poor fuel econ, engine juddering..?

[eurobenjy]

Hello all,

I just bought a 55 reg Polo 1.2 for my wife, it has 34000 on it. It has full FSH and fairly low miles, so I thought we were safe...

All was fine initially, but lately I've noticed that the motorway fuel economy is poor (about 35mpg), and the engine judders slightly and intermittently on idle.

I checked the fault codes, and the only one it found was 16955, which I'm told is for the brake light switch (the EPC light came on about a week ago, then went off again after a day or two & never came back).

Could it be the sensors or coil packs? Wouldn't these faults would throw a code..?

Could it be the timing chain / tensioner? Wouldn't this give a misfire, and again throw a code.?

Other suggestions I've found sound scary (poor compression in a cylinder, engine on way out).

Would be really grateful if anyone out there has experienced anything similar and could give me a clue..?

Cheers, Ben.

[red6n2]

I had similar problems a while back changed the coil pack which fixed the juddering... The fuel consumption could be lambda sensor failing.

[eurobenjy]

I had similar problems a while back changed the coil pack which fixed the juddering... The fuel consumption could be lambda sensor failing.

Thanks for replying.

Wouldn't those things trigger a fault code, though?

[chris meardon]

Was it a private sale or through a garage? defo would get it back to the seller if possible.

EPC lights never lead to good things...

[red6n2]

The lambda would... The coil pack I'm not sure take the Ht leads off one by one and see if all the ports are sparking, Is there a loss of power ?. Does it feel like it has no pull and does it juddery on harsh acceleration ?.

[eurobenjy]

The lambda would... The coil pack I'm not sure take the Ht leads off one by one and see if all the ports are sparking, Is there a loss of power ?. Does it feel like it has no pull and does it juddery on harsh acceleration ?.

It's certainly not very responsive, but then again it's only a 1.2...

I had a coil go on my 1.4 Golf a while back, and it's definitely obvious when it happens - flashing CEL, engine sounds like a bag of spanners, massive loss of power... The Polo is definitely not that bad. It just judders when idling, making the whole car vibrate, and the fuel econ is not what it should be.

I'm not sure with these pencil coils whether there's an intermediate failure state where they underperform without triggering any warning, or whether they just suddenly pop like a lightbulb.

[eurobenjy]

OK, here's an update, for anyone who has a similar problem.

Took it to a VW specialist in Leeds (Volksworks). They changed the breather valve, which improved it a bit, but not totally.

They also did a compression test, finding 110, 100 , 90 for each of the cylinders. This is officially within the tolerances, but probably enough to make the engine judder when idle, given that there are only 3 cyls.

Will take it in for a full service and throttle body cleaning next week, but it looks like this is just the way it is... Don't think I'll buy another VW after this one.

[red6n2]

It's a shame you have had a bad experience and let that put you off my 6n2 is on 140,000+ miles and still touch wood going very strong some other car makes would have died long ago.

I would suggest you clean the throttle body yourself though it's not hard and will save you some cash to put toward maybe correcting the judder, have you put it through vag com ?. Throttle body may need recalibrating ?.