Exhaust manifold

win_walid

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

win.walid said:
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 (y)
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

win.walid said:
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(n), but now I believe that poor MPG is from the cracked exhaust manifold.🙂