Chipping

[solarman216]

I thought the maf can only detect temp as a coefficient of air flow , as it's just a heated element that gets chilled by air flow.
So if it gets chilled a lot (or conned into believing that )the ecu delivers more fuel accordingly :thumbs

nice idea but not possible, the maf can only determine air volume with a heated element reference to an unheated element to determine air flow as per the parameters in the ECU, you need another device to determine temperature, Rick

 

[stinka]

So how does the ecu determine a boost fault then if there is no sensor or pressure ?

 

[makeitfit]

nice idea but not possible, the maf can only determine air volume with a heated element reference to an unheated element to determine air flow as per the parameters in the ECU, you need another device to determine temperature, Rick

I was nearly there :augie The second element makes sense :thumbs

 

[makeitfit]

So how does the ecu determine a boost fault then if there is no sensor or pressure ?

Do the newer T2 have an extra sensor somewhere ? No way of doing it on mine circa '97

 

[geoffdown]

Do the newer T2 have an extra sensor somewhere ? No way of doing it on mine circa '97

Or my x reg 2000 2.7tdi the ecu cant do anything bout it anyway unlike on the 3l which I belive the ecu controls the waste gate but on the 2.7 might as well piss in the wind as it cant do anything about this over boost code:thumbs

 

[stinka]

Do the newer T2 have an extra sensor somewhere ? No way of doing it on mine circa '97

The 2.7 etdi only has the maf, crank sensor, temp sender, throttle position sender, needle lift sensor, ecu and fuel pump

Nothing more on even late ones

The maf works out the boost pressure somehow guys as that was the fault on mine

 

[solarman216]

So how does the ecu determine a boost fault then if there is no sensor or pressure ?

not exactly sure, but if the boost fails then the lambda sensor will see a difference that I guess the ecu can work it out from that, and do not forget the maf will be well down to what it should be referrence revs, Rick

 

[stinka]

No lamda sensor on a td27 mate

 

[solarman216]

No lamda sensor on a td27 mate

So I guess no Maf either, so does it really say if no boost? Rick

 

[makeitfit]

MAF yes Lambda NO :thumbs
Never seen that code either come to think of it.You sure that's not a 3.0 code :augie

 

[stinka]

MAF yes Lambda NO :thumbs
Never seen that code either come to think of it.You sure that's not a 3.0 code :augie

I had the boost fault for about 3 months until I swapped my dodgy non gen maf, don't you remember all my threads about limp mode and cutting out, posted all over the boards

It is a common td27 tdi fault

Like I say my old boss is a wizard and knew what it was straight away and like I say he has a proper consult 2 Nissan handheld which I saw all the fault codes and parameters on

 

[makeitfit]

Remember the issue yes but forgot that the error code was boost fault.
Just can't see how it's anything monitored though :nenau

 

[solarman216]

MAF yes Lambda NO :thumbs
Never seen that code either come to think of it.You sure that's not a 3.0 code :augie

simple, if you have a maf and an ecu and no or poor boost, then for a given engine rev the maf will show lower than expected air flow, Rick

 

[rayf3262]

simple, if you have a maf and an ecu and no or poor boost, then for a given engine rev the maf will show lower than expected air flow, Rick

Rick is bang on there, an excess airflow error (over boost) can only be due to to much "suck" by the turbo or a faulty MAF.
So the MAF is not measuring boost, but range checking airflow against predefined parameters.