stronger pump increasing fuel pressure?

[jwvand02]

Originally Posted by Spartarus

I see nobody answered your question yet.

The same injector, on the same pulsewidth*, will flow more fuel as you increase the fuel pressure.

* (the signal that controls how long it is open)

The larger question is a bit more complex though - the question is with a FPR in the circuit will it still have that effect and the answer seems to be yes, but by very very little. Steve's comment really did more to give context for the request I think.

[Crunk81us]

I have discussed with the organisers, the motec does not use the MAF or the o2 sensor. It is purely table based from the tps, rpm and load. I guess this way people have less scope to cheat.. if it had fuel trimming from the o2 you could make changes to the engine and the ecu would compensate.. ?

anyway they arent changing a single thing (other than maybe richening it up a fraction in the higher rpms)

I have about 7 things I am changing, adjusting and playing with on my car that I am hoping to net maybe 5kw. a bloody expensive 5kw when an oft tune would probably net me 15.. sigh.

I believe the differences between the cars is manufacturing tolerances.
Tolerances that the oem ecu would probably adjust for but the motec cannot.

one thing i am looking at is the fuel pump. I want to figure out if the factory tolerances extend to the fuel pump/pressure and whether swapping the fuel pump for another one will change anything. the way I see it if the factory tolerance is say 5% and my pump is at the bottom end of that, a simple swap to another pump would sort that out.

While I am asking questions, does anyone have a link to a PDF on the fuel system? ie where the fuel lines run etc? I have had a look and there is a T piece about 300 from the pump on the pressure side. Why? where does it go?

[justatroll]

Stupid question BUT:

Since the engine runs mostly on DI, and the DI fuel pump is downstream of the electric fuel pump (and has its OWN control loop for duty cycle) - WHY does fuel pressure from the electric FP in any way affect the pressure to the DI system?
(assuming the HP is not soo big that the system is starving overall)

[steve99]

Load in stock ecu is calculated off the maf sensor , but who knows with the motec ecu.

Its posible their using SD speed density, if so they would be using the MAP sensor instead.

But its all guessing

[Crunk81us]

Originally Posted by steve99

Load in stock ecu is calculated off the maf sensor , but who knows with the motec ecu.

Its posible their using SD speed density, if so they would be using the MAP sensor instead.

But its all guessing

i can see the map sensor in the software i have, so i think u might be right

[Crunk81us]

Originally Posted by justatroll

Stupid question BUT:

Since the engine runs mostly on DI, and the DI fuel pump is downstream of the electric fuel pump (and has its OWN control loop for duty cycle) - WHY does fuel pressure from the electric FP in any way affect the pressure to the DI system?
(assuming the HP is not soo big that the system is starving overall)

I am going to hook up temporarily a bosch pump with fpr, wind up the pressure and back to back dyno. I will prove whether it makes an iota difference or not. if it does I will go back to the stock pumps and see if there is manufacturing tolerances.

[steve99]

Originally Posted by nikitopo

I didn't know about this change in MAF sensors. Which year happened? 2015?


EDIT: Is it the discussion in this topic ?http://www.ft86club.com/forums/showthread.php?t=106538

im not sure if their is an actual part number change but working on many cars you occasionally notice some cars run about 10% richer than most, mine is one of them, it appears to be due to maf sensor tolerance. Seems to be most noticable in 2013\2014 cars

[steve99]

Originally Posted by Crunk81us

i can see the map sensor in the software i have, so i think u might be right

http://support.moates.net/theory-speed-density/

[Crunk81us]

Originally Posted by steve99

im not sure if their is an actual part number change but working on many cars you occasionally notice some cars run about 10% richer than most, mine is one of them, it appears to be due to maf sensor tolerance. Seems to be most noticable in 2013\2014 cars

I am way out of my depth here, but i do know for sure that the MAF sensor hasnt physically changed, so there must be something else at play?
could it be compensating for something else? like fuel pressure, engine tolerances, engine differences (cams, valves etc)

[steve99]

Originally Posted by Crunk81us

I am way out of my depth here, but i do know for sure that the MAF sensor hasnt physically changed, so there must be something else at play?
could it be compensating for something else? like fuel pressure, engine tolerances, engine differences (cams, valves etc)

Its possible however the main fueling sensors used by stock ecu are maf and 02 sensors

[Spartarus]

Originally Posted by jwvand02

The larger question is a bit more complex though - the question is with a FPR in the circuit will it still have that effect and the answer seems to be yes, but by very very little. Steve's comment really did more to give context for the request I think.

