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Author Topic: Very Poor MPG. Help Please.  (Read 5698 times)

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Mal

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Very Poor MPG. Help Please.
« on: 05 October 2009, 19:28:56 »
Definately believe I now have a MPG problem. When I purchased the car I just thought they were bad on fuel. Now looking through the various posts I have now come to the conclusion 18mpg is not good. Car runs fine. No lumpy tick over. Oops sorry the car is a 2.5 v6 cd. Took her out for a darn good thrashing, but still it returns poor fuel. Now suspect this is the reason the previous owner got shot of her. Car was sold to me from a dealer. Non Vauxhall, just a small independant. Got it cheap anyhow plus it was a few months ago, so I'm not bothered about taking her back and creating a stink. My fault as I should have done a bit of research before hand.

Still does anyone have a clue what could be causing this. She has had 1 owner and full Vauxhall service history right up to 91,000. Car is now on 93,000.

Cruising on the motorway at 70mph. revs @ 2500 & the onboard computer instant fuel consumption shows 22mpg. £40 gets me about 160 miles.  :'(
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Time is a great teacher, but unfortunately it kills all its pupils ...


When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.

feeutfo

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Re: Very Poor MPG. Help Please.
« Reply #1 on: 05 October 2009, 19:36:28 »
18 is a hard driving round town figure on the 2.5 imho. First things to check is both multi rams are working and that the the vac system the supplys them is fully connected and not leaking. Have a look through maintenance guides, paper clip it and make sure the servicing is up to date. There as a few causes so come back if no joy, but multi rams is my bet to start with. :-)
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rustym95

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Re: Very Poor MPG. Help Please.
« Reply #2 on: 05 October 2009, 19:39:48 »
Hi were are you some one may be ble to come round and have a look, I know that if the time belt is getting stretch they  can use more fuel with no out come until it breaks,but im sure some one would have a look for you :y :y
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joshwyatt

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Re: Very Poor MPG. Help Please.
« Reply #3 on: 05 October 2009, 19:48:21 »
It might be worth having it fully serviced, just because it says it's been serviced it may not have been. New plugs, oil and filter, new fuel filter and air filter may help improve the cinsumption. But as chrisgixer said, the best thing is to do a paperclip test, if no faults are thrown up I'd get it serviced. Possibly the breather system may be blocked, that can affect consumption too.
« Last Edit: 05 October 2009, 19:48:40 by joshwyatt »
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Mal

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Re: Very Poor MPG. Help Please.
« Reply #4 on: 05 October 2009, 19:53:41 »
Cheers, I will have a go at the paperclip test tomorrow and see what shows up.  :y
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Time is a great teacher, but unfortunately it kills all its pupils ...


When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.

Richard A

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Re: Very Poor MPG. Help Please.
« Reply #5 on: 05 October 2009, 20:04:01 »
Just as a guide my '98 2.5 petrol Elite auto with 163k miles does 32 mpg at 70 mph motorway speed.
Average over the last 700 miles, motorway and London centre 28mpg, so 22 is bad, as said update your details with location as someone maybe near who could help.
regards
richard a
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barclay03

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Re: Very Poor MPG. Help Please.
« Reply #6 on: 05 October 2009, 20:19:06 »
As others have said - might be best gettin someone in the know to have a look over everything  :y

Just to throw in some stats i average around 22mpg around town in the 3.0 MV6  :-/
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Ziad

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Re: Very Poor MPG. Help Please.
« Reply #7 on: 05 October 2009, 21:34:16 »
Well, I get about 16 mpg with my 3.0 on short runs  ::) ::) :-X
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feeutfo

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Re: Very Poor MPG. Help Please.
« Reply #8 on: 05 October 2009, 21:59:17 »
Quote
Well, I get about 16 mpg with my 3.0 on short runs  ::) ::) :-X
Very possible on short runs while driving hard round town. Auto box and weight of the car coupled with the could start mapping all drink fuel. But who cares with the prices your paying out there.

If you or the op have any steps in the rev range esp at 4 k check multi rams on the inlet behind rad and back of plenum. Give it a good(very good) rev and watch them move. If they dont you will get lack of performance meaning you press the pedal more to get the car going. Which drinks even more fuel.

