High HC digifant emissions

[Diamond Hell]

Non.

http://en.wikipedia.org/wiki/Oxygen_sensor

[clipperjay]

thin layer of platinum and comes in both heated and unheated forms. The planar-style sensor entered the market in 1998 (also pioneered by Robert Bosch GmbH) and significantly reduced the mass of the ceramic sensing element as well as incorporating the heater within the ceramic structure. This resulted in a sensor that both started operating sooner and responded faster.

The sensors only work effectively when heated to approximately 316 °C (600 °F), so most newer lambda probes have heating elements encased in the ceramic that bring the ceramic tip up to temperature quickly. Older probes, without heating elements, would eventually be heated by the exhaust, but there is a time lag between when the engine is started and when the components in the exhaust system come to a thermal equilibrium.

Still think many are heated sensing types after all the ECU interprets the speed and heat variables of the element the result might be a pre set function of amount of oxygen, but oxygen reacts in air temps?

[rubjonny]

can also be caused by car being too lean, my hc were thru the roof due to it being mega lean. what were your HC and CO readings?

[jmsheahan]

Good god, this thread has gone a bit mad since I left 

In regards to the readings like I say unfortunately I do not have a printout which is a very annoying but I'm sure it was tested when up to temp.

Looks like I'm on the right lines with replacing the vacuum lines and ignition components then. If it's running lean and the ignition timing is correct am I right in thinking this points to suspicions of an air leak?

It never cuts out but sometimes it can be a bit temperamental to start, especially when hot but that could be a separate issue. Never overheats, water temps are fine but oil temps can be a tad high. Better not be the headgasket, like I say all of that has just been done.

[Diamond Hell]

Still sounds like the engine temperature sender to me.

[jmsheahan]

Still sounds like the engine temperature sender to me.

Where abouts is that Diamond Hell? Do you mean the blue temp sender for the ECU etc?

Have just replaced the leads, cap and rotor arm. Seems a little smoother but the old ones weren't awful. Cheap things first and all that. I did noticed that one of the vacuum hoses on the airbox looks perished as well as one on the throttle body so these can't be helping. Hopefully the replacements will turn up tomorrow.

[Diamond Hell]

Where abouts is that Diamond Hell? Do you mean the blue temp sender for the ECU etc?

Yes

[jmsheahan]

Where abouts is that Diamond Hell? Do you mean the blue temp sender for the ECU etc?

Yes

Already been replaced recently with a genuine VAG one unfortunately so can rule that one out. No change from the old one.

[jmsheahan]

Replaced all of the vacuum lines this morning. Annoyed at myself for overlooking this job - a few rather perished hoses. Car felt smoother to drive on the test run although I still have a slight exhaust 'bob' although it is better. Quite a bit of fuel vapour on start up but this cleared as well as smelling of fuel quite potently. Car running well on test drive though.

I've exhausted my ideas now, perhaps time to go through the digi tuning guide again as the new lines may have thrown something out, unless anyone else has anything fresh to add?

[jmsheahan]

can also be caused by car being too lean, my hc were thru the roof due to it being mega lean. what were your HC and CO readings?

Sorry to dig up an old thread but I have some proper HC readings now after today's MOT. Car has been off the road for a while so not had a chance to do much with it.

HC: Max 1200ppm   Actual Value: 817ppm.

It's a pass but seeing as it was 70ppm last year something isn't right