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        General >> Problems >> bad mpg on a 2.9 v6 12v
        
(Message started by: JimmyJaffa on Apr 26^th, 2008, 10:28pm)

Title: bad mpg on a 2.9 v6 12v
Post by JimmyJaffa on Apr 26^th, 2008, 10:28pm

Hi, i have just bought a 2.9 12v and have had it for a week and find that it is using so much fuel that i need my own refinery at home, im probably getting about 16 mph at the mo, has anyone got any ideas of what it could be as im sure i should be getting about 24 mph, many thanks, jim.

Title: Re: bad mpg on a 2.9 v6 12v
Post by TiberiuS on Apr 27^th, 2008, 1:16am

Jim. 16mpg, not good :o

Not familiar at all with the 12v but two good places to start are engine coolant temp sensor, this will cause the ECU to run really rich thinking the engine's stone cold all the time, killing MPG. Also lambdas (not sure of the lambda setup on the 12v), bad lambdas can sometimes read the mixture as lean when it's really ok making the ECU put lots more fuel in than it needs to. Plenty in the forum archives about this type of problem, well worth searching the forum.

One of the more 12v savvy guys should be able to help more :)

Regards, Bruce

Title: Re: bad mpg on a 2.9 v6 12v
Post by JimmyJaffa on Apr 27^th, 2008, 7:53am

many thanks for that i will do some searching

Title: Re: bad mpg on a 2.9 v6 12v
Post by Snoopy on Apr 27^th, 2008, 7:56am

Check the air filter make sure that is clean/ new plugs rotor arm and plug leads can cure some of the low MPG problems but I would suspect either the MAP sensor or the lambda sensors .. they are quite easy to do on the 12v give them a good soaking in releasing fluid over night when it is cld get the correct cut out spanner and out they come . The thermostat on the 12v is also VERY easy to replace with little coolant loss .. if you change it get the proper FMD one it has the rubber sealing ring on it .. no need for a gasket.
Also run a couple of bottle of injector cleaner through the old beast and use good petrol .

Title: Re: bad mpg on a 2.9 v6 12v
Post by harry.m1byt on Apr 27^th, 2008, 4:28pm

That last item, injector cleaner worked on mine, but not nearly such poor mpg as yours. I used STP petrol injector cleaner, the one you add to a tank full at an annual service. mpg increased from low 20's up to 28 to 30 depending how driven.

Title: Re: bad mpg on a 2.9 v6 12v
Post by gozz on Apr 27^th, 2008, 10:35pm

Jim.
Yes 24 mpg is not unthinkable,Snoopy has given you the correct info particularly regarding the MAP and HEGO sensors,these being the greatest cause of really heavy fuel waste.Check also that there is sufficient vacuum present at the MAP sensor,ie no blockage or pipe breakage.
GOZZ.

Title: Re: bad mpg on a 2.9 v6 12v
Post by JimmyJaffa on Apr 28^th, 2008, 10:42pm

Hi. thanks for all the replys but i may of cracked it, today my engine started to missfire badly which i had noticed on occasions on tick over , lifted the bonnet to find sneaky ht lead leaking to earth. so new set of leads fitted, will post results after a few days of driving, jaffa .

Title: Re: bad mpg on a 2.9 v6 12v
Post by Tons_of_fun on Apr 29^th, 2008, 5:38pm

hi jaffa,just wondering about your MPG.! Are you getting that figure driving "around town" ? ? .If so the best you can hope for will be about 18 mpg increasing to around 31 on a good run.I,ve had 4 x 2.9 12v in both granada & scorpio forms & i love em, bullet proof mechanicals & capable of doing big mileage with the basic of maintenance,but alas they are VERY thirsty.As the guys said coolent sensor or lambda are the usual culprits when economy goes south.Hope you get it sorted.Enjoy your motor...Craig :)