P00BD - Mass air flow too high - ONLY WHEN WARM

[paule3d]

Hi.

Does anyone have any idea why this code would show up only after the engine has warmed up?

I've tried a different MAF sensor, and Intake Air Temp sensor - no change. There's no *obvious* air leaks.

As mentioned only happens when engine has warmed up.

It has had EGR delete by Vantuner, and I've blocked EGR, in case that might be relevant.

Thanks for any advice.

[knobby1]

Hi.

Does anyone have any idea why this code would show up only after the engine has warmed up?

I've tried a different MAF sensor, and Intake Air Temp sensor - no change. There's no *obvious* air leaks.

As mentioned only happens when engine has warmed up.

It has had EGR delete by Vantuner, and I've blocked EGR, in case that might be relevant.

Thanks for any advice.

You still may have a split boost pipe or intercooler...they can be hard to find sometimes.

Lord Knobrot

[paule3d]

Thanks, Ive bought a load of washing up liquid, I'll set about all the pipes with it looking for bubbles!


The weird thing is, I had a massive air leak at the manifold EGR pipe hole, turns out the o-ring went missing after wrestling to get EGR pipe in manifold.
That flagged turbo underboost error at first.

I then tried a generic o-ring - it was better but could feel slight air leak at idle.
Ordered a proper ford one - still minor air leak ffs so I used both o-rings and then it was fine (no air leak - *at idle).

But Ive just realised. It will idle all day without issue. Maybe when I accelerate uphill, more air is forcing some out. How the heck to test that without having my hand in engine bay to feel the air when driving uphill :/

Think I'll have to get manifold off and bodge something to block EGR hole!
Some plate steel that wont bend in middle when screws done up tight with layer of rubber as a gasket maybe. At least then the b*stard EGR pipe wont be a big hassle to get back on after engine maintenance. (It's RWD - maybe its easier on FWD).

Cheers

[metalworker0]

i confess that i don't quite know what these pipes will be doing at tickover not knowing much about turbos ..but i would have thought they will be pulling as vacuum at tick over, and you would be testing with brake cleaner ..squirting it on ...and looking for change of rpm as the cleaner gets sucked in through the point of leakage.
at higher rpms ..it would change from a vacuum to a positive pressure as the turbo comes into effect...that's my understanding.
As far as i know most sensor signals are ignored until it gets to a certain temperature, this is how the system runs, when its cold its called "open loop" ignoring the signals and using its ECU data base to keep engine running, once warmed up it goes closed loop and uses the information from the sensors to adjust things. works out if the sensor signals are within spec ..if not, puts a light on in the dash to tell you so, followed by limp home mode if serous error.

i don't mind being corrected on this ..

all the best.mark

[paule3d]

Thanks, I'll use some brake cleaner spray, thats safe for the turbo then?

Regards

[metalworker0]

Well you are not going nuts with the spray ..you are sort of putting small amounts on where you suspect the leaks are ..wait a few seconds for rpm increase..if nothing ..move onto the next area

you could increase the rpm to say 1800..then it would be positive pressure and you could then use the soapy water test.

but if you ask me ...myself ...
the following is a a job that should be done on these vans at least every couple of years or 15,000 miles, what ever comes first

I would be taking all the pipework off including intercooler ..and giving it all a really good clean inside and out ..during the clean you can inspect each piece individually for damage or cracks..or rubber sealing gaskets ..ripped, torn , deformed etc ...
What you will find ------- lots of oily gunge..
I use very strong solution of biological washing powder...sort of 1 cup full to every pint of boiling water ..intercooler has to be taken out...it will probably take 2- 3 pints

block one end ...pour it in let stand for five mins ...shake it ..pour it out and flush with hose.

you could use paraffin , jizer or petrol ..but that would be far more expensive than cheap lidl / aldi washing powder.

note your "Mass air flow sensor" is in the pipework ..this may be gunged up ..use a paint brush with soapy water to clean it .

all the best.mark

[paule3d]

Thanks for the tips. I still havent got round to it as have a lot of other higher priority issues in life at the moment!

I'll hopefully have a chance in a few days and try remember to update here.

Regards

[Tranny-Manny]

Hi pal,

Did you manage to get to the bottom of the issue? I have very similar symptoms

Cheers

[paule3d]

I didn't

It's just occurred to me I've had this on 3 different MAF sensors with slightly different triggers.

First it only started happening uphill in 6th.

Changed to 2nd hand sensor off ebay, the uphill thing was gone. But it happened after driving at 85 for a while (long trips to Scotland in the night on empty motorway).
Wasn't fussed about this.

Changed glow plugs on RWD (lots of extra work and everything is in the way) and my mate was a bit rough moving everything in the engine bay... :/
So I'm thinking it could be wiring harness or pipes.

The fat intake pipe to throttle body was squashed around a lot so I'll take that off for a visual inspection,
but I 99% dont think it could be that as I had a huge air leak as the EGR to inlet manifold o-ring got sucked in to the engine (oops!) when putting it all back together one day. And that leak didn't make any different to this code. so I doubt a tiny crack in the big engine air inlet pipe would trigger it if that huge leak didnt.

So I'm gonna have to trace the wires from MAF sensor to ECU. Maybe get some contact cleaner spray on the connection as oil went *everywhere* once when I forgot to put the cap back on after filling

But TBH the way my mate was with the wiring harness it wont surprise me if there's a split somewhere.
Dont see how different engine loads and temperature could make a difference but need to rule it out one way or the other.


*EDIT* I forgot about Mark's reply previously. I'll take the lot off and give it a good clean one day soon, there is a bit of oil around the ends of the intercooler.

Will reply here once I've sorted it, if ever haha. But I need to else my DPF will end up blocked again! :/ and I'm sick of doing a rolling restart to remove limp mode to overtake some zombie doing 17 in a 20 (I'm in Wales....!)