bad fuel economy

[jt-1994]

hi guys got my first car last year its a series 1 xr6 with the vct motor. Ive always had pretty bad fuel economy around town (mainly due to short trips) but lately its jumped up a fair bit more to 19L per 100. I drive resonably smooth and dont plant it everywhere. On the highway it can manage around 11L per 100. Its also got a rough idle but drives fine, ive changed sparkplugs and leads, 02 sensor, cleaned throttle body, new airfilter, and reset the ecu any help would be greatly appreciated

[BHDOGS]

Try changing fuel filter under car

[_Ben]

I'm having a similar issue. Went to a mechanic today and got told it COULD be the inlet manifold gasket. My economy wasn't as bad as yours though

[FGII-XR6]

could be the coil pack, the S1 coil packs ( same as the EF) weren't the best. they changed them in the S2 but unfortunatly you can't use a S2 coil pack in the S1

[FERG_51]

My bet is the regulator filter is blocked. get a fuel pressure test to confirm, high pressure is usually caused by this, quiet common in AU,s.

[jt-1994]

so i changed the fuel filter this morning keep u guys updated thanks for all the ideas so far

[jt-1994]

Also i tried to get a few of the mechanics around my area to do a pressure test but none of them wanted to do it for me and insisted it would be injectors and that its highly unlikey for the regulator to be blocked is there anyway for me to check at home?

[FERG_51]

Originally Posted by jt-1994

Also i tried to get a few of the mechanics around my area to do a pressure test but none of them wanted to do it for me and insisted it would be injectors and that its highly unlikey for the regulator to be blocked is there anyway for me to check at home?

Ive had many AU's with this problem. Any decent workshop could do a fuel pressure test. Try a Ford dealer, they are not as bad as many on this forum sugest, get a quote shouldnt cost too much.

[Vincenzo]

Just ti throw a spanner in the works;

are you using the trip computer to get your l / km or are you doing it from the petrol pump - km travelled over litres filled?

[jt-1994]

FERG_51: thanks for the input ill give ford a go

Vincenzo: no trip computer im doing the calculations with km travelled and litres used

[FERG_51]

Originally Posted by jt-1994

FERG_51: thanks for the input ill give ford a go

Vincenzo: no trip computer im doing the calculations with km travelled and litres used

No worries, its a fairly quick check and if in spec you can rule this out and start looking else where.

[Evgeni]

Hi jt,
If you are going to take it to Ford and they end up hooking it up to a scan tool, a look at the fuel trim numbers will confirm your problem for you. Ideally, they should be at 0, so a positive number means that the computer is trying to add fuel to deal with a lean condition. Negative number means that the computer is taking fuel away to deal with a rich condition. You'll either be looking for a vacuum leak or sorting out the fuel delivery as Ferg said based on what these figures are telling you.
I kow you said you changed your O2, but just make sure that the wiring is intact. If a part of that is exposed and touching the body, that is, if it is shorted, it will be reporting a false lean condition when it really isn't. Short term fuel trim reacts to the O2, Long term reacts to the short term...etc

[tim_pato]

Post your progress!

PS It isn't the fuel pump. It is the fuel regulator which has a higher setting on the*VCT*engine. Before flash tuning of the*ECU*was available to the AU, a common-ish mod for*VCT*owners was to use a standard fuel reg. The*VCT*engines run very rich from factory.

Quoted from somewhere, thought it may help

[jt-1994]

Ok thanks for the tips I found a mechanic who is willing to do the fuel reg test I take it in on tuesday and will go from there just a another quick question, when doing the pressure test where should the guage be plugged in to? Tje return line? Just want to make sure he tests from thw right area btw thanks for all the help so far this is a great forum

[jt-1994]

went to the mechanis this morning tested the fuel regulator and that checked out fine with 300kpa might try the coil next as it runs a bit rough anyway

[mik]

dragging brakes?

[FERG_51]

Originally Posted by jt-1994

went to the mechanis this morning tested the fuel regulator and that checked out fine with 300kpa might try the coil next as it runs a bit rough anyway

Im on hols atm but pretty sure fuel pressure at idle is 250 kpa so 300 would be high. Ill check the ws manual on monday if you like.

[jt-1994]

Dont think brakes are dragging would it be audible?
Ferg_51: the fuel pressure is correct because xr6 came with a slightly higher fuel pressure from factory

[mik]

not always.

[falconnut]

Originally Posted by _Ben

I'm having a similar issue. Went to a mechanic today and got told it COULD be the inlet manifold gasket. My economy wasn't as bad as yours though

my mechanic also finally found this to be the problem for rough idle/missing.

my fuel economy was great on the highway but average around town, hopefully when i get it done next week it will be way better.