Golf 1.4 TSI Emissions Headache

[Mbeau]

Hopefully this is the right area to post this. I have a 1.4 TSI Golf Mk5. Also know as the twin charger as it has a supercharger and a turbo.

Runs great and returns good MPG. However I cannot get it through emissions on the mot. It has high co2(over 3.5) and low lambda reading.

I have taken plugs out and all look good. Replaced both pre and post cat lambda sensors. Replaced cat with good condition used item. The current one had only done 35,000 miles. Car is up to temp when tested. Replaced all four pecil coils. It has never run so well! The guys at the mot station are good and very helpful.

On live data the coolant temp sensor is showing 90 degrees C. The only thing I am slightly unsure of it the purge Vale reading which is 2.4% on idle and 9% on patrial throttle. From what I have read this should be 0 or 100%

Can any one offer any advice. I am going to replace the coolant temp sensor and purge valve tomorrow. I don't normally admit defeat, but this is beginning to test my patience!

 

[Crybert]

Redex or similar

Hammer it down the motorway before you take it for the mot

 

[Bluebeard]

If you've spent all of that money, replacing all of those not needed parts, surely it would have been more cost effective to take it to VW and have it diagnosed properly?

 

[Mbeau]

What it has cost me in parts is still cheaper than taking it to VW! And unfortunately they generally go through the same fault finding. I have no faults stored.
I will probably need to find someone that can interpret live data better than I can. That is easier said than done.

Unfortunately whatever the problem is it won't be sorted by redex or similar.

It definately needed a post cat sensor. If there is nothing wrong with the cat, I will sell on for what I paid for it.

There is a good deal of satisfaction from fixing the car yourself, but I appriciate there is a point where someone with more exprience and knowledge needs to have a look. It is quite a complex set-up.

 

[Crybert]

What it has cost me in parts is still cheaper than taking it to VW! And unfortunately they generally go through the same fault finding. I have no faults stored.
I will probably need to find someone that can interpret live data better than I can. That is easier said than done.

Unfortunately whatever the problem is it won't be sorted by redex or similar.

You'd be amazed actually. My mums mini wouldn't pass emissions at the mot. The guy gave me a bottle of fuel additive. Said fire that through and take it a drive and don't be gentle. Came back and he tested it and it passed.. its easily the cheapest way forward. Surely worth a bash

 

[Mbeau]

Fair one. I have nothing to loose by giving it a go! Emissions does my head in!

 

[Crybert]

Is the car mapped? Any other previous mots have emissions issues? How long have you owned it?