V50 General : Performance issues - illusion or real?

[LizardOfBodom]

Originally Posted by Xariez

Vacuum is looking identical to my readings, and boost was around 0.5 (though I could have pressed it harder). Fuel pressure is reading everything between 291-300KPA.

...

Wait what?
that seems waaaay too low, seen my results?
even on idle its around 400....

[Xariez]

Originally Posted by LizardOfBodom

Wait what?
that seems waaaay too low, seen my results?
even on idle its around 400....

I never actually went through it, just went ahead and (stupidly) assumed it was OK for some reason, as it was more or less stable and not erratic. Will get those values confirmed when I head out tonight. I'm fairly certain it was around 300 according to a OBD2 reader and Torque (Lite) though.

[Welton]

As far as I remember the FPS 'tells' the Fuel Pump what to deliver so if the sensor is reading bad then the fuel delivery is affected.

Mine began with unusual hold-backs in acceleration but I replaced the FPS before it flagged the Engine Light. It was definitely back to good performance once replaced with a new part. This is probably the cheapest place to start and a good bit of maintenance in any case.

Boost-wise it's quite hard to achieve the full 0.7 bar - you'd need WOT up a long incline, even then you'd mostly see 0.5 - 0.6 bar usually with a healthy engine.

Xariez - have you changed fuel type recently? in my view the T5 seems sensitive to fuels. I've recently been running Millers Eco Max Petrol Power with 99RON Fuel and the Millers additive definitely brought back the sharpness and aggressive throttle response (I've driven the car daily for 11 years I know it well).

[LizardOfBodom]

Originally Posted by Welton

...
Boost-wise it's quite hard to achieve the full 0.7 bar - you'd need WOT up a long incline, even then you'd mostly see 0.5 - 0.6 bar usually with a healthy engine.
....

This, plus just a word from me - best way to test WOT is to start at low speed and high gear, somethink like 3rd gear and 60kmh, its easier to observe boost build from low revs and it sustain it for longer.

regarding FPS - sensor being faulty thats one, but fuel pump being faulty may be another. Although in my case it was the opposite (fuel pump was failing and fuel pressure commanded by ECM was much higher than it should have been). but sensor itself would be my first choice ofcourse and much cheaperr to test.

[Xariez]

Originally Posted by Welton

As far as I remember the FPS 'tells' the Fuel Pump what to deliver so if the sensor is reading bad then the fuel delivery is affected.

Mine began with unusual hold-backs in acceleration but I replaced the FPS before it flagged the Engine Light. It was definitely back to good performance once replaced with a new part. This is probably the cheapest place to start and a good bit of maintenance in any case.

Boost-wise it's quite hard to achieve the full 0.7 bar - you'd need WOT up a long incline, even then you'd mostly see 0.5 - 0.6 bar usually with a healthy engine.

Xariez - have you changed fuel type recently? in my view the T5 seems sensitive to fuels. I've recently been running Millers Eco Max Petrol Power with 99RON Fuel and the Millers additive definitely brought back the sharpness and aggressive throttle response (I've driven the car daily for 11 years I know it well).

I haven't changed the fuel type recently per-se, but I have changed it. Here we got 95E and 98E (I believe 95E has 10% ethanol, and 98E is just about as "pure" as it gets?). When I got the car I put 98E in it, then transitioned into 95E when I saw that the car ran on it. Could potentially try switching "back" though.