Bad fuel economy

[athenian]

So I've recently got myself a full custom system from SpeedFab, header to backbox. One thing I've found strange is that even though the header is decat, the eml light hasnt come on (No o2 spacers were installed). In addition, the exhaust fumes seem to smell of fuel alot more than usual decat cars and the fuel efficiency is terrible! not that I expect it to be super eco but I can barely get 150miles to the tank regardless whether I do city or motorway driving. Any ideas?

 

[abbey132]

mapped? running way too rich by the sounds, shouldnt be messing too much with exhaust or intake without kpro or k100,

 

[bxlheathsupra]

Mines mapped but does stink.. get it mapped to sort it

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[athenian]

I know ultimately mapping it is the way forward (which I will do once funds allow) but I was wondering in case anything else is playing up as I have no eml with decat

 

[Crazylegs]

Yeah needs mapping mate. A decat will make it run very rich and it'll hum of fuel but a remap should help improve the economy too. If it's any consolation I barely get over 150 to a tank either lol.

 

[Johngreen537]

Decat will lean it out surely?

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[Crazylegs]

I'm sure mine was running very rich when it went it for its remap?

 

[bxlheathsupra]

I get around 300 to a tank, 400 on a motorway run. But stinks terrible with decat. When i put my car in its fine

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[Grano]

Are you sure one or both of the o2 sensors weren't damaged? It should be throwing a light with that setup. And I would have thought it would run lean, not rich. Either way, you really need a remap asap.

 

[CW05TEG]

I'm running a spoon 2-1 decat with the oem 4-2, with an RM01A and oem intake. No EML light on despite not being mapped, no 02 sensor spacers. Fuel efficiency seems to be very similar to running with the cat. Also it was noise tested at Cadwell at just 90db @ 5000rpm.

 

[athenian]

Are you sure one or both of the o2 sensors weren't damaged? It should be throwing a light with that setup. And I would have thought it would run lean, not rich. Either way, you really need a remap asap.

Thats what I found strange.. on eml. You may be right regarding the o2 sensors, is there anyway to check they arent faulty? Then again surely a faulty o2 would throw the eml on. Sounds like i'll need to remap it sooner than I was planning, I wanted to change to rbc before a remap.

 

[Grano]

Thats what I found strange.. on eml. You may be right regarding the o2 sensors, is there anyway to check they arent faulty? Then again surely a faulty o2 would throw the eml on. Sounds like i'll need to remap it sooner than I was planning, I wanted to change to rbc before a remap.

If you get Kpro you can disable and ditch the secondary o2 sensor anyway. My tuner says its rare but sometimes the primary wideband can be faulty without an eml. If it's done a fair mileage it wouldn't hurt to replace it anyway, they don't last forever.

 

[athenian]

It's only done 47k mileage but it may possibly be that, thank you! Is there any way to check the primary o2 before i go and buy a replacement?