I've got a hunting idle, when sitting there at traffic lights it just sits there hunting, also when revving up it slows hesitates slightly at around 5000-6000 RPM? It's had a new MAF, genuine Bosch a little while ago, however I'm adamant that it's still the problem. Although I occasionally get error code P0171 (lean running on cylinder 1) and the EML comes on? Any ideas? MAF, coil pack, something else? Car is a 2003 Octavia VRS.

Mafs can be supplied faulty, usually aftermarket jobs but worth a look,

I'll be popping out later, so I'll unplug it again, and see how we go. One other thing, if I unplug the MAF when the car is running, should it cut out?

if it is hunting at idle and you have a lean code then you most certainly have a VAC leak. very common failing, take the top engine cover off and check the Y shaped pipe to the right of the block, also the pipe that goes from the Y pipe down under the manifold. there are a few of the smaller pipes that can pose a problem but start with the big one first. forgot to add that these pipes get really soft over time due to the crank gases and split or break up. if you squeeze the pipe it will be slow to go back into shape if it is FUBAR

Edited 13 February, 201313 yr by karlbar2k

I'll be popping out later, so I'll unplug it again, and see how we go. One other thing, if I unplug the MAF when the car is running, should it cut out?

Yeah should run ok I believe

if it is hunting at idle and you have a lean code then you most certainly have a VAC leak. very common failing, take the top engine cover off and check the Y shaped pipe to the right of the block, also the pipe that goes from the Y pipe down under the manifold. there are a few of the smaller pipes that can pose a problem but start with the big one first. forgot to add that these pipes get really soft over time due to the crank gases and split or break up. if you squeeze the pipe it will be slow to go back into shape if it is FUBAR

I've got a tiny oil leak from around that area possibly, they're related?

it might not be Oil as such but the crank case crud which is oily. how many miles has the car done? if the Y pipe has never been replaced then those are the two pipes to start with.

if you look on here (ignore the scribbles - that was for something else) its to the right of the red coming off the head with the star on it (replacement in silicone from eurojet racing - lots of alternatives nowdays though)

you'll have to ignore the gubbins at the front of the block as well as that is the LPG system.

Edited 13 February, 201313 yr by karlbar2k

This one is better

it might not be Oil as such but the crank case crud which is oily. how many miles has the car done? if the Y pipe has never been replaced then those are the two pipes to start with.

87k now, never replaced, the pipes have 2002 on them, car is an 03 plate.

it will be like putty then. replacements from VAG are not too bad but if ever you go to a dealers parts department ask them to pricematch TPS

it will be like putty then. replacements from VAG are not too bad but if ever you go to a dealers parts department ask them to pricematch TPS

Ok thanks mate, much appreciated . I've got a picture of roughly where the oil/gunk goes, I'll post that in a minute .

Edited 13 February, 201313 yr by DKB69

Oil can be seen down there. There's a little pipe underneath that lot, which is where I think it's coming from?

there is one that goes from under the bottom of the inlet manifold down to the bottom of where that Y Pipe disappears into the crank case which is subjected to Boost and VAC it could also be from the "Suction Jet Pump" which is down there as well

How much am I looking at roughly?

Depends which pipes but not loads

Depends which pipes but not loads

So am I right in thinking, there's two little pipes under that cover, they travel up and go into the Y shaped pipe?

This ones from RobClubley and is a big help, look at the light blue

from 18 the crank breather there is a T piece with a check valve which can fail or get clogged causing it to not close properly under boost (causing loss of boost - I stripped mine and cleaned it so it was better but not perfect) the thin pipe that goes up to the manifold if split will leak boost and vac and is a good candidate for extra check valves when you replace it (also dealt with the already mentioned valve not being perfect). I did mine with a replacement from Audi (yes I got a better price from the audi dealer and a metal one way fuel check valve off ebay. best to replace all the light blue pipes in one go as they will all be p00p. after them the suction jet pump is a good candidate for leaking boost but its a PITA to change

OK the language filter likes p00p

Anyone know the part number? Thanks .

The most common pipe to split around the inlet manifold is the S pipe which does from the T piece PCV to the underside of the inlet manifold. Your photo with the arrow would suggest to me that your problem is the S pipe.

I think that's it looking at the diagram, however if I'm doing one and the cost is reasonable, I'll just do that whole lot.

It looks like that S pipe but, basically the two pipes at the bottom of the manifold it's the little pipe on the right? It looks like that's the S pipe yes?