR' concept as the rail FPR return type, it's just simpler and produces less EVAP emissions, as only the fuel needed/used is downstream of the in-tank regulator.

HTH

Scott J
94 FZJ80 Supercharged

 

[SUMOTOY]

MAF Voltage vs Load, what happens in the ecu

In post 150 (page 5) Christo speaks to MAF calculations of Load, but IMO, it's more critical to proper engine operation in the 80 than many believe. In a MAF (non-map based) system (toyota 80 included), this is how the tabling works for 'Load' values.

The MAF voltage (actual measured air-in) is tabled against the toyota engineered theoretical ideal (100%) for a given rpm. If the air measured by the MAF is 20lbs of air at 3000rpm, and the 'ideal' tables show 40lbs of air at 3000rpm, the ecu assigns a 50% Load value at 3000rpm. What happens with a larger MAF?

The MAF voltage (actual measured air-in) is tabled against the toyota engineering 1FZFE fixed theoretical ideal (100% = 40lbs air). If the larger MAF now shows 15lbs of air at 3000rpm, and the ideal tables show 40lbs of air at 3000rpm, the ecu now assigns a 38% load value at 3000rpm.... Now what happens?

The OBDII 80 ecu uses those calculated Load Values for shift points (explaining the claims of 'less downshifts'), and more importantly, the OBDI and OBDII 80, uses those Load Values to assign engine timing and AFR deviation values. This explains the 'peppier' feel many have described with the larger MAF, and Christo's high NOx values as well. A lower calculated Load Value uses more timing advance than a higher calcuated Load Value for any given engine rpm. The AFR deviation values will be assigned more 'lean' for any given Load Value as well. This is especially critical during steady state cruising and transitions to higher Load Values.

The good news is, that there appears to ba a switch point within the software that reverts to TPS WOT vs RPM for load (appears to be TPS WOT + ~4000rpm). That said, in the operation of a MAF only system, the accuracy of the MAF to reflect the amount of incoming air is critical to more than just observed WBO2 AFR's.

Christos concerns in post 150 (page 5) seem valid... Accurate MAF in calculating Load Values defines many software derived operation parameters.

For reference confirming how this works in the Toyota, see:
http://www.autoshop101.com/forms/h34.pdf
For MAF vs Load....
http://www.autoshop101.com/forms/h48.pdf
HTH

Scott J
94 FZJ80 Supercharged

 

[aclos3]

Landtank, what percentage of your customer's have reported a damaged or destroyed engine due to a lean condition after installing your device?

I bet if even ONE person had experienced such an issue, there would have been a huge thread about it. I feel very safe running my Landtank MAF, especially seeing that the FI guys seem to run theirs safely. If it does lean out the mix a little, I'd say it has done so well within a safe tolerance. I have enjoyed improvement seen in throttle response, butt dyno acceleration and fuel economy with my MAF.

This thread WAS great. It improved my understanding of the device significantly and some of my previous understandings were corrected by Christo much earlier in the thread. However, people have been running these MAFs for quite a while in a variety of setups and unless there's been a huge cover up going on, damage to our engines is simply not occurring.

We can argue the details and continue this game of technical one-up-manship, but the only real reason for the widespread interest and controversy this topic has created is the potential for DAMAGE to our engines. I have yet to read of damage caused by the Landtank MAF.

 

[SUMOTOY]

....

We can argue the details and continue this game of technical one-up-manship, but the only real reason for the widespread interest and controversy this topic has created is the potential for DAMAGE to our engines. I have yet to read of damage caused by the Landtank MAF.

That has nothing to do with the MAF operation, nor a MAF mod. When we look at 'how' a MAF works within the ECU, we can explain each and every post, argument, and *observation* in the last 15 pages. No motors blew up, but understanding mods should be the rule.

We can opinion it's safe, and go silent about Christo's or others documenting concerns that make it not-so, or we can look at the operation, and the key elements to measuring MAF voltage Load Value, and see that maybe this needs to be looked at in more detail. And possibly LTFT values off OBDII is not a good measurement component of the mod itself.

