Skoda 1.8T 20v

Year: 2002

Mileage: 69k originally, now on 72k

About two months ago my vehicle starting revving high from a cold start, this is an ongoing issue which has not been resolved. Shortly after, my engine management light appeared on the dash - i took it to my local garage who diagnosed the problem using VAG Com as a fault with the MAF Sensor - not sure what they did exactly but the light disappeared by the time the car was returned to me. About a month later, the light reappeared and this time they said it was the "Lambda Sensor" which was replaced. This again resolved the problem up until today when the light re-appeared.

I am no mechanic, but am I right in assuming that the cold start is linked to the problem with my engine management light? if not, what could the issue be? Any help would be most appreciated.

Edited 1 October, 200817 yr by DGW
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Possible Coolant sensor problem at a very rough guess.

Ever thought your garage is just resetting the light and selling you bits u don't need? reset the light and it can take it a while before it comes back on!

You need to actually get what the fault codes are I think. Also, it would help to know which tune the engine is, and whether or not it's been remapped.

Air temperature sensor in inlet manifold maybe?

My old one was caked in oil residue when I replaced it, maybe your's is broken or really grotty.

Dunno really. Any other symptoms?

Hi,

Thanks for your feedback.

I think I have found the problem, below:

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Tell your tech to check for fuel trim issue in measured value block 32 and try and get the fault code to post on site as well as values in measured block 32 it sounds like fuel trim to lean as the values are being calculated as you drive over long term and they are out hence mil light on.

URL - http://briskoda.net/octavia-i/engine-management-light/75132/

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Does that make sense to anybody?

Basically the fault means that the engine's running too lean, which is potentially good for economy, but bad for passing an MOT, and possibly for making it run hot.

Ok Thanks.

Any idea why it rev's so high on cold starts, Could this be related?

Im taking it to the garage tomorrow, so will keep you posted on what they say.

Significantly high revving on cold starts, unless it's like a throttle blip, might be over-fuelling, or normal. Hard to say when I've only ever driven diesels.

Sure it's not just the Secondary Air Pump? It makes a hell of a racket and revs are up but after a minute or two it quietens down and the revs go back to normal. I usually wait until it's finished the lawn mower impression and then drive off otherwise it's a dog to drive for the first 5 miles or so.

Ask the garage for all the fault codes they produced and the readout then post back with them and someone will be able to work it out

Without the codes, like RichH says, the garage could just be replacing bits but the EML might be due to something completely different.

Could also try a throttle body clean?

Just made the trip to the garage this morning.

The fault code was 17705 (Pressue drop between turbo and throttle valve). Different fault code to previous times. I think it also mentioned fault code 17535.

The mechanic then did a quick check by asking me to rev the car. He had his thumb on the air pipe. Due to the pressure his thumb was pushed back, so he didnt think there was a major leak in turbo pipe.

He reset the light and then said if the light comes back on again, then to come back again as it does not look too serious.

What you reckon?

Time to inspect the emmissions pipework very carefully I think.