On the Christmas morning drive to visit the family, when I arrived and pulled to a stop, noticed that the engine idle was far from normal.

 

Its a 2003 Octavia 1.6 Ambient, with the BFQ engine. Usually, idle is somewhere around 700-800, but it was sitting there, fluctuating between 1500 to 1800, after a short time, the revs would drop really low (around 500), and it would seem like the engine is about to stall, then it returns to normal idle for a bit, then the process repeats. A gentle tap of the accelerator to raise the revs over 2000 also starts it off again.

 

No warning lights have come on on the dash, and a quick check with Torque on my phone shows no faults.

 

From having a quick look and listen, the only thing that appears different is that there is a bit of a hissing sound around the throttle body area, particulally the little pipe that connects under the oil beather then connects to the top of the intake manifold. I pulled this off, and it is sucking in lots of air through there. Not really noticed if it has been doing this beofore or not. (Marked on attached picture)

 

Any ideas of things to investigate?

Edited 27 December, 201411 yr by jonnyboy93

It will the usual vac / breather hose split under the inlet manifold I'd expect.....

When you pull the pipe off at the throttlebody end, with the engine running, if you cover the open hole at the end of the hose, does the running of the engine change or does it hiss?.

 

I have had dealings with my daughter's boyfriend's Leon 1.6 with this problem, and it turned out to be a split in the pipe,

Blocking the end of the pipe did not make any difference, the hissing continued, as did the varying idle. It does sound like the hissing is coming from underneat the covers in that area of the engine.

 

Is there a guide or instructions somewhere of how to dismantle/remove the inlet manifold parts to get at the troublesmone hose that may have split? Could do with removing some of the front of it anyway to change the spark plugs that are burried beneath it as well.

Getting the inlet manifold off is bit of a "meccano set" on this engine, you would be smart to buy a few hours on the vag electronic service manual and download what you need so you can print it later. From memory, I don't think the Haynes manual is much use on this if I remember correctly.

 

This may help, but is not vag elsawin - http://workshop-manuals.com/skoda/octavia-mk1/drive_unit/1.6_l/75_kw_engine_fuel_injection_and_ignition_system/mixture_preparation_system_electronic_inj.gas/fuel_injection_system/removing_and_installing_parts_of_the_injection_system/