On a turbo or SC truck running at altitude, the MAF Load Values are critical to closed loop operation, and have very little to do with cumulative 'measured' WB02 values. The Load Values = Timing Values have changed with a MAF mod, period. It could be opinioned that the toyota timing values are quite conservative, and the truck can benefit from massive timing advances vs stock. Without knowing what they are, or what the MAF voltage values are comparatively, 'no one blowing up yet' is hardly a good acid test?

A much more significant correlative approach would be, the MAF voltage values are 'this' stock vs 'this' modded. Load Values and actual timing advance is this 'stock' vs 'this' modded. Possible Conclusion: (in addition to possible WB02 measures) the modded MAF values modded leave enough margin within the fuel and timing parameters to be 'safe'.

What about shift points vs MAF Load Values in the transmission ecu profile? Added risk in a fully loaded trailer scenario?

I have explained how the MAF works in the 80, per the Toyota Technical Information on MAF operation. What many opin 'great' attributes to 'less restriction' with this mod, I believe really show, little to do with the restriction, and everything to do with the MAF voltage slope values. This approach to the same observations, allows explanation of every observed outcome to date, including Christo's.

It appears from my intense read of all relevant threads of this topic, few have proposed any other explanation. And I have not called this mod a 'bad', as there is no data to call it anything but different.

YOMV

Scott J
94 FZJ80 Supercharged

 

[firetruck41]

So, in this thread, one must prove the mod works, by some empirical method, and experience counts for naught. But in the CDL thread (driving w/CDL locked), one must prove your "mod" (CDL all conditions) doesn't work, though only your experience says it is a good "mod". I don't suppose you could see any contradiction here...

 

[landtank]

aclos3, to my knowledge nobody has destroyed an engine. There have been several problems however.

There was one bad sensor that was purchased used
2 issues do to dirty sensors
4 or 5 people had erratic behavior do to week contacts in the harness itself.

Solid information, good or bad, should be posted with out fear of being harassed. It's that free and open exchange of info that has made MUD what it is.

The real issue is that people don't post about these problems because of the Bull s*** that will obviously ensue. Which I have a big problem with.

IMO this amounts to censorship and personally I find the moderators at fault here or at least the site's policy.

Anytime a member of this community gets harassed or expects to be harassed to the point where they would rather not post it needs to be addressed.

I'm not saying people shouldn't be allowed to voice negative opinions. Post your opinion and if need be an additional explanation. But it has been taken to a ridiculous level to here.

 

[SUMOTOY]

aclos3, to my knowledge nobody has destroyed an engine. There have been several problems however
....
I'm not saying people shouldn't be allowed to voice negative opinions. Post your opinion and if need be an additional explanation. But it has been taken to a ridiculous level to here.

With all due respect, I believe Christo was trying to help you understand your own mod. Me, I claim to understand how the 80 ECU works with regard to MAF input, but neither Christo or I (or anyone else) have any data to claim your MAF is more than 'different'.

I claim in my posts above, a larger MAF installed in the 80 works as it does per Toyota's own documentation (and just about any other 0-5v MAF based ecu). If it works differently in your understanding and testing, please clarify my misunderstanding. If Load is a function of fuel and timing, your MAF has also changed the timing values. Period. I see *no* other reference to this in your development thread, and it also explains how a truck can 'feel' better. Is it really? Well, you have more timing advance, and different (lean) AFR addresses under light Load Values. And different shift points. Why? Those are strictly a function of Load = MAF Voltage Values.

I can get into a lot of EFI theory on what those 'ideal' tables the Toyota Engineers use are, and how they are calculated (I have that formula memorized). No interest. However, this thread contains a lot of documentation, and references to 'how' the Toyota ECU works. You can opinion that it works some other way, but your opinion and data has to support the documentation from Toyota, as well as, the results from Christo and others.

I have read intensely almost every post on the MAF mod. With the operation fully explained, it can help you either collect the data relevant to your own project, or understand another explanation of 'how things work' that may be different than your assumptions.