Yep. I was answering his question out-of-context.

Your question is different entirely.

The stock fuel system is returnless. The internal regulator is set at 4 bar. But the stock pump can make much more pressure than that.

You're not going to overpower the FPR.

Take a look at this. Tests with and without the housing.

If you're allowed to change parts, why not just upsize the injectors?

That will provide an accurately calculable change in AFR...

The part numbers don't match in the tests because the first one is the scion fuel pump housing and the second is the pump itself from Denso, because it's not directly available from Toyota without the housing.

Oh, and the split lines feed the port rails and DI pump inlet separately. That's why there's 2 lies going to the bay of that's what you are asking.

[Crunk81us]

Originally Posted by Spartarus

Yep. I was answering his question out-of-context.

Your question is different entirely.

The stock fuel system is returnless. The internal regulator is set at 4 bar. But the stock pump can make much more pressure than that.

You're not going to overpower the FPR.

Take a look at this. Tests with and without the housing.

If you're allowed to change parts, why not just upsize the injectors?

That will provide an accurately calculable change in AFR...

The part numbers don't match in the tests because the first one is the scion fuel pump housing and the second is the pump itself from Denso, because it's not directly available from Toyota without the housing.

Oh, and the split lines feed the port rails and DI pump inlet separately. That's why there's 2 lies going to the bay of that's what you are asking.

yes that is what i was asking.. no we arent allowed to change parts. I'm just asking questions. I still believe there are guys disadvantaged in power (me).. and guys that have absolute freaks or who might be "interpreting the rules". ((tho I am definitely not pointing any fingers or making ANY accusations))

[nikitopo]

Originally Posted by Crunk81us

I have discussed with the organisers, the motec does not use the MAF or the o2 sensor. It is purely table based from the tps, rpm and load. I guess this way people have less scope to cheat.. if it had fuel trimming from the o2 you could make changes to the engine and the ecu would compensate.. ?

Yes this is correct. The factory ECU makes changes and corrections and can adapt up to a point.

Originally Posted by Crunk81us

anyway they arent changing a single thing (other than maybe richening it up a fraction in the higher rpms)

Yes it is a bit frustrating to have "different" spec cars.

Originally Posted by Crunk81us

I have about 7 things I am changing, adjusting and playing with on my car that I am hoping to net maybe 5kw. a bloody expensive 5kw when an oft tune would probably net me 15.. sigh.

In fact, Motec is a much much better ECU unit. It is focused on racing and not on driving in public roads. I had a discussion once with some profesionals drivers here in Nurburgring and they were telling me that if you want to be serious, then you have to remove factory ECU and install a racing one. Motec or Link are some examples. Factory ECU is good in reading data from MAF, trimming from the o2 sensor, using open and closed loops but all these are non-sense for real racing cars.

Originally Posted by Crunk81us

I believe the differences between the cars is manufacturing tolerances.
Tolerances that the oem ecu would probably adjust for but the motec cannot.

So after all the issue was not with the MAF sensor. We never found such a change. There were actual changes in valves and camshafts, but it looks that the factory ECU can adapt and they didn't change anything else.





Have fun with the races!!

[Crunk81us]

Originally Posted by nikitopo

Yes this is correct. The factory ECU makes changes and corrections and can adapt up to a point.


Yes it is a bit frustrating to have "different" spec cars.



In fact, Motec is a much much better ECU unit. It is focused on racing and not on driving in public roads. I had a discussion once with some profesionals drivers here in Nurburgring and they were telling me that if you want to be serious, then you have to remove factory ECU and install a racing one. Motec or Link are some examples. Factory ECU is good in reading data from MAF, trimming from the o2 sensor, using open and closed loops but all these are non-sense for real racing cars.



So after all the issue was not with the MAF sensor. We never found such a change. There were actual changes in valves and camshafts, but it looks that the factory ECU can adapt and they didn't change anything else.





Have fun with the races!!

Yes I agree the motec is a great ecu. it is however locked so we cant gain any performance from it. the oem ecu actually makes more power.