Landtank MAF surprising scangauge results

[landtank]

I like the idea of URD's MAF calibrator with my MAF but was only considering it for boosted situations. But from TurboCruiser's tests and from what I've read on the web the AFR with my MAF at WOT is a good safe one and used by quite a few people. There is room to lean out WOT for more power but that brings you closer to the danger zone as well.

I did contact them about their MAF calibrator with spark control but they said they didn't have a wiring diagram for the LC. That's on my list to check out once these manifolds are done.

 

[turbocruiser]

The new Perfect Power SMT8 supposedly has MAF tunability installed right in. That might make more sense. I'm still waiting for Christo to get the SMT7 going which has wideband feedback loop for super fine tuning. Can you imagine getting all the tunability of the SMT6 PLUS wideband loop PLUS MAF tunability??? That's the whole picture. Christo, any progress on the 7 yet?

 

[Romer]

Going back through this, Christo has some valid technical questions and conclusions.
Rick has lots of "in use" data and results.
My guess is that if we could work towards the middle, we could improve the design.
It's hard coming up with an idea and making it work, it can only get better when others ask the tough questions and an effort is made to address and resolve them.

 

[dhanney]

I have recently purchased LT MAF and a new sensor but have not installed them yet. My rig is S/C with a Mallory Fuel Pressure Regulator (model 4390) and a fuel pressure gauge in the cab. The regulator is adjustable from 3 - 12 psi but I have never adjusted the pressure. I will volunteer to conduct before and after emissions test and fuel pressure guage changes if anyone feels this would benefit this discussion.

Doug

 

[semlin]

I have recently purchased LT MAF and a new sensor but have not installed them yet. My rig is S/C with a Mallory Fuel Pressure Regulator (model 4390) and a fuel pressure gauge in the cab. The regulator is adjustable from 3 - 12 psi but I have never adjusted the pressure. I will volunteer to conduct before and after emissions test and fuel pressure guage changes if anyone feels this would benefit this discussion.

Doug

is it a dyno emissions test that would allow you to sample nox under load?

 

[dhanney]

is it a dyno emissions test that would allow you to sample nox under load?

Nope, just a typical emissions test.

 

[landtank]

I find it interesting that people so readily except the idea of putting on a piggy back and taking the control of fuel metering away from the ECU and basically eliminating all safeguards that it offers but have issues with my MAF setup that leaves them intact.

The normal route of technology is that designs are built on top of previous ones. This is usually done by identifying the previous one's short comings and then adapting the new design to it. This typically happens through use and evaluation not theoretical skepticism.

And any testing of the system for these purposes should be serviced so as to eliminate any other variables from the equation. This would mean a new front O2 sensor, new ignition parts and clean and balanced injectors. These items will produces errors in AFR and exhaust readings. That way if someone sees an error we have ruled out the more likely suspects.

 

[jamisobe]

I think I understand Slee's concern, now. The idea that at high boost there is positive pressure against the FPR instead of vacuum. This positive pressure gains access to another 15-18% of available fuel rail pressure by pushing instead of what happens at idle where manifold vacuum pulls on the FPR valve (pulling on the FPR valve releases pressure into the fuel return line).

I also understand that testing has shown this to not be a problem. Though a too lean condition has not been observed it is still possible that under high boost it may be desireable, in more extreme situations, to increase fuel rail pressure another 15-18%.

So why not install a cheap little check valve between the fuel rail and the FPR that prevents vacuum from lowering fuel pressure, but allows high manifold pressure to push on the FPR valve to gain access to the remaining 15-18% of fuel rail pressure?

Smart Products | Luer Lock & Miniature Check Valves | Poppet Check Valve

 

[Ian Rogers]

I find it interesting that people so readily except the idea of putting on a piggy back and taking the control of fuel metering away from the ECU and basically eliminating all safeguards that it offers but have issues with my MAF setup that leaves them intact.

The normal route of technology is that designs are built on top of previous ones. This is usually done by identifying the previous one's short comings and then adapting the new design to it. This typically happens through use and evaluation not theoretical skepticism.

