1.4 16v hunting for tickover

[tag1_uk]

Hi Guys,

I've got the dreaded AUB code 1.4 16v engine, still the original piston rings to the best of my knowledge. A bit excessive oil consumption - I estimate that the oil level would go from maximum to minimum on the dipstick in 500 - 600 miles. At high rpm it pulls fine but below 2000 rpm it is a bit of a tank although I appreciate that this car doesn't have the best throttle response around so I don't know how much this is normal or how much it is to do with dodgy piston rings.

Anyway I've previously reported that very occasionally the car wouldn't tick over that well with it "hunting" for a stable tickover fairly vigorously by +/- 500 rpm or more. This was a really rare occasion and seems to be fairly common for this engine so I wasn't too worried. Anyhow, possibly tied in with the suddenly warm weather, this fault seems to suddenly be a lot more common, happening at least once per trip over the past week (but most other times during the same trip the tickover seems fine with just a slow wander by +/- 100 rpm). It seems to settle down with a dab or two to the throttle but sometimes doesn't settle down so well until I've pulled off and travelled some distance before stopping again (I'm talking about town driving). Should I be concerned? I'll need to have a look at the air filter and associated breather hoses for oil I think. Any merits in a bit of redex or such like in the fuel (I can't afford to be putting in V Power all the time)? Nearly forgot to mention - no sign of any warning lights on the dashboard.

Cheers for advice.

[ExAudiSi]

Might be worthwhile replacing the temperature sender if it hasn't been changed already. They are well known for failing and can make the ECU think that the engine is colder than it really is.

I would definitely check the breather on the back of the air filter first though, with the cold weather it can get full of emulsified oil which will block it up and can also increase oil consumption. Mine seemed to run better after I'd cleaned this out.

[isinglass]

Like you say I would pull off the engine cover and see how mucky it is and give it a clean up. It's probably the throttle body is dirty.

Oil vapour get's blown up the breather from the crankcase (this is under the bottom of the pistons). You get this anyway to some extent as the crankcase is under positive pressure somehow this reduces emissions. Too much crankcase pressure is bad for piston rings though hence don't overfill the oil.

This vapour can be worse if the piston rings are worn as you also get blow past the pistons as the mixture lights. This sends more stuff up the breather.

There is a oil filter thing in the air filter housing this looks like it's supposed to stop most of it. It's in a leaky pipe thing. Oil seems to seep out of this and along the pipe, round the air filter rubber and also drip into the throttle body.

Does anyone know the part number of the oil filter bit in the engine cover? It's held by a rivet but I would quite like to change it as I would like to see how long it takes to get sodden.

The engine cover just pulls off. Theres 4 mounts that fit in rubber holes on the bottom of the engine cover. Give it a pull from the front first and then the back. Theres a rubber pipe on the back left of the cover too (the crankcase breather). Pull it off.

Use a philips screwdriver and lossen the 11 numbered screws. The air filter is under that cover. Clean the housing and change the filter.

Have a look at the throttle body and clean it very carefully with a little wynns fuel injection intake cleaner and a lint free cloth. I presume the jumping about is the car trying to make subtle adjustments to the little butterfly valve but it's a bit gummed up?

I still don't know what causes the rings to go though. Like audisi says the breather is apparently prone to blockage? Does this lead to too much crankcase pressure? Also people seem to report better running on super unleaded higher octane, preignition damage? Perhaps short journeys lead to too much moisture in the engine causing condensation and emulsion blocking the breather?

[Mr Brum]

Throttle body, or a cracked hose leading from it.. (my Cupra used to do it )

good luck in getting it sorted

[tag1_uk]

Hi guys,

An update - I've finally managed to get the engine cover off - the air box between the air filter element and the down pipe into the throttle body was covered in oil, dripping with it really to the point it was seeping around the outside edges (and I guess the inside edges) of the down pipe where it meets the throttle body. There is a wee filter thingy on the breather hose were it enters the engine cover - this was pretty caked up with grot. The valve on the top of the throttle body was reasonably clean on its face but quite dirty around the edges - I didn't like to touch it too much to clean it in case it damaged the alignment settings. Anyway I've given the filter on the breather hose a quick clean but I don't think it has made a lot of difference. I've not done a compression check or looked at the spark plugs yet. Any more ideas whether these are signs of the piston rings problem or whether I should buy a new breather hose/filter assembly and this'll cure it? Any merits in taking it to an independent VW specialist (there's one nearby) to get the throttle body stripped and cleaned and properly reset on the computer?

[cjb]

Originally Posted by tag1_uk

Any merits in taking it to an independent VW specialist (there's one nearby) to get the throttle body stripped and cleaned and properly reset on the computer?

I'd say yes- our Lupo was hunting after the battery got a bit flat, a TB realignment sorted it.

[bobjim]

is there a throttle positioning sensor on it,

my hyundai coupe used to do it, cheap to fix and that used to do the same??????