I got cut off from going into detail on MAF here back in June of '07. 150+ MAF meters later, 425posts in this thread alone, and 20 months later, Christo picked it up. 28 months later, I reviewed all posts on the topic, and believe to understand where the confusion and controversy in all the posts is. MAF Voltage Slopes are not the same.

Christo disagrees early on in this thread (and mine back in 07) you have many MAF and Ecu assumptions wrong. I'm looking to get to the basics of the 80 EFI operation - mostly because I continue to have concerns about those with boosted 80's. Please feel free to offer *any* corrections to how I understand the Toyota designed the MAF circuit in the 80 ECU works. And I promise to be the first to congratulate/endorse you on confirming that the LTMAF voltage slope follows the stock MAF.

Otherwise, we all need to understand that changing that voltage slope affects fuel, timing and trans shift points in the OBDII 80 Ecu. For better or worse? I have no idea. No data to support that either way?

Peace

Scott J
94 FZJ80 Supercharged

 

[semlin]

aclos3, to my knowledge nobody has destroyed an engine. There have been several problems however.

There was one bad sensor that was purchased used
2 issues do to dirty sensors
4 or 5 people had erratic behavior do to week contacts in the harness itself.

Solid information, good or bad, should be posted with out fear of being harassed. It's that free and open exchange of info that has made MUD what it is.

The real issue is that people don't post about these problems because of the Bull s*** that will obviously ensue. Which I have a big problem with.

IMO this amounts to censorship and personally I find the moderators at fault here or at least the site's policy.

Anytime a member of this community gets harassed or expects to be harassed to the point where they would rather not post it needs to be addressed.

I'm not saying people shouldn't be allowed to voice negative opinions. Post your opinion and if need be an additional explanation. But it has been taken to a ridiculous level to here.

i agree with landtank in some respects. this whole thread is an exercise in web wheeling / second guessing as bad as anything ever put up in mud. the same speculative points have been made over and over, and none of the speculators have been willing to put up, and now sumotoy won't shut up. if it was up to me i would ban sumotoy. i think he is only posting in here to be an a****** and to provoke rick. that is giving him the benefit of the doubt by the way, because the other explanation is that he is too stupid to realize he is posting the same thing over and over and doing nothing but aggravating a solid mud member who has contributed hundreds of hours to helping others on this site, as well as some great innovation.

but it's not up to me so after i post this i'll suggest it to woody.

i think a debate is healthy and i prefer to stand in here as romer has done and defend rick than censor on this site, because i like to think to think mudders can disagree like men.

 

[Romer]

I said it before and I'll say it again that Sumo is providing zero value in this thread. I let it go because a few felt I should let the slamming happen as it was great dialog. I have been out of town for a week on business not checking much and what I see here today is more of Sumo doing what I said before, instigating when he has no knowledge only his bs theories. Claiming He KNOws, Claiming it's Physics so there can be no disagreement.

Christo provided meaningful test data and everyone including Rick appreciated it. Sumo has provided nothing. For those thinking he is smart and providing great technical info, please search on several on other long drawn out threads with his same MO. Time after time he has wrecked valuable threads with his theories, which aren't accurate, and rarely provides one bit of real test data that he on his own has come up with. he continues to instigate and create swirl.

It's shame because he is a smart guy and has some good technical posts from when he actually has done a mod on his landcruiser and documents what he has done and the results.

Semlin actually said it better

I have my MAF still hooked up in both my 80's and one is supercharged. The supercharged one has the fuel regulator line hooked up and has thrown no codes

 

[tiorio]

Now we're gonna ban people we don't like? Use the ignore user function. Scott may use too many words and cause controversy but he also brought some valid points. He may say them over and over but he also made me go back and re-think this mod and others and how it all works together. IMHO that is the beauty of an OPEN forum. You dont have to agree with everyone, you don't have to read their posts, and you certainly don't have to get all bothered by it unless you choose. My (and the 1st ammendments) $.02

 

[tiorio]

shoot, now I'm guilty of a thread jack! Mods feel free to split this off into OT...