And any testing of the system for these purposes should be serviced so as to eliminate any other variables from the equation. This would mean a new front O2 sensor, new ignition parts and clean and balanced injectors. These items will produces errors in AFR and exhaust readings. That way if someone sees an error we have ruled out the more likely suspects.

well by using a piggy back ECU you would be able to leave the FPR hookup. you would then be able to tune the Long term fuel trim back to near 0 so that the stock ECU will still have the ability to enrich and lean out the fuel trims. If the ECU is running at +18% and it need 4 % more fuel, there is nothing the ECU can do. If you change the MAF signal by use of a piggy back you can get the LTFT back to closer to 0% giving the stock ECU the ability to change the fuel trims. There is a reason the Toyota still has the FPR hooked up the vacuum, it make the injectors more efficient over a broader range of fueling needs. You might want to give URD a call and talk to gadget about what you are trying to do, he will be able to explain better than i can. But at the end of the day its your truck not mine. I would not want to be near the limits of the fuel trims, 100 miles from service.

 

[jamisobe]

There is a reason the Toyota still has the FPR hooked up the vacuum, it make the injectors more efficient over a broader range of fueling needs.

Do you have a source for that statement that also might elaborate on what exactly are the fueling needs? For example, if the FSM for 93-94 states that vacuum is used to trigger the FPR into reducing fuel line pressure to compensate for poor air flow at idle?

My point is that neither real world testing nor any documentation that has been shown supports your claim.

 

[sleeoffroad]

Do you have a source for that statement that also might elaborate on what exactly are the fueling needs? For example, if the FSM for 93-94 states that vacuum is used to trigger the FPR into reducing fuel line pressure to compensate for poor air flow at idle?

I have never seen the statement regarding the 93/94 idle situation and the 93/94 uses a completely different air measuring system, so it is irrelevant this discussion. Also, no-one has even mentioned the IAC control and if the status of that was checked at idle to see if that is influenced by the MAF.

Here is what Toyota says about the 93 fuel management system.

As to your idea on the check valve, it won't work since it won't allow the pressure regulator to release the air

 

[jamisobe]

I have never seen the statement regarding the 93/94 idle situation and the 93/94 uses a completely different air measuring system, so it is irrelevant this discussion.

I haven't either, but it has been suggested that it does exist and since we are making assumptions from the other point of view then the assumption that Toyota engineers used a vacuum on the FPR to lean idle for 93-92 is relevant since it establishes the precedent that Toyota engineers have used the technique.

Here is what Toyota says about the 93 fuel management system.

That's fine, but it doesn't mention anything about how fuel rail pressure or the vacuum triggered FPR is used to affect fueling operation. It only says constant pressure is maintained.

As to your idea on the check valve, it won't work since it won't allow the pressure regulator to release the air

What if a T was used between the check valve and the FPR? Then hook up a pressure relief valve to the open branch of the T sufficient (say 2psi maybe) to maintain positive pressure on the FPR if needed under high boost.

 

[sleeoffroad]

That's fine, but it doesn't mention anything about how fuel rail pressure or the vacuum triggered FPR is used to affect fueling operation. It only says constant pressure is maintained.

This is just part of a multipage document. You can get the whole thing on techinfo.toyota.com -

What if a T was used between the check valve and the FPR? Then hook up a pressure relief valve to the open branch of the T sufficient (say 2psi maybe) to maintain positive pressure on the FPR if needed under high boost.

I am sure it can be done, but why not leave it as designed and calibrate the MAF?

All that said, I am pretty much done with this thread. I think I made the points I wanted and it for people to take it and do with it what they want.

Anything more will probably appear (and probably already do) to people like w witch hunt.

 

[jamisobe]

I am sure it can be done, but why not leave it as designed and calibrate the MAF?

Nobody has yet proven that the MAF needs to be calibrated beyond its further state. If it is ever determined that more fuel pressure is needed at high boost then the FPR can be forced to open beyond its standard 80% at a level constant to manifold pressure by using a check valve on the line between the manifold and FPR.

I am not a boost head (yet, maybe someday), but it seems to me that the stock fuel system is capable of handling a fairly high level of boost before the idea of increasing fuel rail pressure beyond 80% needs to be implemented. Going beyond the 100% level of available fuel rail pressure from the OEM set-up will obviously require further modification, but is there anyone participating in this forum who can actually exceed the need for 100%, let alone 80%, of the OEM level of fuel rail pressure?

