MAF unpluged ?

Only had the TD4 about a month or so and was a little unhappy with the MPG I was getting about 30mpg . Fitted a synergy 1 no better really other than a litttle more pull above 2000rpm.

Today I decided to have a look at air filter and found the MAF sensor unpluged.

Should I feel the differance after plugging back in and should the mpg improve with it in ?

Also why would anyone disconnect it ?

If you fitted the Synergy how did you do it and leave the maf disconnected?

The answer is absolutely the maf must be connected.

If someone else did it perhaps it is do far gone out of spec that the default almost limp mode is better!!!

You'll probably find the MAF is faulty but it should have put the MIL light on too?
Some people unplug them when faulty as it sets the engine ecu to a default reading to keep engine running.

The synergy 1 does not have the MAF connector so I dident notice it was disconnected.

Maybe some one had a synergy 2 on it at some point and disconnected it before selling it.

Anyway I have now reconnected it and seems to be running fine will have to see if there is any improvement. Im going to turn the synergy off and see if it feels any different.

Just to confuse you a little further, if it were to run worse with the Maf connected you could assume it was knackered, if it makes no difference it could be ok or it could still be knackered. The only way to confirm it's actually giving a signal is to read live data. I suppose a significant improvement in Mpg could be taken as an indication it's working but only if you can be certain that the improvement isn't down to others factors.

If you have a manual gearbox a failed or disconnected Maf won't light the MIL

Disconnecting doesn't cause a 'limp mode'.

Yes its a manual so no MIL light on. It does seem to be running a little better but that could just be my imagination.

I have been getting about 30 MPG if the maf is ok what should I expect to get i drive with a light foot and most trips are about 20 miles on dual carrigeways

30 is ok and about right

You should get at least 34 - I am with sone fast stuff and one injector is a bit off.

Some report up to 42mpg!?

42 no way

cremator said:

42 no way

Click to expand...

I can get better than 42mpg - but only on a long motorway journey.

Never get anything like that doing mixed driving.

Town driving knocks it right down.

long motorway driving yes but not mixed driving

Hi , 25 to 30 town driving in cold climate , 41 on a run keeping to 60 mph !

Quick update on my unplugged MAF (now plugged in). I have done about 50 miles mixed driving today and the engine seems to have a much smoother feel and pulls better below 2k rpm. I put £50 in when fuel light came on so will see how the MPG goes in the next few days.

Bear in mind that temperature has improved a bit recently and might account for better fuel figures. I would expect to see at least mid 30's with your top gear journeys.