 

[Romer]

Now we're gonna ban people we don't like? Use the ignore user function. Scott may use too many words and cause controversy but he also brought some valid points. He may say them over and over but he also made me go back and re-think this mod and others and how it all works together. IMHO that is the beauty of an OPEN forum. You dont have to agree with everyone, you don't have to read their posts, and you certainly don't have to get all bothered by it unless you choose. My (and the 1st ammendments) $.02

Nothing has been censored

At some point, someones continual barrage gets to be too much. If you came up with a modification and someone continued to express theories on why it was a horrible mod, never provided data, said his points are physics so they cant be argued with and didn't let it go. Even dragging up an old thread when there was nothing new to add just so he could bash your mod., how would you feel about that?

Christo brought data, Sumo could have posted his opinion and let it go. He never does that. He continually continues and drags down threads, not all. In some he does provide value added

I get PMs from people who are afraid to post in a thread after he gets going. I get PMs from people who stop reading the threads because they cant stand what he does.

You should walk a mile in my shoes. How do you be fair to all and shut down what's counterproductive at the same time. Especially when if you really read what he says, he doesn't know what he is talking about. He has been prov en wrong in threads and never agreed, never made the conversation a two way street. This forum is great because of the communication. You cant have communication when one is only on transmit.

BTW - Since this is a private forum, the first amendment does not apply here. This is woodys forum to do with as he sees fit.

 

[T Y L E R]

I get PMs from people who are afraid to post in a thread after he gets going. I get PMs from people who stop reading the threads because they cant stand what he does.

It's pathetic, but I know you're serious Romer. Grow a backbone people and post as you see fit, AND if a guy rubs you the wrong way, or you're tired of listening to some individual then place them on your IGNORE list.


Where is the difficulty in that I wonder


Peace,



TY

 

[landtank]

It's pathetic, but I know you're serious Romer. Grow a backbone people and post as you see fit, AND if a guy rubs you the wrong way, or you're tired of listening to some individual then place them on your IGNORE list.


Where is the difficulty in that I wonder


Peace,



TY

Your right. Next time he's posting something harmful to the truck's mechanics or dangerous to the safety of the passengers I'll just ignore him and pray for those who take his advice.

 

[semlin]

Now we're gonna ban people we don't like? Use the ignore user function. Scott may use too many words and cause controversy but he also brought some valid points. He may say them over and over but he also made me go back and re-think this mod and others and how it all works together. IMHO that is the beauty of an OPEN forum. You dont have to agree with everyone, you don't have to read their posts, and you certainly don't have to get all bothered by it unless you choose. My (and the 1st ammendments) $.02

i was suggesting banning a guy who is deliberately provoking another member who is a solid contributor. take a look at the timing of sumotoy's posts. at one point he bumped this thread 4 times in a row each time days apart trying to get people to post. he has added nothing new.

 

[SUMOTOY]

I would hope that anyone that does a MAF mod, understands what it does. In the case of the 80, the MAF input is the primary determination of *Load* in the software. I defined Load by Toyota's own training manual documentation. Useless? I have seen no references anywhere to the resultant changes in Timing Values with this mod, which is calculated from Load Values.

Anyone can post up what information I posted that is 'wrong' or doesn't interpret the 80 ECU operation correctly. To me, there are no "Suprising LTMAF results". The 15 pages results 'observed' and opined are part and partial to the modification made.

Theory, physics and opinion? I present how the MAF works, in general, and in the 80 ECU. And what a larger/different (uncalibrated) MAF does. Fact: The MAF is only as good as the software that tables it's voltage. What if Christo is right in post 55 page 2?

It sounds like you're hinting that the ECU is not able to take advantage of the better sensor and the gains we're are seeing are from a lean condition that we have created by performing these mods.

I am sorry, but yes, that is my gut feeling.

You have more timing advance from less Load vs tabled software, lean fuel from less Load vs tabled software, and fewer downshifts from less Load vs tabled software.

It sure appears to me that the data presented to date confirms this is (also?) what this mod does. The conclusion that it's 'good' without comparative measures seems premature. This isn't something new, I put this forth over 2 years ago, and Christo agreed back then? Tolerate me as best you can, feel free to attack the MAF operation as Christo, others, and/or I understand it.

Cheers

Scott J
94 FZJ80 Supercharged