mfa fun and games

[White2505 0]

Have tried a search but this particular issue does not seem to be covered.

 

My mfa on the mpg1 setting is having a bit of a wobbler.

when it does work it gives me about 18mpg currently (woefull but accurate and possibly another probelm!!)

however it is regularly showing 99.9 from start up for various lengths of time from 1mile to the entire 15 mile work journey

 

the tube IS connected at the back of the dash and within the engine compartment, all the other vacuum pipes have been checked for leaks because of a previous idling problem.

 

something is throwing it a wobbler any wisened individuals got some sage advice??

[billinjah 0]

my valver does this

[sciroccotune 0]

vac leak i would suggest, check pipes

[White2505 0]

all pipes have already been checked.

is there something that the pipes connect to that allow the enigne to run smoothly that still gives this effect??

[bighands 0]

along the same lines, mine shows between 9-13 max MPG all the time, what would cause this??!

[billinjah 0]

my display is also rather feint (splg!) when the lights are on? not so in the g60

[sciroccotune 0]

which car you got, 16v etc?

[Lippy 0]

something to do with the earth on the back of the clocks?

 

:?:

[Supercharged 2]

along the same lines, mine shows between 9-13 max MPG all the time, what would cause this??!

 

Check the Vac pipe that feeds the clocks...

[White2505 0]

all the vacuum pipes have been checked and are definately okay.

each of these pipes connects to something and it must be that something that's causing the problem.

This begs the following question there is a vacuum pipe coming out of the ecu unit on my valver, now if I've lost vacuum to the clocks giving the 99.9mpg issue then I must have lost vacuum elsewhere in the system and am I now losing power/optimum timing??

[White2505 0]

okay latest update and time for you knowledgable types to put on your thinking caps please, I have swapped out the ecu today and the same problem persists. I KNOW the vacuum pipes themselves are not leaking.

I also figure if I'm losing vacuum to the MFA display then surely I must also be losing vacuum to the ecu. This in turn must surely be throwing out the timing meaning I'm losing power/economy.

The brakes are working extememly well so I know I've got vacuum to the master cylinder.

So what should I be looking too next? What's the most likely candidate for the failed piece and why do you think that?

[White2505 0]

okay so after some more driving the following appears to be the case.

 

9/10 times the mfa starts offering what appears to be an accurate mpg figure. (around 10-18mpg depending on how cold the engine is starting from)

however once the engine temp reaches about 65-70ish the mfa steadily climbs to 99.9mpg.

this suggests to me that something within the vacuum circuit which is temperature dependant has thrown a wobbler.

initial thought is the isv although, the old girl is idling just fine and I would have thought that if the isv had gone nuts then my idle would have gone to rats, especially in this super cold weather. (unfortunately I don't have a spare so I can't easily swap it out just to see.)

My fuel consumption is also knackered (20 mpg tops) I'm not running rich and the 4 fuel injectors have just been replaced so are known good.

Any suggestions greatly appreciated.

[Supercharged 2]

What engine is it???

[White2505 0]

apologies 1.8 16v

[MattWilde 10]

mine would do this and it turned out to be buggered clocks, changed the lot and now get accurate reading no matter how depressing.

[White2505 0]

Can't help feeling that based on the initial accurate reading of the mfa and the definate change once the temperature is met this is something more than the clocks.

Once combined with the poor mpg it definately suggests to me something vacuum related in the engine bay having a wobbler onve the engine starts to warm up.