Hussein's 1998 V70 Xr : The Force Awakens

[JCviggen]

So you can still map the fuel based on boost pressure as if the system were map based? If you can do that then it's not so bad, but if peggiung tha maf at say 18psi means that the ecu adds the same amount of fuel for 18psi as it does for 22psi then that friggin useless.

Why? Do you want to run different boost every 5 minutes? IMO people tend to stick with 1 boost level. Want to turn it down? It takes 5 seconds to flash in another map (even while driving)

You can make maps for every single boost level you ever want to use.

I'd be scared as hell to run a 4.3/4.4 tune with advanced timing up top. If the knock 'noise' is lost for some reason, then say bye-bye to that engine.

The ECU stops listening for knock somewhere above 5K rpm. Because it can't tell what's knock and what is not it will ignore the knock sensors. Thats why people are able to melt pistons easily if the tune is off. Always at high revs.

I dont think the maf diameter per se is the limiting factor here, just the stock maf mass flow limit.

Im sure newer maf units have a higher mass flow limit, using the same ID as the stock 850/x70 units.

Yes but it doesn't really matter, the 4.X ECU cannot register "more" flow. And IMO in practice it doesnt really matter. I do not think my car would run any better if it could see more airflow.

Though even if you move up to a 3" MAF housing, that's only a 20% increase in flow area.. so if Hussein's limit of 231 g/s is the actual limit for all M4.4 ECUs, that only brings us up to ~280 g/s, which still isn't enough to give satisfactory flow headroom.

I know Jan will read this as some point. Jan, on your setup, have you kept track of how much air flow the ECU reports going through the MAF? I know you've said that you don't hit 100% load, and you're closer to 50% by the time the rev limit rolls around, which implies that there is some other factor at work here that I'm mindlessly overlooking

Going to 3" will add more than 20% flow. I calculated it once but it's around 35% I believe.

I hit 100% load around 5000 but then it drops off again into the high 70s. I'm not sure why it behaves like that. Stock size would stay pegged at 100 all the way through.

[Captain Bondo]

Why? Do you want to run different boost every 5 minutes? IMO people tend to stick with 1 boost level. Want to turn it down? It takes 5 seconds to flash in another map (even while driving)

You can make maps for every single boost level you ever want to use.

Because boost does not transition instantly from 0 to max, and you don't always give the car enough throttle to acheive max boost. In those situations the car will be way rich. Just becuase my wastegate is set at say 20psi does not mean I don't have a lot of times when the car is at 15psi or 18psi, making less hpo and therefore needing less fuel, but the ecu would not be able to tell. The timing will not be anywhere close to optimal either. Timing retard should to change consistently with load.

[turbotuner]

Forgot to say that TT looks like a GREAT tool, it's just the motronic code / hardware limitation that (sort-of) sucks...

I agree. That's why we are developing extra features which will take it way beyond normal motronic capability. So in the near future, users will have all the current advantages of the TT system, plus the option of many features normally associated with standalone systems.

[JCviggen]

Because boost does not transition instantly from 0 to max, and you don't always give the car enough throttle to acheive max boost. In those situations the car will be way rich. Just becuase my wastegate is set at say 20psi does not mean I don't have a lot of times when the car is at 15psi or 18psi, making less hpo and therefore needing less fuel, but the ecu would not be able to tell. The timing will not be anywhere close to optimal either. Timing retard should to change consistently with load.

...which is why you have all those cells in the middle. If you're not going full throttle but still making 15psi for example chances are you will NOT be maxing out the MAF. Boost does not equal air flow, the throttle body (and TPS) is still in there.

If this was such a problem as you make of it every tuned M4.X car would run like crap. They don't, regardless of maxing the maf at WOT and target boost.

[Captain Bondo]

15psi in the intake is 15psi in the intake. It makes zero difference where the throttle is. You are measuring pressure in the intake, after the throttle body.

You can't use the TPS in this case - manifold pressure is what matters. Ugh...

[GeraldJ]

15psi in the intake is 15psi in the intake. It makes zero difference where the throttle is. You are measuring pressure in the intake, after the throttle body.

You can't use the TPS in this case - manifold pressure is what matters. Ugh...

exactly why it would be beneficial to be able to use a manifold absolute pressure sensor and not a mass air flow sensor.

Really how hard would it be to put this into the turbotuner?

[ozzimark]

Really how hard would it be to put this into the turbotuner?

I suspect very difficult, since the basics of how the ECU controls ignition and fuel has changed

Also, from the get-go, my impression is that TT's main super awesome feature is that you can just drop it in without having to make significant changes for it, such as doing custom wiring for a MAP sensor or COP outputs. Doing these things would be awesome, and I'm all for it, but it seems to me that they are outside of the scope of the product. It's also not too far from just moving to a complete standalone system at that point.

