350z roadster drinking more fuel then it should

[Y23DRH]

I have had my 2005 350z roadster almost a year and still most i see is

 

20.7mpg on motorway and 19.6 around town

 

and thats driving sensible

 

but my car has a few upgrades

 

Custom Remapped by jez @ horsham devlopments

Full exhaust system with no restrictions and centre bit cut out and straight pipe fitted

Decatted

Megan racing tubular manifold

Paddle clutch

Horsham developments 5/16th plenum spacer

Lightened fly wheel

Short shifter fitted

And blitz lm induction kit with decent heat shield

Plus many more mods but none that would cause the car to drink fuel :/

 

 

then i spoke to some one who has a super charged 350z and he gets around 20mpg :/ how can i be getting 20mpg been told I should get 27 to 30mpg ??? Nit sure if thats correct but almost every one i have spoke to says must be something wrong :/

 

I have been to nissan had the car fully serviced and checked over they said everything is ok :/

 

The car is not over fuelling or running rich I'm at a loss to what it could be

 

I only use shell v power aswell

 

Any suggestions would be very appreciated

 

Many thanks dan

Edited July 15, 2013 by F4ABP

[370Ad]

You should easily be able to get 35mpg cruising at 70 on the motorway. If something was wrong with the engine wouldn't Jez have picked this up?

 

It also made good power too if I recall?'

[Y23DRH]

You should easily be able to get 35mpg cruising at 70 on the motorway. If something was wrong with the engine wouldn't Jez have picked this up?

 

It also made good power too if I recall?'

 

 

Yea the car made very good power and the torque curve was very good aswell jez run it 12 times on the dyno with no problems at all :/

 

The car has been fully health checked etc all came back ok ???

 

 

[Y23DRH]

I just cant seem to find what the problem could be or if there is one at all ????

 

 

[M13KYF]

best place to start is to go back to Jez and get the map checked. You should be getting better mpg.

 

 

Either that or have you tried 5th and 6th gear on the motorway

[Y23DRH]

best place to start is to go back to Jez and get the map checked. You should be getting better mpg.

 

 

Either that or have you tried 5th and 6th gear on the motorway

 

Yea i will go back to jez get him to check it all over

 

And yep tried every thing i can to see if i can get it to be better on fuel :/

[Lincolnbaggie]

How are you measuring the mpg?

[M13KYF]

I was joking about the gears

[M13KYF]

How are you measuring the mpg?

 

 

good point

 

 

Have you reset the counter whilst on the motorway

[Lincolnbaggie]

The computer is not very accurate. Mine always shows DTE of 0 when there is at least 150 miles left in the tank. How many miles do you get between fill ups and how much fuel does it take to fill up?

[Y23DRH]

I was measuring the mpg off the computer but i have also kept a log of total miles on the trip computer Aswel i zero back setting a and b every time i fill up but when come to next fill up lucky if i get 240 miles from a tank :/

 

[Y23DRH]

I takes just over £100 to fill up and i get 240 miles from it :/

[bamdc2]

hmmm does seem a little low even with all those upgrades. Jez would surely know if there were any fueling issues.

 

I consistently get 22/23mpg around town but I havent specifically reset the mpg for a long run. Definately get more than 20.7 though!

 

Must be the way its mapped?

[Aliensurfer]

Small fuel leak somewhere maybe?

[Lincolnbaggie]

I takes just over £100 to fill up and i get 240 miles from it :/

 

Ouch, that does sound low. I assume no leaks?

 

Oops, beaten to it

Edited July 15, 2013 by Lincolnbaggie

[squanchy]

Wait a minute, I rarely get more than 16mpg around town... I just assumed this was normal.

[M13KYF]

Wait a minute, I rarely get more than 16mpg around town... I just assumed this was normal.

 

 

its on the motorway the OP has the issue

[NeilMH]

Presume the re-map was done after the mods?

[Y23DRH]

No fuel leaks that i can or smell and nothing on the floor when i leave the car for the day in once space either i have also had nissan check the car over and they said they couldn't find any thing wrong :/

 

[Y23DRH]

Presume the re-map was done after the mods?

 

 

Yep all mods added then went for a remap

[Lincolnbaggie]

You say its got a paddle clutch? Assume an auto then. Is it sitting in the correct gear?

[Y23DRH]

I will reset every thing on next fill up and see what the results i get

 

 

And i will check under the car make sure none the fuel hoses are leaking or weeping and also check the fuel pump and tank for leaks but if it is leaking its not detectable at all :/

 

 

Its had new spark plugs correctly gapped

New fuel and oil filter Among lots of other bits

And also new coil packs to see if that would sort it but still nothing :/

[Y23DRH]

You say its got a paddle clutch? Assume an auto then. Is it sitting in the correct gear?

 

No its a manual 6 speed gt roadster

 

Has a very heavy clutch its either on or off no in between

 

Im really at a loss to what the problem could be

[jjt]

The mpg does vary massively depending on whether its around town or on a run. On a run its around 34mpg, but around town about 21. Id say if all I do to a tank is urban driving, I would get about 260 miles out of the £80 tank, up to 360+ on a run.

[Y23DRH]

The mpg does vary massively depending on whether its around town or on a run. On a run its around 34mpg, but around town about 21. Id say if all I do to a tank is urban driving, I would get about 260 miles out of the £80 tank, up to 360+ on a run.

 

I get 20.7 mpg on motorway i should be getting 35mpg ??? So something must be wrong then ???