rough idle on cold start

[Smudgerii]

Car has been suffering from rough idle on cold start for the last week, so into Lightcliffe Warrington today for a check up.

 

Have the car back and a report of all Coil packs ok, no codes just "sooty" plugs.  Question is, why are they sooted up?  It get Tesco 99 on every fill up, just had 20k service before issue arose and is driven failry hard .

 

Any ideas?

[Ootohere]

is your car a CTHE or a CAVE?

 

If a CAVE have the put the latest ECU update on it?

 

What did they do then, clean the plugs, Inspect them and put them back in.

I would have paid them £40 and had new ones put in since they had all 4 out.   ?? Did they have all 4 Spark Plugs out, or just 2 ?

 

Since that Dealer you use says they have fitted 7 Engines this year,

i hope it has nothing to do with their Diagnostics & Spark Plug checking skills.

[MattGreen]

I'd ask for a compression test.

[Smudgerii]

It's a cave, and yes all out for inspection and clean up. 

 

Left the car there overnight and all done by the time I phoned to check if car ready at 16:00, they know I work nights so they won't call me to ask if I want any other jobs done.  so far I'm happy with the tech guys and how they have handled things, and the car runs strong..

 

Consumption test will be complete monday 7th, so hopefully I will have finished with all the hassle.

 

Not sure why I would need a compression test?

[Ootohere]

Because you are having an Oil Consumption Test, and i take it a Breather Pipe/Valve Modification, and ECU update to see if your engine uses oil.

Well that is the part Diagnosis. & the Conformation that there is Component Failures..

 

The Compression Test would be worthwhile to see if the Loss of Compression is there in a Cylinder & that is why the Engines fail.

 

But Skoda/VW know why they fail really, which is how they knew how to Revise the Engines & Build the CTHE Engines.

so really it is Volkswagen & Skoda Kiddology going on.

 

Considering they have Hundreds of 1.4 TSI Twincharger CAVE engines removed from cars in different World Regions

They have plenty to have Experts Examine, Inspect & find every possible reason for failures,

How can the Worlds Second Biggest Car Producers not know what is wrong with their Design & Manufacturing.

[Smudgerii]

Yes the breather mod was done at the start of the consumption test.  I'll ask about the ECU updates on Monday.

 

I knew of the issues with these cars before buying, so went in with my eyes open...

[Jabozuma]

Was your car heavy oil guzzler? Would assume so reading about oil consumption tests...

Your misfires only on cold starts or you noticed them at other times as well?

Let us know how it went.

BTW, "sooty plugs" are normal and in itself such a statement means nothing. Healthy plug should be sooty a little bit on the rim. What is important is how the rest of the plug looks like, and all of them, not just one, like George wrote.

Compression test would tell you if your engine has a serious problem. This could save all other investigations/oil consumption tests. If no compression no point in doing anything else - new motor as they will not be able to first of all diagnose what is wrong and then repair it. Cheaper for them to get new motor.

[Smudgerii]

no miss fire any other time.  It drinks a bit, but maybe the brether mod will ease this, won't hold my breath...

 

Didn't see the plugs myself so going to have to believe the tech.

[Smudgerii]

Quick update. Finished work at 04:30 start car and miss fire as bad as ever :(

Back on the phone later today...

[Ally_bassman]

How bad is the misfire?

I have a CAVE engined car and I have noticed that I have a misfire when cold since I had my plugs changed to the revised spark plugs during my cars last service. At Lightcliffe Warrington incidentally!

I find a slight vibration when I start up and upon first pulling away the car sounds rough until it reaches 2k rpm and then smooths out. No other problems or misfires and my car uses some oil too. Around 1L per 2k miles.

[MattGreen]

Not sure why I would need a compression test?

Because I am in the process of getting this sorted with Skoda and the only test they've run so far that showed something wasn't right was a compression test. If there's a problem with piston rings or valves a compression test should show it.

I have a good 350 miles left of an oil consumption test before I go back in.

[Jabozuma]

We need to remember that first of all twinchargers, and probably other TSI motors as well, have double injectors duty on start-up to heat the cat as fast as possible due to emissions laws.

Then it runs retarded as well - I checked my logs and it can run yp to -20 degrees retardation!!! 

To check if you have a problem simply switch on for 5 secs, switch off then straight away switch back on. ECU remebers the first start and deosn't do the usual retardation/double injectors duty routine any more and car runs smoothly. This tells you you do not have a problem.

If it misfires any other time then you deffo need to investigate

 

 

How bad is the misfire?

I have a CAVE engined car and I have noticed that I have a misfire when cold since I had my plugs changed to the revised spark plugs during my cars last service. At Lightcliffe Warrington incidentally!

I find a slight vibration when I start up and upon first pulling away the car sounds rough until it reaches 2k rpm and then smooths out. No other problems or misfires and my car uses some oil too. Around 1L per 2k miles.

Do you have part numbers for those revised plugs?

[Ally_bassman]

I certainly do! 03C905601B

[Jabozuma]

I certainly do! 03C905601B

Thanks

[Smudgerii]

We need to remember that first of all twinchargers, and probably other TSI motors as well, have double injectors duty on start-up to heat the cat as fast as possible due to emissions laws.

Then it runs retarded as well - I checked my logs and it can run yp to -20 degrees retardation!!! 

To check if you have a problem simply switch on for 5 secs, switch off then straight away switch back on. ECU remebers the first start and deosn't do the usual retardation/double injectors duty routine any more and car runs smoothly. This tells you you do not have a problem.

If it misfires any other time then you deffo need to investigate

 

 

Do you have part numbers for those revised plugs?

 

Will give this a go..

[Smudgerii]

We need to remember that first of all twinchargers, and probably other TSI motors as well, have double injectors duty on start-up to heat the cat as fast as possible due to emissions laws.

Then it runs retarded as well - I checked my logs and it can run yp to -20 degrees retardation!!! 

To check if you have a problem simply switch on for 5 secs, switch off then straight away switch back on. ECU remebers the first start and deosn't do the usual retardation/double injectors duty routine any more and car runs smoothly. This tells you you do not have a problem.

If it misfires any other time then you deffo need to investigate

 

 

Do you have part numbers for those revised plugs?

Well tried it, on for 5 secs then off and no misfire on second start up...

[Jabozuma]

Yup, same as my experience. I just think this chase for emissions is sometimes proving a bit too much for the poor old internal combustion process.

That aside I understand that a change in spark plugs occured not so long ago. It was to do with electrode gaping being too wide thus causing misfires. Originally it was 0.9-0.95mm and now is 0.8mm. People tried down to 0.7 and were really happy with results. Some even said that due to proved smoothness torque sensor readings effected smoothnesss of DSG operation:)

[Jabozuma]

In theory the wider the gap the bettet as the initial flame front is bigger and air/fuel mixture burns better, more homogeneous I.e more power from the same amount of mixture. As good as it is at low revs it is starting to fail at high revs were frequency of ignition event increases-ignition system struggles to supply enough juice on time. One can either narrow the gap or beef up the ignition system.