At this point, it sounds to me that from technical analysis as well as real world testing that most may be able to utilize the LT MAF along with the OEM ECU and minor fuel delivery system modifications (disconnecting the vacuum on the FPR) and be good to go for high levels of quality boost. N/A is a no brainer.

 

[Toyo Boyo]

At this point, it sounds to me that from technical analysis as well as real world testing that most may be able to utilize the LT MAF along with the OEM ECU and minor fuel delivery system modifications and be good to go for high levels of quality boost. N/A is a no brainer.

No one is really even pushing for that. Everyone who is boosting their truck is staying in the sub 10psi range. N/A is whatever your altitude I suppose lol (or atitude???) OK - maybe not everyone but you know what I'm getting at.

There are some who have gone higher boost (and other planning it (Ducati 996 springs to mind!)).

But for us mere mortals - it seems to me that Mr. T engineered in some sweet 'tolerances' for us to play with.

After all, no one is going out trying to make donuts with our trucks - is we?

 

[turbocruiser]

All that said, I am pretty much done with this thread. I think I made the points I wanted and it for people to take it and do with it what they want.

Anything more will probably appear (and probably already do) to people like w witch hunt.

Only to those who don't know you.

I'm still diggin the whole technical content of this thread though and would hate for it to peter out prior to getting some sort of consensus going. That would suck. There are lots and lots of opportunities for answering almost all the questions (it is always gonna be hard to know exactly how the ECU analyzes and adjusts to the signals sent its way - no one to my knowledge has ever hacked successfully the Toyota ECU) asked by several fine folks here ... AND ... there are just as many opportunities for the sum of those answers to be "this mod really works well." I'm completely convinced and completely confident in both those things IF we start working together to answer some simple questions. I'm planning to run whatever runs Christo would want with whatever parameters measured. I can roughly correlate what AFR's the wideband is reading at various times through open loop and WOT. Rick has or can rerun logs of back to back Stock MAF to his MAF at 1000rpm, 1500, 2000, all the way up IIRC. Several folks soon will be running dyno runs anyway for various reasons (rebuilds, addons, etc) and they too can run back to back Stock to LT if they want with all the sniffers sniffing for all the things we want. IIRC Christo's program can analyze alot more than mine in terms of injector cycles and injector durations, and he's able to graphically analyze timing maps. Of course he's also able to hook a hardwired fuel pressure gauge to the fuel rail and see what's happening with vacuum, atmosphere, and boost. It isn't that hard to answer more than what we've answered so far and I'd like to think we've got more mental stamina and scientifically motivated methods than this.

BTW, I was trying to steer some thought with what I asked around post #278.

Just fuel for fire here but what do you suppose would happen with 10psi put directly on the FPR?

There are many major hints within the answer to that one question at idle. Taking it further, what do you suppose happens with a range of let's say 2 to 10psi (ie. turbo) put directly on the FPR, right at all the transitions between closed loop and open loop and roaring towards WOT operation??? To Christo's point, we are leaning the mixture by one of or both more air going through the MAF and the FPR reference being removed. To Rick's point, that's what's so great about it.

 

[landtank]

for what it's worth during my testing, applying 8psi to the FPR there was only a 1.5psi increase. Hardly providing a linear pressure differential that has been suggested earlier.

 

[Ebag333]

All that said, I am pretty much done with this thread. I think I made the points I wanted and it for people to take it and do with it what they want.

Christo, I for one appreciate your comments.

 

[turbocruiser]

for what it's worth during my testing, applying 8psi to the FPR there was only a 1.5psi increase. Hardly providing a linear pressure differential that has been suggested earlier.

exactly my point, keep it coming my man! specifically someone hook up a fuel pressure gauge on the fuel rail and start showing some stats while driving the vehicle.

 

[fzjconvert]

OK, so I am not going to say that I understand all the stuff the detractors are chiming in about. All I know is "Does it work or not?" I have to answer YES it does! I installed Landtanks' MAF and my truck has never run better. It is not forced yet but will be it the future. Anyway, I have not noticed any adverse effects since the install. I have gained about 2mpg around town and that is with me being a little heavy on the skinny pedal since the install. Time will tell but as of now a big thumbs up Landtank keep the innovations coming.

Dave