Jan, even if you do have all those cells in the middle, if the ECU can't distinguish the difference between 15 and 20 psi in airflow, you end up with a big dead zone in boost where it's gonna run pretty rich if you're not quite at target boost. I was having this discussion with Eric yesterday, and he assured me I was just being too anal about it, and it's a non-issue. To an extent, that is true, because there are plenty of high powered cars out there that run just fine on the motronic system. However, it just strikes me as being a solution that is far less than optimal if you really want to have good control over what the ECU is doing with the engine.

Perhaps there is a way to remove the ECU imposed limit on the MAF sensor signal. That would solve a lot of the problems I am having with airflow measurement :ph34r:

[turbotuner]

exactly why it would be beneficial to be able to use a manifold absolute pressure sensor and not a mass air flow sensor.

Really how hard would it be to put this into the turbotuner?

Since there is a perfectly usable MAF system in place, I really don't understand why the need to change it. It doesn't stop people making big power and it's perfectly fine for tuning. All that is required is for me to implement the means of scaling the MAF so that it doesn't peg for those who need this.

As already mentioned previously, TT will be enhanced so that it does offer the option of significant standalone capabilties. So while there are certain limitations at the moment, in the future these will be addressed while still keeping all the advantages of the basic TT system.

Edited January 29, 2010 by turbotuner

[GeraldJ]

I suspect very difficult, since the basics of how the ECU controls ignition and fuel has changed

Also, from the get-go, my impression is that TT's main super awesome feature is that you can just drop it in without having to make significant changes for it, such as doing custom wiring for a MAP sensor or COP outputs. Doing these things would be awesome, and I'm all for it, but it seems to me that they are outside of the scope of the product. It's also not too far from just moving to a complete standalone system at that point.

I dont see how it would be to difficult to do. both read in 0-5v right?

rumor is that COP is in the future for TT

Since there is a perfectly usable MAF system in place, I really don't understand why the need to change it. It doesn't stop people making big power and it's perfectly fine for tuning. All that is required is for me to implement the means of scaling the MAF so that it doesn't peg for those who need this.

Time to implement

with MAP over MAF the days of metered air and un-metered air are over.

Also makes it easier to adjust fuel trims according to actual boost and not just the air the turbo pulls in.

[Captain Bondo]

here are lots of high powered cars running carbs too. Saying that expecting an EMS to be able to vary fuel and timing with boost is being too anal? Seriously? You cna get nearly the same effect with 5 cold start injectors and just switch them all on at once when you go over 15psi. Add/remove cold start injectors as needed. It's an only slightly less adjustable version of the same thing.

Will it work? Sure. The car will run ok being way rich and way retarded when you have pegged the maf but not yet actually hit the load point you have tuned everything for But the car's power under the curve (and I don;t mean under the rpm curve, I mean under varying manifold pressures) will suck, egt's will be way higher than necessary, and gas mileage will suffer.

I think to replace the maf with a map you'd need to use a maf eliminator kit that also involves a second IAT senssor. It would have to use the IAT and MAP to send out an "equivalent" load signal (the MAP signal would need to be density corrected).

[ozzimark]

I dont see how it would be to difficult to do. both read in 0-5v right?

It's not the electrical wiring that would be the hard part. It's the software in the ECU. Changing tables for fuel and timing maps is one thing. Changing the way the ECU interprets inputs to read those maps is entirely different.

[GeraldJ]

Id be interested to see it. I really dont have a plan to build that much power in my 855 and I am thinking a non-volvo motor in my 242 so its going to a stand alone anyway.

I do plan to get the TT when my built motor comes together anyway. I am just looking at features...

[JCviggen]

15psi in the intake is 15psi in the intake. It makes zero difference where the throttle is. You are measuring pressure in the intake, after the throttle body.

You can't use the TPS in this case - manifold pressure is what matters. Ugh...

You will not hit the same load (or make the same power) at 1/3 throttle and 15psi as WOT and 15psi. And you WILL SEE lower load in the map. I've seen it over and over with maptrace. Bottom line maxing out the MAF is not a problem, not from a power perspective nor for drivability. Its an M4.x "limitation" nothing more nothing less.

You can increase the MAF dia. but it only complicates things as you literally need to redo the entire map. The ECU adds some more fuel on top of the main map at what it considers "full throttle". So running rich while not going all out can be avoided perfectly.

[Captain Bondo]

You are absolutely wrong. 15psi at 1/3 throttle and 15psi at WOT is exactly the same unless you have iITB's. ITB's change port dynamics and VE relative to their position.

How do you think MAP based engines even function? They don't care about throttle position. They only use it for accel/decel enrichment.

If there is 15psi in the intake, the injector duty cycle will be at a certian level. That level wil not change based on TPS. The AFR will be the same.

I could prove it with datalogs except that my MAP based car doesn't even have a TPS, it doesn't actually need it.

How are we even arguing this point? It's as basic as it gets....

[ozzimark]

It would be nice to know how the ECU calculates the engine load... and what it considers to be that "full throttle" tripping point.

You are absolutely wrong. 15psi at 1/3 throttle and 15psi at WOT is exactly the same unless you have iITB's.

I believe he is not stating that 15psi is different at 1/3rd throttle and WOT, but that the ECU interpolates different load cells for the two different conditions.