Right, yet another issue with my 2006 1.2 skoda fabia classic HTP. 

 

Just went to grab some food after not using the car for 2 days, turned the engine over and the revs went crazy, from 1000+ rpm all the way down to like 500rpm and it was i assume "hunting" but it was making the car rev and un rev. I switched the engine off and tried again, it looked like it was reving low to i put my foot down on the accelerator a bit and it then started to idle okay!

Now to be fair it is cold but the revs were really going mad which makes me think its more than just the cold, the car recently had the 3 valves and guides replaced as it was misfiring and a new ECU (because they diagnosed it wrongly) it's been spluttering at idle since i got it back but members here assured me it was nothing to worry about. 

 

I have also been running petrol cleaner through it as my garage suggested, down to half a bottle now (not that it'd make a difference i guess but worth mentioning)

 

Any suggestions? When the guy came over to look at the spluttering at idle, everything came back okay, even showed me the live data and everything. 

 

I am literally going to give up with this car soon and sell it!

Has the coolant temperature sensor been changed at any point in your struggle? I'm wondering if that may have failed in such a way that the ECU is being 'told' the engine is much colder than it really is, so the ECU is maxing out on enrichment, but because that level of enrichment isn't really called for, the feedback loop between ECU and throttle body is getting its knickers in a knot. Just an idea, not deeply thought through...

 

Give me a shout if you do decide to sell it please; what colour is it?

Here is a photo of the car! http://puu.sh/dVKcb/2b4f4e342e.png

I can't remember the temp sensor being mentioned at all. The car drove fine when i got it running. Spoken to the dealer (again) and I'm expecting someone to come out again and tell me "everything is fine"

 

Highly annoying! It's had so much work on the damn engine! The dealer even said its because the car is cold, i understand a car may get a bit grumpy when starting it cold but it should cause the revs to be changing that much right? It was like I was revving it with my foot..but i wasn't! Event started the car when it was -0.5 and it was fine!

a fuel injector couldn't do this could it? It's been running on fumes overtime i get the car back (they clearly use it as a run around to use my petrol..) so I'm wondering if it's still clogged? It also took longer to start this time than it usually does.

 

If i do sell the car, I shall let you know. It'd be a shame to sell it considering it's had so much done too it now!

It should start quite happily when very cold, without dramas. The only difference I would expect is the starter motor may take a fraction longer to get the engine up to a speed fast enough for it to fire up and run, simply because the oil is so viscous at very low temperatures. I'm talking fractions of a second difference though.

I don't really know what common causes of hunting behaviour might be on these engines, so I couldn't say whether a fuel injector problem is consistent with it, but my gut feeling is no.

 

Looks like a tidy car, what is that, a sort of beige/grey sort of colour? I quite like it.

I think the official name is simply "beige" I personally love the car, super neat inside and out! In all honesty i reckon this motor worked fine until they steam cleaned the engine, removed all the crap that's keeping the car held together! 

Out of curiosity would a clogged throttle body cause this?

Has anyone tried a throttle body clean? Erase learnt values? And then carried out throttle body adaption. Also worth looking at measured values for coolant temperature sensor when engine is cold before starting. The throttle body adaption usually requires doing after a cylinder head overhaul due to the length of time the battery is disconnected as it tends to lose it's basic settings. Good luck

Engine coolant temperature sensor is a very common culprit, also a stuck open EGR valve can mess up the fuelling, finally a gunked up MAP sensor can give these symptoms as well.

Thanks,

 

Right well i tried starting it and it started. Drove to a friends and switched the engine off, about 5 minutes later i went to move the car and the engine hardly started, the ABS light came on for a brief half second then turned off. Something is definitely not right!

Thanks,

 

Right well i tried starting it and it started. Drove to a friends and switched the engine off, about 5 minutes later i went to move the car and the engine hardly started, the ABS light came on for a brief half second then turned off. Something is definitely not right!

 

ABS light is a red herring, definitely sounds like the ECT sensor is reading high causing over-leaning and making it more difficult to start once warm.

Will pass this information on. I have expressed my concern with the engine, the fact it splutters at idle and now this.

More news! Right well the car was perfect when the garage took a look, left it running, drove it around a bit and nothing (sods laws!) However one of them noticed it was idling lower than it should be. They've taken the car back to clean the throttle body, will it can;t hurt i honestly doubt it'll fix anything. I'm going to replace the sensor myself as i don't trust them anymore.