Vacuum leak
 

Okay... my 8 is having some serious vacuum leak issues. It's occuring between the intake manifold and the airbox. I've changed all of the gaskets and still can't seem to find it. Anyone else have this problem or know of a way to fix it?

Also, when I hit the gas pedal, you can actually hear the sucking sound... almost like it has a cold air intake on it (it doesn't). Power has dropped WAY off as I'm assuming the air to fuel mix is all fubared up.

not a single gasket between the intake manafold and the airbox...

so what did you change????

beers :beer:

^^ 2X. Unless he meant the "O" ring on the MAF.http://www.mazdamaniac.com/portal/smiles/icon_shrug.gif

Also, you can't have a "vacuum leak" outside of the intake manifold.

Why?
 

What makes you think you have a leak?

You say you are having "issues" but you don't say which....

FYI, they all make that insane sucking noise at idle - is that your problem?

I'm sure we can help if you can elaborate.


S

Okay... they do all make the suckign sound no matter what. When I hit the gas pedal there is a distinct inflow of air sound around where the evap system is... the big plastic tube type thing running from the throttle body back to the motor... I wish I had the book infront of me to get the exact description (I'm a racer/driver, not the greatest mechanic). The sucking sound is there at idle, but when I press the gas pedal it's almost as if the car is taking a deep breath from areas that it shouldn't.

As for the gaskets, they are all along the evap system (generic discription above).

The sound is new to the car. When I say the car is having issues, there is a distinct lack of power especially above 6k rpm (I'm going 90 mph when I should be 125 mph). It threw a code, but now I can't get it to throw the code again to read it.

All help is appreciated.

was you dad here a while back asking ?s..

it might be helpful if you give us any info at all... is it stock??

i have a few ideas, but you are giving us nothing to work with.

beers :beer:

Yeah... that was my dad giving a good effort to help on a troubled race weekend.

As for the car, it is completely stock. It's used for SCCA club racing so it does see speed and consistent high revs. I had the evap system off to install a fuel test port as I had to replace the fuel line that runs beneath the evap system itself., when I put it back together, it started making the "wooshing" sound when I it that gas pedal. That's why I replaced the gaskets as I though maybe I pinched one.

NOt sure what other info I can tell you... if you ask, I'm sure I can fill you in... otherwise, the car is completely stock from the motor standpoint.

if you have never removed the air box or touched anything around it. it is a tough call..

1 check to see if the maf is secure and seated properly.
2 make sure the accordain clamps are tight... mine came back from the dealer a while loose.

3 on a long shot make sure the vacume hose (for the vdaf)
that attaches to the bottom of the intake is still on..


btw, the hose to the ear trick should help find the location

beers :beer:

Thanks again... I dropped it off at the dealer Saturday but they can't find it either. It's easy to hear where it's coming from but there isn't anything there that it could be other than a hair-line crack.

Very aggrivating.

try the hose trick... check between the intake and the block...

a few mismachined intakes have been seen...

beers :beer:

Will do... thanks!!

Okay... verdict is in... it was the Mass Airflow Sensor due to K&N oil gumming it up. As soon as a new one went on, the car perked right back up.

You should be able to clean the MAF sensor. Use rubbing alchohol

use carb cleaner

what he said, and you need find out why the oil is getting back.

beers :beer:

Okay... the fun continues. The MAF was replaced and helped a little, but didn't fix it completely. Will remember to clean it periodically. Turns out there is still a sucking sound coming from the area of the (correct term) Extension manifold upper and lower. Car still lacks serious power anywhere after 7k rpm.

I had each of these off to install a fuel test port. I'm hoping they are cracked. I will be placing an order for the new parts this morning in hopes to get them on for this coming weekend's race. I love overnight shipping charges.

Any more suggestions? I am going to take a look between the intake and the block as well... haven't done that yet.

have you put a tube in there yet to locate the noise? a stethescope? if not quit whatever else you are doing and do that- locate the origin of the noise.

What, exactly, did you remove?
You didn't remove the aluminum part of the intake I presume (it is practically impossible to remove with the engine still in the car).
When you re-installed the upper manifold, did you verify that the pegs were in place? O-Rings?
Did you remove the APV for any reason? Injector rail?
If you had the P2s out, you might have a leak there.
Most likely, you removed the jet air tube and it is open.

There is a vacuum connection on the side of the throttle body (right behind the accordian tube) the connection is tucked underneath. If this hose has a leak anywhere along it it will not open the vfad duct in front of the car at 7,000 RPMs and it will cause a sucking sound... and potentially slightly less power. ;)

It would also cause really rough idle. RPMs swinging between 1500 and 500.