Post maf BOV??? And other questions!

[Shehan]

Hey all. This will probably be a noob question, but i would like to learn the mechanics of this and where i am wrong.

So i bought my VR4 a couple of months ago and its been an absolute joy. Now i am also starting to notice things like how much gas i am going through. My galant VRG (which i also still have!) would get me about 700km on a full tank whereas with my VR4 i'd be lucky to get half of that. I've tried driving around in grandma mode, but thats no fun and it also doesnt seem to make much difference.

So my first question is, what are the simple things you have done to improve the fuel efficiency of your car?

Secondly, i want to change my spark plugs. Could someone please give me some details about how to get to the spark plugs in the back of the engine?

Thirdly, i have noticed that one of the previous owners installed a BOV, and it is between the MAF and the engine. Wouldnt this mean that the engine would still inject fuel for air that is vented to the atmosphere through the MAF?wouldnt this cause the engine to run rich for a while when the BOV is activated? Is it practical to place both the MAF and BOV post turbo, but so that the MAF doesnt read air that would otherwise be vented out?

Thank you for taking the time to read! Any advice would be appreciated.

[Davezj]

Any vent to atmosphere BOV will cause the car to over fuel while the BOV releases pressure into the outside world but that is the price you pay to hear the pssshhhhh sound the car is designed to have a recirculating BOV.
The MAF is a delicate bit of kit and would not in pressurise side of the turbo. It is a karman vortex type which relies on very small deflection of a metal foil sheet to reflect light. Every time a small air vortex is created around the plastic parts within the MAF the foil get bent and stops the light from being received by the sensor. These disturbances are converted to a frequency, and is this frequency that is used to calculate the Mass Air Flow (MAF) this is why I believe this type of MAF would not work post turbo. The added pressure and turbulence would destroy the small vortexes.

Apart from the above I don't think the plastic case of the MAF is strong enough to withstand the air pressure it will probably just crack and split open.

[Nick Mann]

Aye, recirc bov is the way forwards rather than maf relocation. It doesn't make much difference to your fuel consumption, the over fuelling is only small and brief. Best instant result for better mpg in my experience is a manual conversion, closely followed by a wideband O2 sensor emulating narrowband for the ecu. They use a lot of fuel - nearly 300 bhp and nineties technology kind of means that you should expect the fuel consumption.

[Shehan]

Thanks guys. While the atmosperic bov sounds nice, i think i'll go back to a recirc instead. Interesting points in regards to the MAF. Does that mean any attemp at cold air induction will also result in a different turbulence than the MAF can handle? I was hoping to relocate the battery, add a heat shield and place a pod where the battery is with a bonnet vent directly above it. I thought about doing that because the stock air intake looks very restricted.

Also, do i have to take the intake manifold out to change the rear spark plugs??

[Nick Mann]

Sorry, double post.

[Nick Mann]

It is widely believed to be the case that pod filters mess up maf readings causing over fuelling.
You can kind of half remove the inlet plenum for the rear plugs, however I completely remove it. There is an article in the members area I think.

[Shehan]

cool. so no pod filters either then?

[SEAN-NZ]

You could get away with it if you have a length of pipe between pod and maf, not sure of required length though

[swinks]

Yes, Sean is right, some length pipe with 90 degree bend will help with induction filters install. I had 90 degree elbow with 15cm legs, 102mm ID, fitted nicely where stock battery is.
IMO, not necessary mod if you not going for a big power and bigger turbos. Gains are next to nothing.