Hi Folks,

A quick question.

It is not specific to any logging/diagnostics OBD2 platform I do not think. I am using WiFi dongle and iPhone based DashCommand app for live readouts. Rather small and difficult to see I must admit. perhaps iPad will solve this...

Anyhow, What I am on about here is MAP readings I am getting and how theyh compare with what is stated in Fabia vRS 14. twincharger literature.

Ignition on but engine not running MAP - 99kPa (normal atmospheric pressure)

Ignition on and engine running in idle, warm MAP 23 kPa ( 0.77bar vacuum )

Max reading at full load and full throttle at different RPMs MAP 225kPa (2.25 bar). It stabilises at circa 190kPa

The literature states that this engine should be producing between 2.75 - 2.5 bar max boost absolute or 1.75-1.5 bar corrected. So I should be seeing max MAP of 275kPa

Im my head the numbers work out if I assume 23kPa as "zero" and then I am getting the boost levels I am expecting.

Can somebody shed some light on my above musings when spare 5 mins allow plz

Thanks!

EDIT: Another explanationis that it is simply not providing as much boost as it should...

So let me ge this right as is reads a bit mumbly lol

It SHOULD be

Engine off = 99kpa / 14.3 psi (atmospheric) use this as your "Zero"

Engine idle = 3.3psi vacuum

Full load = boost spike to 18psi and settles at 13.2 psi of positive boost above our newly created "zero"

Sounds about right for a tuned petrol car, my tomcat used to produce 200bhp at 7-8 psi but being a 2lt wasn't being squeezed as hard as the 1.4 unit.

Are you not getting these readings?

The actual reading you should as the MAP gives absolute not corrected values are:

full load = 225 kpa settling to 192kpa (approx) this shows the engines producing the correct levels of boost or the MAP is faulty and reading incorrectly.

Edited 20 May, 201313 yr by xpower

Engine idle => 77kPa/0.77bar/11psi vacuum absolute

Max MAP reading => 225kPa/2.25bar/32.6 psi absolute => take away 14.3 psi atm and you get 18.3psi boost corrected spike - that is at high revs and low revs, load dependant

It settles at about 190kPa/1.9bar/27.55psi absolute => 90kPa/0.9bar/13.25psi

Intake temps are around 21C

Car is a factory standard Fabia MK2 vRS on Tesco Momentum99 fuel from new.

1.4 twincharger VAG self-study papers say it should be getting more peak boost at 1.5bar/21.7psi and max 1.75bar/25.3psi when blower and charger are woerking full chat between 2400 and 3500 rpm at full load.

Just to make it clear I cannot feel anything wrong with the car, it pulls like it always did