Poorly timed cam belt, poor servicing, blocked filters can all have an affect.....imho. :-)
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tunnie

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Re: Very Poor MPG. Help Please.
« Reply #9 on: 05 October 2009, 22:03:35 »
getting 35 mpg out of mine on average per tank at the moment, thats with about 1 hour of stop-start traffic in total each day, a 2.5 would get the same on the motorway bit, not sure if it would be the same in heavy traffic.
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Ziad

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Re: Very Poor MPG. Help Please.
« Reply #10 on: 05 October 2009, 22:05:16 »
Quote
Quote
Well, I get about 16 mpg with my 3.0 on short runs  ::) ::) :-X
Very possible on short runs while driving hard round town. Auto box and weight of the car coupled with the could start mapping all drink fuel. But who cares with the prices your paying out there.

If you or the op have any steps in the rev range esp at 4 k check multi rams on the inlet behind rad and back of plenum. Give it a good(very good) rev and watch them move. If they dont you will get lack of performance meaning you press the pedal more to get the car going. Which drinks even more fuel.

Poorly timed cam belt, poor servicing, blocked filters can all have an affect.....imho. :-)

Thanks for the advice Chris  :y Multi rams work very well, thank you ... but I got a heavy (VERY heavy) foot AND a thumb which plays with that famous S switch a lot  ::) ::) :P

Service is done by a top bloke whom i trust and who really knows his stuff. Actually timing was bad when I bought the car and when he changed the changed the whole kit, he set it up properly (using that locking kit of course)

Anyway, as you say, with the prices we pay for petrol here, who cares  ::) ::) ::) And oh, I forgot ... sometimes I even see 12 - 13 mpg  :P
« Last Edit: 05 October 2009, 22:06:19 by ziad »
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Bent valve

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Re: Very Poor MPG. Help Please.
« Reply #11 on: 05 October 2009, 22:17:28 »
Quote
Definately believe I now have a MPG problem. When I purchased the car I just thought they were bad on fuel. Now looking through the various posts I have now come to the conclusion 18mpg is not good. Car runs fine. No lumpy tick over. Oops sorry the car is a 2.5 v6 cd. Took her out for a darn good thrashing, but still it returns poor fuel. Now suspect this is the reason the previous owner got shot of her. Car was sold to me from a dealer. Non Vauxhall, just a small independant. Got it cheap anyhow plus it was a few months ago, so I'm not bothered about taking her back and creating a stink. My fault as I should have done a bit of research before hand.

Still does anyone have a clue what could be causing this. She has had 1 owner and full Vauxhall service history right up to 91,000. Car is now on 93,000.

Cruising on the motorway at 70mph. revs @ 2500 & the onboard computer instant fuel consumption shows 22mpg. £40 gets me about 160 miles.  :'(
Try not thrashing it. Works wonders for the MPG :y
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Mal

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Re: Very Poor MPG. Help Please.
« Reply #12 on: 06 October 2009, 10:08:30 »
LOL. You know what I mean by a thrashing.  8-) Blow away the cobwebs  :y

Right the paperclip test shows a fault.  :'(

19   Incorrect RPM Signal

What does this mean. Simples or bad fix.  :-?

Cheers Mal
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Time is a great teacher, but unfortunately it kills all its pupils ...


When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.

Elite Pete

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Re: Very Poor MPG. Help Please.
« Reply #13 on: 06 October 2009, 10:13:22 »
Quote
LOL. You know what I mean by a thrashing.  8-) Blow away the cobwebs  :y

Right the paperclip test shows a fault.  :'(

19   Incorrect RPM Signal

What does this mean. Simples or bad fix.  :-?

Cheers Mal
Its an easy fix Mal, 19 is crank sensor and its common. I would suggest buying a genuine one and here's the how to ;)
http://www.omegaowners.com/forum/YaBB.pl?num=1174321688
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Mal

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Re: Very Poor MPG. Help Please.
« Reply #14 on: 06 October 2009, 10:57:02 »
Looks like i'm off to Vauxhall then :'(. Got to go anyway as I was looking around the engine and also found a split pipe. Group of 4 that go into the thing above the ECO TECH on engine. Cut cable back and took her for a drive. Still poor MPG. Now I have foun another pipe split. Tiny gauge one this time. Comes from the front near rad. Looks like it is from a sensor by the vacuum thing. It goes all the way to the back of the engine to the HBV ::).  Sucking air in like a goodin. :y

New pipe then I feel can only make her feel better :D
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Time is a great teacher, but unfortunately it kills all its pupils ...


When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.
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