idle problems and fuel consumption

20 Jul 2013
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United Kingdom
My Skoda Octavia ambiente 1.6 2001 model has very poor idle problems intermitantly. The rev counter revs up and then drops suddenly un-controllably. It fluctuautes irratically and this is usually associated with high fuel consumption with a great noise. Whenever it revs up (either on motion or in a traffic situation) and I switched off ignition, I find it very very difficult to start the car and this may take up to 10-45mins(or more) to start again with associated fuel smell during consecutive car start. I have cleaned the throttle body by spraying injector/ carb cleaner. When the car engine eventually starts, the exhaust brings out a dusty-smoky and fuel smell with fuel smell which disappears after a little motorway run and the revs get normalized again and at times the irratical fluctuation of high revs continues. I have changed the fuel pump but problem persists.

Please can anyone advise what the problem maybe and how to fix it? Many Thanks in advance
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Ensure the throttle body is clean

Check the EGR (exhaust gas recirculation) valve is not sticking. Tapping it when you cant get the car to start, might help

And keep an open mind about the temperature sensor

You will need to ask your local garage (not main dealer) to plug the car into their scan tool to tell you the fault codes. Most will do this for a fixed price, but ask first. This will help you to go in the correct direction for the cause
Thank you so much for your prompt response. I actually appreciate you Sir. I had my Throttle Position Sensor (TPS) cleaned with carburetor cleaner several occasions. It was suggested by my local repairer that this TPS was the major cause and I had it changed and tested with a friend’s TPS that uses the same model (though it wasn’t certain my friend’s TPS was in good shape as confirmed by him) and the problem persisted.

Please how do I locate EGR and verify if it’s not sticking in order to tap it?

I have once chanced the temperature sensor and the temperature gauges stopped working/reading, so I had to replace it back with the one that I once removed which was thought to be faulty. Now the temperature gauge (from the dashboard) is reading perfectly.

Sir, can the scan detect all fault codes (all errors)?

Whenever this erratic revs comes up very hihg with great noise.

Your further kind response will be highly appreciated.
This shows you what the EGR valve looks like and it will be towards the top of the engine. It connects the exhaust and inlet manifold pipes when opened.

If you look on U-Tube you might find one being changed, if its not in the video link I sent you?

Not all faults will show up, but hopefully there will be something stored to give a guidance to what the problem is. You will be going round in circles (or very lucky) trying to find the fault without the codes.

Not sure about the noise?
Does the engine shake, like a misfire?
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Thank you very much Mr. Mursal.

the link you sent was very helpful because it shows picture of EGR and how to change it.

Meanwhile, I will go ahead and scan my car as highly suggested and give you feedback as soon as possible.

Much appreciated
Thank you very much Mr. Mursal.
I really appreciate your constructive suggestions and supports.
Am so sorry for getting back to you too late. I actually had challenge in finding suitable diagnosis scanner to scan my car type but I eventually got one that scanned today. It was discovered that Coolant Temperature Sensor (Temperature cool start) and Air Flow were faulty and needed to be changed. I need to buy new and original parts as diagonized by the scan.

I will appreciate if you can tell me on how to buy these genuine parts down to Nigeria.

Thanks in anticipation.

Here in the uk i use euro car parts or ebay sellers for sensors etc
Not sure about shipping to nigeria though!
Coolant temperature sensor and maf sensor are very common failures, make sure you buy original spec sensors from someone like bosch.
It is always worth looking on eBay as a lot of genuine motor factors sell on there, including Euro Car Parts, and many of them offer shipping worldwide.
Yes E-Bay will be a good start, though it might be hard to get genuine parts at affordable prices. You might just have to save a shed load of money and buy a cheaper alternative. Just be careful with the cost of postage, especially overseas.

Good to hear you are getting things sorted.
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