XF EFI Chewing fuel Need Help.

[Anonymous]

I'm new to these forums and these are probably pretty dumb questions but I'll ask anyway.

I have an EFI XF Stationwagon 85 with extractors. The bottom end is from an XE and the head is in very good nick (it is an EFI head BTW). It has a Borg Werner 3 Speed transmission from an XE i think its the 35. The car is powerful (relatively) especially at high revs. The standing off the line is adequate considering what it is - but I am having a real bad time with fuel consumption.

About 290 kms from a 65 litre tank. I dont drive like an idiot.

What are the likely cause of this woeful economy rate.

I'm guessing a worn or incorrect cam or maybe the fuel regulators shot (how do I test it) it might even be the computers fried and I'm in limp home mode but this is unlikely.

I have a slightly lower than normal temp thermostat but I have also had the correct one and still no avail.

My exhaust tip colour is dark grey/black but not blue and there are no leaks in the exhaust.

BTW I don't really know where the fuel/air mixture screw should be either I have it at 2.5 turns out.

Also the engine does not stall if I have the air/fuel screw all the way in either - is this a problem?

All the injectors are good and I have a new thick film ignition module.

Timing is at 10 degree TDC.

Can anyone please help.

 

[addo]

It needs asking if your timing set is up to scratch, and if the balancer timing mark is verified.

Neither will make a mega difference, but you are likely to find your economy losses in a whole host of small deficits compared to "blueprint" specs. Also, it is worth advising that the fuel economy in these motors, is never close to that of modern cars.

Cheers, Adam.

 

[xctasy]

Check this too. Re-read backlash's comments at http://fordsix.com/forum/viewtopic.php?p=138819&highlight=#138819

 

[Anonymous]

Thanks Guys - I see that a few little changes from XF EFI spec have led to some drastic losses in economy - oh well - I will try to implement the ideas given starting with a hotter thermaostat and a dyno tune.

Thnaks Again.

 

[wagon]

The best I get around town in my XE wagon with XF EFI is 17L/100km - driven VERY GENTLY! Because my darling lady drives it usually, and she has a lead foot, it typically returns around 19-20L/100km. HOWEVER, fuel pressure is cirtical (NO closed loop (O2) control on these motors), the calibration of the airflow meter is critical (maybe a problem if the 'mixture' screw can be fiddled for little or no effect).... Check for vacuum leaks and poorly done 'repairs' too. A stuffed oil cap gasket, or a leaky dipstick tube (or any other vacuum leaks) will cause lean running, and lazy mechanics will typically pull the lid off the airflow meter and richen it up- puts the mixtures out everywhere! Best of luck, and sell your lead boots.

Kendall.

 

[Anonymous]

Our XF carby auto gets lousy economy too, about $30 in petrol for a 120 km round trip. I think they are all like that.

 

[xt falcon]

my xe motor returns 4kms to a 1L driving like a hoon with a 600 holley, i thought i was getting bad economy but after seeing yous i feel beter. i think the only way to get good fuel economy is to use a closed loop efi set up, so when you are light on the gas peddel your motor can run lean. it might pay for it self if you drive a lot?