Rb25det Consumption

[Jono.c]

Hey Guys, I'm sure it's asked all the time but i'll ask again..

I have an S1 C34 RS4 Auto Stagea. Car was completely stock 170xxx K's, Only thing i added was a Pod filter.

I've replaced the spark plugs due to missfire and checked all piping etc to ensure not leaks.

I've been running it on 95 but i can only seem to get 260KM out of a full tank.. Usually a mixture or shorter trips and highway drive.

I'm not too hard on it, usually had OD on on highways etc, give it the odd squirt from the lights every now and then..

Can anyone suggest anything i should check or change to try and increase this? I plan to refit factory airbox and run on 98..



Also ever since i got the car it virtually always seems to be on boost.. If sitting on 50k or 90k even with OD on, slightest feather of throttle and its on boost straight away.. Or holding steady at 100k with OD its sitting on boost... Any ideas? I'm not sure what else to check..

Any advice would be great! Cheers

[Jordy32]

Start by putting the airbox back on with a fresh filter

Correct plugs? I'd do a fuel system clean, run it on 98 and replace the fuel filter and O2 sensor, that should give you a noticeable increase

[Jono.c]

Yeah correct plugs with 0.8 gap. I've just cleaned out the o2 for now and ill refit tomorrow to see if that helps

I believe it may have a boost leak, Sometimes it never comes on boost at all even with pedal completely to the floor.. It was sitting for 18 months before i had it with little to no maintenance so i'm not sure exactly what to chase

[junkie]

My bro's Stag always seems to be on boost too, one of the very first things I've noticed once we installed a boost gauge. Need to fully back off the throttle for boost to drop

O2 sensor did help but its still thirsty, probably less than 400km per tank. Weight and small capacity engine don't help I spose

[zoomzoom]

Need a proper L/100km measurement first.

For the driving you describe, 13L/100km or slightly less would be normal.

[zoomzoom]

Also it might be running the low octane map with 95, meaning less timing and so you'd expect to use more throttle and boost just to get the thing moving.

[niZmO_Man]

Use 98RON

Buy a new O2 sensor, these don't last that long (usually around 50-80 thousand km)

Use L/100km when noting fuel consumption.

[MrStabby]

You can see if the o2 is working with CONSULT, but if you cant get your hands on one of those just assume its dead, replace it, and reset the ECU so the long term fuel trims are re-established. Change one thing at a time and do the consumption calc over 3 tanks so its a bit more accurate (ie sum the liters and kms from three tanks together then do the calc).

Once you've done three tanks with the new o2, try 98 and recalculate over the next 3 tanks.

Dont forget to check the tyre pressure - 2psi over what the placard says is an ok start.

Dont run too thick an oil. 5w-40 or similar should work well.