Subaru maff sensor fail
 

Hi all,

Can any one help with a maff sensor question
Yesterday driving home I lost all power or boots and engine management light was flashing but it did not store any codes carried on driving and EML stayed on
Done a quick scan with dashcommand app and came back with cylinder 1,3 & 4 misfire but nothing about maff sensor.
I disconnected the maff when car was running and stayed running apart from a drop in revs but picks straight back up it didn't cut out when unplugged is this correct?
It seems like the car is in limp mode when connected and struggles to go past 3000 rev and 30mph but soon as I disconnect it the car runs better but not perfect.

Any help would be appreciated

Also can I drive the car with the maff disconnected?

Thanks

Do not drive with a dodgy maf or you will be replacing the engine along with a new maf sensor, its not uncommon for them to go faulty and not bring the eml on,

Hi mate,

Thanks for the reply and letting me know don't drive the car I have been looking on ebay at some maf sensors and the aftermarket ones are about £25-£30 and the Denso ones vary in price from about £60+ is it best to go for a Denso one? Thanks

I would stick with an original denso one buddy , where abouts in the country are you?

Hi mate,

I'm from South Wales Merthyr Tydfil. I have added a link below of a video of the issue I'm having

Hope it works

The car seems to be in limp mode and the turbo is not getting any boost I think
But soon as I unplug the maf sensor the car runs a lot better but still not full power back.

The 3 k rpm limit is the ecu trying to protect the engine i honestly would not be driving that untill a new one is fitted, fit a genuine new part and reset the ecu

Ok great will get the Denso one ordered
Thanks both for the help :)

Hi All,

Gutted changed Maf sensor and the car is still the same any one have an idea what else it could be?

Thanks

Here is a video of the newMaf Sensor now working but car still seems to be in some kind of limp mode :(

Car still in limp mode? Any one have any ideas?

What's that whooshing noise sounds to me like Ya have a big boost leak in one of your intercooler pipes
That would explain your misfire cels too
I can hear it in both vids

I thought first of all boost leak but I have checked all pipes and all seem fine. I have changed the Maf sensor thinking it was that as the car would stay running when unplugged think that was another issue That was there too
the whooshing seems to kick in when the 3 k rpm limiter starts its not there when I start off from stationary

Could it be the turbo or actuator? I don't have any smoke out of the exhaust to indicate turbo though

Someone correct me if I'm wrong, but when you replace the MAF, aren't you supposed to flash the ECU?

All I have done is turn the light off with my obd code reader

How do I flash the ECU?

Thanks

I 'think' you just disconnect the battery for a few minutes.

Ok great will try and disconnect the battery tomorrow just hope that works

Cheers

Hi all

Disconnected battery and left it off for about an hour and the problem is still there
Any one got any other ideas I can try?

Thanks

if we are on about the car in your avatar then the ECU is NVM type so just disconnecting the battery wont reset it.

Hi thanks for the reply yes it's the pic in my Avatar

Is there any easy way I can reset the ECU do you think it's just the ECU needs resetting due to the Maf sensor change?

Just need to get it out of this limp mode it's in to see if the sensor has solved the problem

Thanks

Changed the MAF on an 02 bug didn't need to reset ECU same symptoms as you BTW

did you buy a new replacement?

Hi mate,

I sourced the Maf from a friend and he said it was working with no issues and when the new one is unplugged the car does cut out is this correct? as were before with my old one it used to keep running with it unplugged

So from the vids I have put you was having the same whooshing sound and like in limp mode?

Thanks

Recently I had exactly the same problem as you, OBD reader said misfire on 2,3 & 4 but of course didn't say why. After changing plugs, maff and a few other bits there was no change so I systematically took everything apart (I mean everything) and worked through it piece by piece.

To check the pipework properly means taking most of it off. I found a tiny split in a vac pipe, so changed that. I found I had overtightened the silicon inlet to inlet trumpet and ovalled the trumpet so it was leaking slight amounts of air. Not so critical on big throttle openings but bad news at low revs. I reshaped that. Taking off the fuel filter was the biggest shock. Initially fuel just dribbled out from one pipe but not the other. After a good shake a load of water and muck came out, so I fitted a new filter. The car was transformed, and is probably running better now than it ever has.

So it wasn't just one thing wrong but a series of small problems that eventually caused a big one.

Hi mate,

Thanks for this awesome piece of info I will get a new fuel filter ordered and have a good check of all the vac lines to see if there is any leaks there

I will let you know how I get on

Thanks

Check the filter before buying a new one.
If it is full of crud have a look in the fuel tank via the access plate for the fuel pump as that is where the natural low point is on the tank, it may be full of grit, snad, water etc. With the filter off you can see if you have flow.

Even check the simple stuff like plug leads are fitted properly, the Coil pack is good and accelerator cable is lined up on the pivots.

Thanks mate,

Will check fuel lines tonight and remove filter see what is in there and if there is any flow of fuel.

When I was getting the cylinder misfire I thought it was the spark plugs or coil packs these will be the next thing I check after fuel filter and lines.

Will let you know how I get on

Thanks

Keep us updated.

Hi All,

Not long got in from checking things took fuel filter off and seemed ok no crap coming out of it and the fuel was flowing through the lines

I check the leads were connected ok on spark plugs and all seemed ok

so I starting looking at vac hoses I removed the intercooler and the under there was the Y hose think it's called that any way one side was detached but couldn't see it from the top tightened up jubilee clip and now it seem to be working great :)

Thanks so much for all the help off everyone much appreciated

I'm well happy now :)