no boost and searching revs help plz

[lee1972]

hi

 

have a 2004 mk 1 ovtavia vrs

 

around 2 weeks ago my revs started searching and had not boost and bit lumpy 

after around 15mins it went back to normal

 

last night happened again

revs were on tick over around 2000

and no boost at all

 

tries it this morning

no boost but revs gone back to normal

also seems bit lumby

 

any ideas please

thanks

Edited 30 March, 2016 by lee1972

[KenONeill]

Yes:-

1. Get the fault codes read; they're only golden, not crystal.
2. Write in English. For example, I've never heard of "searching revs" in a car engine before, and the closest thing I have heard of to it is not compatible with a loss of turbo boost.

[lee1972]

sorry

 

rev counter going up and down

 

from 1000 to neally nothing then jumping to 2000 and down again

all over the place and not sitting at 1000 when on tick over

[Rsphill]

Possible coil pack failure. Any codes or eml light on.

[YellowCar]

Revs climbing up and down sounds airflow related to me. For example mine did it when a hose popped off my sai. But as Ken says that doesn't necessarily tie in with loss of boost. Definitely need a scan, some codes may not throw the EML on.

Edited 30 March, 2016 by YellowCar

[SuperbTWM]

These engines are prone to having air leaks which can cause the revs to hunt at idle but probably not that much. As mentioned above i would check to see if there are any misfire codes logged.

 

Have a butchers around all the pipework anyway, an air leak could explain a lack of boost aswell

Edited 30 March, 2016 by SuperbTWM

[lee1972]

hi

 

thanks guys

the boost started working again last night all off a sudden why driving

but was still ticking over between 2000 and 25000 revs on tick over

 

there are no warning lights on

my friend is bringing the machine back from work tonight so will see what that says

 

thank you

[Rsphill]

A scan is always a good starting point. If there are codes showing up these could be old. Depends when it last had a scan.

[KenONeill]

Ok, that sound a bit like "hunting", which would mean over-fuelling on low (off-boost) throttle settings, so you see why I don't think that's compatible with a boost leak.

 

Or an issue with the idle stabilisation control, or the throttle position sensor, or even the engine temperature sensor...

[deanest]

I had a similar problem with mine a while back.

 

It could be worth just listening for an air leak. I wish I had started with that instead if the air filter/spark plugs/rocker cover gasket 

my leak was around the suction jet pump. My understanding (NOT A MECHANIC) was that it was involved with the Vacuum from the turbo?

 

Anyway theory right or not it worked for me. Good Luck.