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Cabin air sensor valve. Has anyone running boost have problems with the one way valve failing under boost? When I get into boost, it sounds like there is air coming from down there, as if the one way valve is failing under pressure.
It makes the normal sucking noise under vacuum at idle.
I need to disconnect and see if there is a difference...

Thanks

As far as I know there is no one-way valve on that vacuum line. You can install one though.

mooseheadm5 wrote:As far as I know there is no one-way valve on that vacuum line. You can install one though.

I meant to put this in forced induction....
If thats the case, and there is no valve, that may explain my crazy lean issue. I guess that would be considered a boost leak..... I always thought a boost leak would cause a rich condition... lets see what happens....

time to disconnect and see what happens..... for the longest it was not connected.

If the restrictor is gone from the cabin sensor line (and it probably is), it will run lean and produce the symptoms you describe. Find a restrictor and install it.

Talk about happy right now. I've been searching for this lean running gremlin for months.......
I will be purchasing one today....

Thanks

I am a little confused with this post. The vac for the Heating / ac and power brakes is generated by a mechanical vac pump running off of the camshaft. A lean condition on the engine would not relate to a problem with the hvac system. What leads you to believe that there is a crazy lean condition? The reason I ask this is because by the very design of a diesel, it normally runs lean, because there is no throttle plate. Could you please elaborate on your symptoms? When a diesel runs rich, you will see the black smoke, but lean? Is it low on power ? From your first post, it sounds like a boost leak. But that would cause more black smoke.

george_jetson wrote:I am a little confused with this post. The vac for the Heating / ac and power brakes is generated by a mechanical vac pump running off of the camshaft. A lean condition on the engine would not relate to a problem with the hvac system. What leads you to believe that there is a crazy lean condition? The reason I ask this is because by the very design of a diesel, it normally runs lean, because there is no throttle plate. Could you please elaborate on your symptoms? When a diesel runs rich, you will see the black smoke, but lean? Is it low on power ?

This is my fault, sorry. This post was supposed to be in forced induction.
Its a boosted m30, not a turbo diesel.

So I disconnected the vacuum to the cabin air sensor and while the car's idle is much smoother, it still goes full rich to full lean under full throttle and falls on its face.
It turn out that the cabin sensor was so shot that it was no more than a vacuum leak.
I talked to Corky Bell and he said that regulators built before a certain date have had issues with the shims. Don't remember what the date was, but mine is pre that date.
He told me to send it in for a rebuild with his latest technolgy.

So that's were I am at this point.

The cabin sensor is just a vacuum leak. That's all it does as far as the motor is concerned. There is supposed to be a restrictor in the vacuum connector that keeps it from leaking too much vacuum. That's more than likely what you are missing there.

What are the consequences of removing the cabin sensor permanently?

Atlant wrote:What are the consequences of removing the cabin sensor permanently?

No heat?

I guess you could remove the vacuum line and that would probably make heat regulation a slow process.

BTW, the e34 has a tiny little blower to pass cabin air over the temp sensor.

grey ghost wrote:...I talked to Corky Bell...

Did this catch anyone else off gaurd? Like, THE Corky Bell?

I should go start reading his book again, I only got it last Christmas....

Glad you've solved your issue tho! I remember your post a while back about it.

demetk wrote:

Atlant wrote:What are the consequences of removing the cabin sensor permanently?

No heat?

I guess you could remove the vacuum line and that would probably make heat regulation a slow process.

BTW, the e34 has a tiny little blower to pass cabin air over the temp sensor.

My cabin temp sensor is disconnected, and I have a colder than stock thermostat and my heat is crazy...

unt0uchable wrote:

grey ghost wrote:...I talked to Corky Bell...

Did this catch anyone else off gaurd? Like, THE Corky Bell?

Call his company, sometime he answers the phone himself. He is very available and gives some serious tech support over the phone. I wasn't trying to name drop at all. I just wanted to let people know were the knowledge was coming from.

grey ghost wrote:

unt0uchable wrote:

grey ghost wrote:...I talked to Corky Bell...

Did this catch anyone else off gaurd? Like, THE Corky Bell?

Call his company, sometime he answers the phone himself. He is very available and gives some serious tech support over the phone. I wasn't trying to name drop at all. I just wanted to let people know were the knowledge was coming from.

That's awesome. Good to know, for sure. Thanks for sharing!