Anyone know anything about mass airflow sensors?

[Nute]

I've come to the conclusion that I can't delete this thing. I think it's made by Bosh, it's on my BMW, originally housed in an ugly plastic box between the intake filter and the induction manifold. Appears to have a spring loaded metal flap in it which is opened progressively as airflow increases, I assume to vary the timing.

It was originally mounted so that the pivot spindle around which the flap rotates was vertical, so the flap thing moved on the horizontal plane - not influenced by gravity. Any idea if I can rotate it so the spindle is horizontal and the flap thing will move in the vertical plane? The flap thing doesn't have much mass and it still closes against the stop when rotated. 

[Catteeclan]

9 hours ago, Nute said:

I've come to the conclusion that I can't delete this thing. I think it's made by Bosh, it's on my BMW, originally housed in an ugly plastic box between the intake filter and the induction manifold. Appears to have a spring loaded metal flap in it which is opened progressively as airflow increases, I assume to vary the timing.

It's measuring the amount of air being drawn into the engine. It sends a varied voltage to the ECU which can adjust the fuel trim and timing. Not something you can do without.
 

9 hours ago, Nute said:

It was originally mounted so that the pivot spindle around which the flap rotates was vertical, so the flap thing moved on the horizontal plane - not influenced by gravity. Any idea if I can rotate it so the spindle is horizontal and the flap thing will move in the vertical plane? The flap thing doesn't have much mass and it still closes against the stop when rotated. 

It could influence the running but couldn't say how much.

This a kit car project or something?

[Nute]

Thanks, it’s on a BMW K100 so bike not a car.
 

It’s big and ugly so was looking to get rid but changing its orientation will help. I’ll just try it and see I guess. 

[Buckster]

Yes you can rotate it. There are airbox delete kits or there used to be that had a 90 degree bend pipe that also required the sensor to be rotated.

[Nute]

Thanks @Buckster, Seen the delete kits for the 16v versions but mine is an 8 so apparently they don't work due to the different fuel injection controls, so I have to keep the sodding thing. Ill try it rotated and see what happens

[Buckster]

20 minutes ago, Nute said:

Thanks @Buckster, Seen the delete kits for the 16v versions but mine is an 8 so apparently they don't work due to the different fuel injection controls, so I have to keep the sodding thing. Ill try it rotated and see what happens

Deleting it is a pain because you then need to have the fuel management reprogrammed and even then they tend to run like crap, you can service the unit though if it gives problems.

[Pedro]

2 hours ago, Nute said:

Thanks @Buckster, Seen the delete kits for the 16v versions but mine is an 8 so apparently they don't work due to the different fuel injection controls, so I have to keep the sodding thing. Ill try it rotated and see what happens

It's not a mechanically beautiful bike anyway, to put it gently, so might as well show that off.

If you can hide it, hide it. If you can't hide it, exaggerate it 

[Buckster]

52 minutes ago, Pedro said:

It's not a mechanically beautiful bike anyway, to put it gently, so might as well show that off.

If you can hide it, hide it. If you can't hide it, exaggerate it 

Exactly, paint the engine bright red.

[Nute]

I cannot argue with that ... but I like it 

Its this thing ... I could totally get rid of it if I bought a set of 16v throttle bodies plus the 16v fuel injection unit ... but I have to do everything the hard way. Looks better from the other side.

[Catteeclan]

Could you make something to cover it.
You could replace it with MAP sensor but you'd need some clever bugga to create a new map for the ecu.

[Buckster]

47 minutes ago, Nute said:

I cannot argue with that ... but I like it 

Its this thing ... I could totally get rid of it if I bought a set of 16v throttle bodies plus the 16v fuel injection unit ... but I have to do everything the hard way. Looks better from the other side.

The standard box is plastic, that is custom.

[Buckster]

There should be a cone filter on the end of the elbow.

[Nute]

Yeah, sorry should have said that isn't the std manifold, the plastic one is in the bin.

Originally there were two plastic boxes, the collector box that goes on top of the throttle bodied then another one which has the MAS in it. To use the MAS exposed I need to make a bracket for it as it's just hanging in the breeze at the moment. I'll weld a tab to the frame and bolt the bracket back to that. 

The original collector box had a series of washers in each of the 4 internal tubes to restrict the airflow - its been someone's A2 bike at some  stage.