Hi, I have a 20 year old Skoda Octy.  the 1.8t but not the VRS model. 

It has recently started being difficult to start from cold requiring 3-4 attempts of rattling and coughing before purring into life -but once warm it was fine and seemed to be driving OK... That was until yesterday when It decided it didn't like warm starts either and started idling erratically.  

I cleaned the throttle body up a bit (I didn't remove it just a spray and wipe round the inside and on the valve (I used TB cleaner) I also took off the top of the airbox and checked all the electrical plugs on it were were visually in good condition and plugged in properly I gave the rubber pipes a visual inspection and made sure they were on properly -the car still displays same behaviour.   I did some poking about on the internet and read that there are many issues that could cause these symptoms including the MAF sensor so I gave it a visual inspection and sprayed a little contact cleaner on just in case there was oily residue on it or some other gunk but the issue still persists.   next I tried (just for the heck of it) unplugging the battery and leaving it for half hour then reconnecting it, I thought a re-boot might make a difference but it didn't.  

 

It's probably time I stopped blindly buggering about with it and see of perhaps some if some of you knowledgeable people might make a educated guess at advising me on what my next step might be?

 

Cheers.

Edited 3 February, 20197 yr by Blueb4sunrise

My first thought would be ignition coils giving an issue. Have you had the car scanned for codes yet at all?.

35 minutes ago, kentphil1 said:

My first thought would be ignition coils giving an issue. Have you had the car scanned for codes yet at all?.

Thanks for your quick response. 

I have not had codes pulled yet, I have a friend who is going to bring over a VAG com in the next day or two which will hopefully help with that. 

I will report back with codes. 

At 20 years old it is probably suffering from vacuum leaks from the CCV system which doesn't help idle. A smoke test would be a good idea.

 

If you suspect the MAF try running with it unplugged and if it runs better its probably in need of replacement

 

A good clean of the throttle body can sometimes help if the idle is a bit lumpy. Depending on which 1.8t engine code you have, you can reset the throttle body adaptations by making sure the car is flat cold (first thing in a morning) turning on the ignition without starting or touching the accelerator and if you wait 3 minutes you will hear the throttle body moving about and re-calibrating. This worked on my 2003 TT but earlier 1.8ts still had a throttle cable I think in which case this is not applicable

 

The wiring loom for the coil packs can also get in a bad way, the heat makes the insulation crack and peel off so that loom is worth a check.

Edited 3 February, 20197 yr by SuperbTWM

1 hour ago, SuperbTWM said:

At 20 years old it is probably suffering from vacuum leaks from the CCV system which doesn't help idle. A smoke test would be a good idea.

 

If you suspect the MAF try running with it unplugged and if it runs better its probably in need of replacement

 

A good clean of the throttle body can sometimes help if the idle is a bit lumpy. Depending on which 1.8t engine code you have, you can reset the throttle body adaptations by making sure the car is flat cold (first thing in a morning) turning on the ignition without starting or touching the accelerator and if you wait 3 minutes you will hear the throttle body moving about and re-calibrating. This worked on my 2003 TT but earlier 1.8ts still had a throttle cable I think in which case this is not applicable

 

The wiring loom for the coil packs can also get in a bad way, the heat makes the insulation crack and peel off so that loom is worth a check.

You have just jogged my memory by mentioning the CCV system... I didn't think much about it at the time but my dipstick holder spout cracked and broke shortly before the starting problems began.   Would this affect crank case pressure?  

Edited 3 February, 20197 yr by Blueb4sunrise

Yes, you basically have a good amount of un-metered air getting into the engine via the crank-case which is making it run lean. Get a new dipstick and see if it helps

I ordered a dipstick and guide spout from eBay.  I will still go ahead and get the VAGCOM on it and see if there are any other niggles. 

 

Thanks for your helpful comments.

Out with the old and in with the new dipstick assembly. 

 

It needed fixing anyway but it didn't help the situation.  

 

There is however a development - I drove for 5 or 6 mins and parked, I don't know what possessed me but my pal never got back in touch with the code scanner so I just figured I could just unplug a sensor and see what happens (I seriously doubt this the recommended method) but I figure if you unplug a sensor the engine will either get upset or cut out.

First one I unplugged was the MAF and guess what ... the engine started to sound happier so I went and switched the engine off and on again, it started first time and drove across town and home again faultlessly with no obvious issues or weak/hesitant acceleration nor did it threaten to cut out while idling.  After arriving back home I turned the engine off and then started it again and it instantly jumped into life without issue. 

 

I am going to assume that my MAF has failed and is being a **** and is sending all sorts of whacky info to the ECU.    Or am I jumping to conclusions and the problem could be more complex. 

 

I haven't driven on the open road with the MAF unplugged nor have I tried a cold start.  

 

Any thoughts? 

Edited 7 February, 20197 yr by Blueb4sunrise

@Blueb4sunrise - Your last is a classic way of testing a MAF without a code reader, and your conclusion is almost certainly correct.

When you disconnect the MAF, the result is it allows the ECU to fall back onto a set of stored basic fuel trim maps that are generic and relatively straightforward, rather than reading a "real time" set of sensor readings and creating a finer tuned fuel map.

 

For the purposes of elimination or a failure on the road, what you have done is ok.

7 hours ago, Blueb4sunrise said:

so I just figured I could just unplug a sensor and see what happens (I seriously doubt this the recommended method) but I figure if you unplug a sensor the engine will either get upset or cut out.

 

 

 

If only you paid attention and read my post you could of come to this conclusion much sooner 

 

On 03/02/2019 at 20:50, SuperbTWM said:

 

If you suspect the MAF try running with it unplugged and if it runs better its probably in need of replacement

 

18 minutes ago, SuperbTWM said:

If only you paid attention and read my post you could of come to this conclusion much sooner 

 

Ha, you got me there. 

I just skimmed through it and jumped on the thing you said about the ccv.

 

So a belated thank to you for your excellent and admirable advice and for reminding to read things properly.   

 

Update.

 

So, I held off on replacing the MAF until I knew what was going to happen with the MOT. It got through without too much hassle so I ordered up the MAF .... I just went for a general aftermarket one from a popular auction site.  I installed it without issue and first impressions are that the car appears to be back to it's normal happy self again. It sparked strait into life and felt all nice and whizzy to drive again. 

 

So problem solved and the old beastie will live another year.  Thank you team briskoda for the helpful advice .