Malpassi fuel reg

[Guest KILLER-T]

I had a Malpassi fuel reg fitted about 2 months ago because my injectors were getting up to 90% and i was told the new reg would help them out a bit but i noticed at the drags the other night they were getting up to 95% :confused: Does this mean it needs to be adjusted or something. It cant be the fuel pump because that was only put in about 7 months ago any ideas anyone

[BOOSTMEISTER]

Sounds like the fuel reg IS increasign pressure and thus your injectors are pumping harder, this should increase the duty cycle of the injectors. Personally I don't go for adjustable regs, you really don't need it, just get a big pump and all will be good. I have seen so many people with Malpassi regs remove them and just fit a bigger pump. If you absolutely must have a RR Reg then go for the Bosch one it is much more tunable.

[macka]

Ok Dont mean to cut in Boostmeister i think in his case he needs to tweak the fuel reg up a bit.

What boost u running now killer? comon tell me u bastard

[Guest KILLER-T]

Im running 18psi now macka all day every day:burnout: :burnout: and im not to worried about the injectors because it hasnt had a tuneup yet and barrie said it needed a bit of fuel pulled out i got to get off my butt and go down and see barrie its running a bit rich im getting a bit of fuel smoke out the back of the car. What fuel pressure did you have yours set at Macka

[GTS-t VSPEC]

Killer,

I have mine on 40psi, but I only run 1bar, Macka's ended up going to 50psi. If your going to Barrie then get him to adjust it as is required, you don't want too much pressure if it can be helped.

See'ya:burnout:

[SlowGTS-t]

Injector duty cycle at X rpm and X load always remains the same regardsless of fuel pressure as the ECU has no idea how much fuel is going in, just how long to open the injectors for per cycle.

Car will run richer though. You'll need a remap to fix that.

[Guest KILLER-T]

Ok then if load can make my injector duty cycle rise then that must be it i put a new set of tyres last week and they gave me alot more grip and for the first time my car was boosting the way it was set up to

[blind_elk]

Jeez, some ppl talk a load of ****y poo!

'Load' has nothing to do with the stickiness or otherwise of your tyres, Killer.

The 'load' seen by the ECU is basically being measured by the AFM. The ECU has a little table, with 'load' along one side and 'rpm' - which it gets from the CAS - along the other. At each point in the table, there is an 'open the injector' time. So, the ECU gets the load and rpm, and 'looks up' the injector time.

If you change the fuel pressure - by changing the pressure regulator - , then you can change the amount of fuel injected during the duty cycle (injector open time). I've read that its more effective to increase the fuel pressure than to fit larger injectors if you need more fuel for a given duty cycle. Not only do you get more fuel, but it gives a better spray pattern as well.

[turbomad]

KillerT I had a Malpassi along with a fuel press gauge to check on things, one thing I noticed is that from day to day the fuel press seemed to vary, some times at cruise it would just jump up for no reason, I asked around and everyone agreed that they are cheap and not to be used on a car tuned on the edge. Sard or Bosch make good ones but are around $400.

[Guest KILLER-T]

Jeez, some ppl talk a load of ****y poo!'Load' has nothing to do with the stickiness or otherwise of your tyres, Killer.

so how do you explain that every time i have been to the drags its never boosted as much as it should untill i put on a set of real sticky tyres that didnt spinn as much or when the car isnt in gear and rev it there is only a little boost. Now you have confused and my brain hurts please explain

[SlowGTS-t]

"load" = afm signal

so at say 3.8 volts AFM signal and 6000rpm, injector duty will be 95%.

At 40psi fuel pressure this might mean 4L/Min of fuel going into the engine

at 80psi fuel pressure this might be 6.5L/Min

There you have it.To confuse things a bit more ,the AFM signal has a lot to do with how much "Load" is on the car, eg how hard the engine is pulling.

[armbrusb]

Turbomad, do you know which Bosch unit to go for? Do you know a part number?

[Guest INASNT]

just get a 044 fuel pump and pfc with 550cc injectors, then u will be able to control everything.

[Guest Works Auto]

i dont like the mallassi rising rate regulator. Just get an SX adjustable one. there expensive but very good.

[GTS-t VSPEC]

Simon,

Is that the adice you give to customers?

[Sydneykid]

Hi guys, somewhere along the way the message seems to have been confused or is it just me?

If you turn the fuel pressure regulator up, the injector gets more pressure and therefore squirts more fuel during the same opening time. So if your A/F ratios were right before, you will need to reduce the injector opening to get them right after you turn up the fuel pressure.

So just turning up the fuel pressure does nothing for improving the duty cycle. It's the shortening of the injector duration by tuning the ECU that does that.

As for Malpassi fuel pressure regulators, we have found them to be temperature sensitive ie; they drift when they get too hot. So what we do is put them behind a heat shield. In between the brake master cylinder and the inner guard is a good spot.

As the temperature gets colder (winter is on the way) the air is denser and the AFM senses this and the ECU adds more fuel to keep the A/F ratios right. So it is normal in winter to have higher injector duty cycles.

Now KILLER-T has a point, the more resistance (load) an engine has against it the more fuel and air it needs to hold that rpm. More fuel and air means more exhaust and that means more boost. That's why you can't get much boost by free revving. So there must be a point somewhere where the load is just sufficient to make max boost. But if the load is less than that, then less than max boost can be achieved.

Hope that adds to the discussion

[Guest KILLER-T]

Thanx for explaining that for us Sydneykid its exactly what im on about

[Guest KILLER-T]

Originally posted by Works Auto

i dont like the mallassi rising rate regulator. Just get an SX adjustable one. there expensive but very good.

:bahaha: :bahaha: This is comming from the guy that sold me the malpassi in the first place:bahaha: :bahaha:

[Ahh32]

The Malapassi Fuel pres. reg. are heat sensitive and will vary pressures will the regulater itself gets hot. I fitted mine as far away from the engine as possible, and only get very slight pres. variations on hot days when driven hard.

[R32-GTS]

Simon here. What i meant adam was that i would rather have a set pressure and use bigger injectors to have enough flow instead of using a rising rater regulator like a malpassi to squeeze the injectors harder. I wasnt saying its a bad product just that because you have rx7 injectors now you dont really need a malpassi at all. It will probably make matters worse by running the car even richer as those injectors a quite big.

Understand ??