Zd30 maf sensor location

[Steveg]

I have read many discussions about zd30 patrol maf sensor being downstream of engine breather and getting coated in oil from engine breather , even with a catchcan ,and having to remove and clean . My question is why not switch these 2 around and then it will be upstream and not get coated in oil ??? Am i missing something ?? Thanks steveg

[mudski]

The Maf is "upstream" of the breather outlet already. They don't get coated in oil too, not sure how this is possible, they get coated in dirt... It may get a little oil when engine has just turned off as some of the gases might travel up the intake towards the MAF. But not enough to make it oily.

[Steveg]

Thanks for that , it didnt make sense to me , obviously i got the wrong end of the stick . So after the nads mods , does a patrol zd30 last or do they still self distruct ? And is it worth cleaning inlet manifold every 150k ?? Just trying to get an idea on older/high km zd30 patrols , thanks

[Steveg]

I just looked up some thread s and again one by ynot and he says maf sensor gets contaminared by engine breather emissions and i assumed this meant breather is upstream . This isnt the only post that says that , so i guess its a common misconception.

[the evil twin]

I just looked up some thread s and again one by ynot and he says maf sensor gets contaminared by engine breather emissions and i assumed this meant breather is upstream . This isnt the only post that says that , so i guess its a common misconception.

Tony is correct, the MAF Sensor is "upstream" from the breather and it does get coated by emissions,

In a turbo charged engine such as the ZD30 there is a condition called turbo surge.
Turbo surge is much less problematic in a VNT or VGT such as the ZD30 than that of a conventional Turbo but it does still occur.
The surge exists when a rapid unloading of the engine and thus the turbo means the high pressure induction air in the intercooler plenums (approx 32PSIA) can momentarily surge back thru the turbo inlet and air induction pipes towards atmosphere and therefore contra to the normal flow.

This momentary contra flow means that over time the MAF will get a slight coating of engine breather residue which also encourages any fine particulates post air filter to also adhere to the sensor.

If you pull out a ZD30 air filter after a few thousand K's and have a look you will see an almost circular patch of black oily residue on the filter where it faces the induction plumbing.
This residue deposit is also due to the turbo surge and gives you an idea of what is also coating the MAF sensor.

[the evil twin]

Deleted my post because I wasn't thinking and put up the wrong info... dumbass!!!

[mudski]

Not saying its incorrect ET but I find it hard to see how air flow can go backwards in the air intake, whilst your driving. Even with this "turbo surge". My old ZD never saw black deposits on the air filter.

Just never seen or heard of this.

Besides the black on the outside of the filter element is from the intake side of the air box, via snorkel. If it were from the engine, it should be on the inside of the element.

Doesn't compute in my tiny brain anyway...

[the evil twin]

Aaagh, thanks mudski... mucho embarrassed now... got myself confused with threads there and posted incorrect shit.

Perhaps try Dr Google for "Turbo Surge" for better (and more accurate) explanations of the effect.

[mudski]

Thanks for the welcome
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