Exhaust manifold

[win.walid]

hi

How do cracked exhaust manifold affect MPG???
my 2.2 vectra b do 16 mpg roundtown verrrry bad , I have changed the (air filter, spark plugs, O2 sensor and no check engine light), but have a cracked exhaust manifold..any advise will be appreciated

 

[IDI AMIN]

hi

How do cracked exhaust manifold affect MPG???
my 2.2 vectra b do 16 mpg roundtown verrrry bad , I have changed the (air filter, spark plugs, O2 sensor and no check engine light), but have a cracked exhaust manifold..any advise will be appreciated

A cracked manifold will mean exhaust gases will escape where they are not supposed to which will affect acceleration so this will affect mpg i also know that a faulty EGR valve can cause poor mpg i have had this problem but along with a faulty coil pack as well

So in answer to your cracked manifold get another one you can get one on ebay for between £20 - £25 pounds
The cracked manifold is a common problem with these engines i changed mine a couple of years back no more problems there since

 

[win.walid]

Thanks..

 

[win.walid]

But what do you say about the effect on the O2 sensor..

 

[IDI AMIN]

But what do you say about the effect on the O2 sensor..

Your 02 sensor will pick up improper readings with a cracked manifold once you have replaced the manifold then you see how it affects 02 sensor
at worst you will need to replace 02 sensor depending on its age. i would recommend buying an NGK brand 02 sensor if you need one

 

[win.walid]

Thanks but I had replaced it with NGK one 6 months ago because of the problem of poor MPG but I felt no difference, but now I believe that poor MPG is from the cracked exhaust manifold.