Odd starting problems and oil burn

[Tehtog]

I have a 2005 MK1 Fabia 1.2 HTP 6V, almost 100k miles and it's had the following odd behaviors:

 

• Burns about 500ml of oil every 1000miles or so - It's not leaking
• Sometimes it doesn't start first try, switching it off and on again lets it start
• Sometimes when it starts it sounds rough and feels like it's hitting the rev limited at 4000rpm instead of near 5-6000 as usual, Almost like a misfire. Restarting the car fixes this too.

 

The yellow engine/exhaust system light came on and the car read the following fault codes:

• 16804 -  Catalyst System; Bank 1: Efficiency Below Threshold
• 16556 - System Too Rich, Bank 1
• 16725 - Camshaft Position Sensor (G40): Implausible Signal

 

I had the timing chain and this sensor replaced and the problem went away for a few months but now it's happened again, exact same light and same codes. I didn't drive for a week and the light went away.

 

 

 

I'm not overly gifted mechanically (I can do the basics). Any ideas on what's wrong and what'll cost me to fix?

edit: I should note, Car's due a full service soon if that's related?

Edited 1 May, 2015 by Tehtog

[hutchysrs50]

Sounds similar to my problems.

I'd say your valve guides have worn, letting oil into the engine and burning it inside.

Due to the oil burning your cat is slowly becoming blocked.

[Tehtog]

Sounds similar to my problems.

I'd say your valve guides have worn, letting oil into the engine and burning it inside.

Due to the oil burning your cat is slowly becoming blocked.

 

I'm confused as to how restarting the car cures all these issues. Wouldn't it be gradually worse?

 

Assuming valve guides are worn how much is a repair likely to me. I'm thinking of trading in for a new fabia or a polo so was hoping to resolve all the issues first.

 

edit: Just to add I'm getting 40mpg average and there's been no huge change since i got the car.

Edited 1 May, 2015 by Tehtog

[hutchysrs50]

It's just my thoughts on the problem. Could be an iffy egr valve or something.

First thing I would do is a compression check and go from there.

Expect around £600 if your wanting the valves and valve guides replaced.

[Breezy_Pete]

Not going to be an EGR problem, the 6-valvers don't have one, I don't think.

Compression test sounds like a fine idea to me, especially as it sounds like you drive this engine quite 'enthusiastically'. There's no more power at all above 4k, if you look at the performance plots, so redlining it is of questionable value.

[Tehtog]

Compression test sounds like a fine idea to me, especially as it sounds like you drive this engine quite 'enthusiastically'.

I don't, I was just describing the mode the car goes into where it is down on power and doesn't rev very far. It's currently with the mechanic so I might know soon. It has us both stumped.