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Atmosheric venting BOV's will make your car chew more fuel, thats for sure, esp with a stock tune :P .

+1

See if you can remove the aftermarket one and just have your stock one.

the smell you are getting out of the exhaust may indicate stuffed cats. both of my cats were blocked when i got my car and it gave off a really bad smell out of the exhaust and were blocking the exhaust flow. changed the cats, smell went away and got a small increase in fuel economy.

i'd also be inspecting all your fuel lines and also the fuel filler neck (they change the insert during compliance and sometimes it leaks). also check your o2 sensor is working correctly, clean your coolant temp sensor and check for any error codes using consult or datascan.

+1

Change your cat to a high flow one.

Also check your fuel injectors to make sure their not leaking. If they are fine, put some fuel injector cleaner in your fuel tank when it hits low then fill it right up. Change your fuel filter and check you spark plugs. I think you mention you have already change it...

u will find dat a o2 sensor makes a huge difference.

+1

O2 Sensors are there to make sure the car is not running too lean or too rich. They are about $100 for the sensor + whatever you mechanic charges to fit it in.

Also get your ECU checked out.

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get rid of the pod and the BOV...

I had the exact same issue ... removed the pod and bov as per research and info found on this site and presto I started getting 400-450kms to a tank if I keep it off boost around town, 350kms with a heavy foot. On the freeway FC is great for instance I've been from Wollongong to Penrith twice this week and have only used 2/3 of my tank so if you include the few trips I've also done around town that is heading towards 600-650kms from this tank...

car = 33 gts-t

modz = full stainless steel exhaust (split dump, HF cat cannon etc), 300x600x80 FMIC running through stock, kings springs, sway bars and interior modz.

next modz = remap of thes tock ecu and a major service

get rid of the pod and the BOV...

I had the exact same issue ... removed the pod and bov as per research and info found on this site and presto I started getting 400-450kms to a tank if I keep it off boost around town, 350kms with a heavy foot. On the freeway FC is great for instance I've been from Wollongong to Penrith twice this week and have only used 2/3 of my tank so if you include the few trips I've also done around town that is heading towards 600-650kms from this tank...

car = 33 gts-t

modz = full stainless steel exhaust (split dump, HF cat cannon etc), 300x600x80 FMIC running through stock, kings springs, sway bars and interior modz.

next modz = remap of thes tock ecu and a major service

Get rid of the BOV, your pod will already give that 'Choo' noise.

I got a tuned (remapped ecu) R34 GTT with new spark plugs, full turbo back exhaust ..standard bov, O2 sensor and cooland sensor were checked and said to be fine and the car does not run rich as it's been tuned and I get 300Kms inbetween refills which is 50 litres exactly.

The mechanic looked at my fuel lines and said they look fine (no leaks) so I've no idea what else it could be .. probably just normal for my driving style which is around town mostly under 70Km/h but I don't baby it but don't redline it either ie. rarely go above 4200rpm but I do hit boost quite early (under 3k) Oh yeah the car's had a full service done on it too..all oils changed, belts etc

I don't get how a bov can reduce fuel economy......My mates got a S15 with Apexi pod, turbo back exhaust, intercooler and a few other little things. His still gets like 400 to 450 km's out of a tank with giving it abit here and there.

I don't get how a bov can reduce fuel economy......My mates got a S15 with Apexi pod, turbo back exhaust, intercooler and a few other little things. His still gets like 400 to 450 km's out of a tank with giving it abit here and there.

probably cause the s15 is 4 cylinder 2000cc while the skyline is 6 cylinder 2000/2500cc. lol

ive noticed after putting in a bov on my 34 the economy on it has dropped 50kms...

what does changing a o2 sensor do?? the smell of my exhaust has been abit strong even before i had the bov on

the o2 sensor isn't necessarily linked to fuel economy as i understand it, but more so linked to emissions control ... don't get me wrong it plays some part in fuel economy I'm sure ... (there is a link/thread somewhere by SK in regards to this)

the biggest culprits are vent to atmo BOV and pod ... as they make the AFM readings sent to the ECU incorrect which causes the ECU to dump loads of fuel in an attempt to compensate when it doesn't need to...

i onyl get around 280 out of a tank. doesnt really matter how i drive it. will eventually be changing injectors, O2 sensor, new cat and remap and see how it goes. i do have pod and atmo but like the sound they make together.

I don't get how a bov can reduce fuel economy......My mates got a S15 with Apexi pod, turbo back exhaust, intercooler and a few other little things. His still gets like 400 to 450 km's out of a tank with giving it abit here and there.

if you've got an atmo bov then the air is being released into the atmosphere instead of being recirculated into the AFM.. this gives the AFM fake readings and puts more fuel in (as its designed to do) if you want good fuel economy and an atmo then you need to go MAP and remove the AFM.. This then takes the reading from the manifold

  • 1 month later...

got a GTR fair few performance mods running 385hp@4 wheels. two pods blow off valve blowing straight out an rarely ever only get less than 350km to a tank an thats only if i'm only doing short runs an thrashing the crap outer it, 200km/h ect. long trips i usally get bout 500km sitting on bout 120km/h an still passin cars at bout 180 ect not goin to easy. think its mainly in the tune an ecu, got pfc. by the way isn't the redline sorta like a factory shift indicator???? =P hehe

After a tune and 02 replacements its all about the way you drive.

My 33 has around 250rwk and i can cruise and get around 400km from a tank. That number can more than half if i drive hard. The 400km from a tank has not changed from when it was under 200rwkw because when driving normally i'm not ever boosting.

I get about 450-520km out of the tank depending on my driving style. But usually I get approximately 500km out of a tank including some hills driving... doesnt change much even with normal driving.

Damn, I only get 240Km on a full tank on my GTT. It is a pretty stock setup with a few minor mods that came with it from Japan. Upgrades are mainly, Blitz ECU, Blitz EBC, Blitz Timer, HKS FMIC, Trust Air Filter and an HKS SSQV vented. When I got it I immediately changed oil and coolant and installed my defis to monitor everything, the car boost fine to redline and I do drive hard but not shifting on redline maybe around 6-6500rpm. I know the vented BOV is causing some bad consumption and I am also thinking that I should get a power FC as the Blitz ECU is not tuned for my octane level. So my next step is to get the power FC and change my plugs for some new NGK BKR7s gapped to 0.8mm and see if that helps. I am also going to be recirculating the BOV, clean my throttle and replace my stock intake pipe with a metal one and redo my intake manifold to face forward and reduce the intake cold pipe route same time. Hopefully after all this with a new tune my mileage should be better. We'll see.

  • 1 month later...

I have a R33 s1 with a fmic, 3inch exhaust, pfc, Z32 air flow meter (cleaned it to) and avcr

i have replaced the O2 sensor and removed the pod airfilter and refitted the standard air box with a k and n filter and also removed the atmo bov and refitted the standard plumb back bov.

The PFC was tuned with the atmo bov fitted is this going to prevent me seeing better fuel economy? or will the pfc adapt to the changes over a couple of tanks of fuel? or do i need to have the thing retuned?

I wish it were just the O2 sensor in mine (not hooked up at all due to Microtech)

I get around 350km to fuel light from full, with new plugs and oil, and not really getting over say 4500 rpm. That is with an RB25 in a GTS-4 though.

Might try turning EBC off and see if its any more economical at stock boost (it's tuned for 18 psi though)

The cat was blocked though which unblocking did see a small rise in economy.

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