2.0 TSI rough idle

[bushfrog]

Around 6 months ago I had an inlet manifold flap Bank 1 stuck error on my scirocco - indicating I think that there is some problems with the inlet manifold flap. At the the time I did not notice any problem and continued to drive around 5000 miles.

Last week however I filled with 95 RON fuel - would usually do 97 (but no always) . Straight away I noticed that on applying some power i lost then regained some power (possibly a misfire)... only occasionally on my 50 mile journey home otherwise a good drive. But since I have had a rough idle sounding like bubbling from the exhaust and you can feel it in the car (very minimal movement of needle if any)

I took it to local VW who checked Coils, all ok.. Then proceeded to replaced inlet manifold (total cost around 800 inc diag parts and fitting ).. They did not seem to think it was the fuel change...

Just got home and still a rough idle and I am convinced it has something to do with the sudden fuel change (aside from the rough idle I think there is a general improvement from having the new inlet manifold).

Anyone else experience a similar problem that could shed some light would be much appreciated.

Car is 2008(58) plate done 75k miles

[neil_mac]

Sounds a bit similar to what i experienced recently. For a while I noticed a small,occasional dip in power then a rough idle. Soon after the epc light is on and diagnostics pointing to throttle body. It could be a bit of crap, dirty fuel etc.....if it keeps happening then it might need investigation. Mine has apparently stopped doing it.....famous last words an all that lol

[shshivji]

Might be worth performing a throttle body reset with vag com.

Shak

[bushfrog]

May look into the throttle body reset if the issue continues on a couple of weeks. Thanks Shak.

I also had a throttle body issue when first buying the car at 50k miles (EPC light intermittent) - I got throttle body replaced and had no other problems. I think the issue was the some liquid/lubricant was leaking from the seal and the side of the throttle body (black plastic bit) causing it to get stuck. Apparently quite common.

I contacted VW today to let them know problem still existing with rough idle.

They claim that rough idle has improved since after I bought it in and got the inlet manifold replaced (It hasn't) and also state:

"All the tests are clear, no misfire evident, no loss of power. He (technician) speculates that there may be some slight damage in the engine from the breakdown of the intake flap that is causing the lumpy running." -

I'm hoping this is not the case and just think it is too much of a co-incidence but we will see.

[bushfrog]

Car has been back in to VW - they actually offered to take in for free this time seeing as problem was not resolved which i'm really happy about.

After doing a fair bit more investigation and testing they checked the spark plugs - one of which was apparently damaged in some way.

There suspicions are that a piece of inlet manifold hit the spark plug and damaged it - this apparently could be what was causing my rough idle. They think they are now cured the problem and will be doing further road tests tomorrow morning. Hopefully the problems are finally resolved and I will be back on the road tomorrow

[shshivji]

Car has been back in to VW - they actually offered to take in for free this time seeing as problem was not resolved which i'm really happy about.

After doing a fair bit more investigation and testing they checked the spark plugs - one of which was apparently damaged in some way.

There suspicions are that a piece of inlet manifold hit the spark plug and damaged it - this apparently could be what was causing my rough idle. They think they are now cured the problem and will be doing further road tests tomorrow morning. Hopefully the problems are finally resolved and I will be back on the road tomorrow

Thanks for the update! Hopefully happy motoring from now on ;-)

Shak

[bushfrog]

Got the car back now - They did more fault finding .. Further misfire was reported on cylinder 1 . They did compression test and checked operation of all injectors which all passed. All coils and all plugs removed - plug one had apparently been hit by piece of inlet manifold causing minor damage to electrode - adjusted and cleaned plug + extensive test and fault rectified.

Have to admit everything seems back to normal now so very happy and will be leaving some positive feedback for the dealer .

[neil_mac]

Sounds a bit similar to what i experienced recently. For a while I noticed a small,occasional dip in power then a rough idle. Soon after the epc light is on and diagnostics pointing to throttle body. It could be a bit of crap, dirty fuel etc.....if it keeps happening then it might need investigation. Mine has apparently stopped doing it.....famous last words an all that lol

Well it did it a lot over the past few days and was just cutting out altogether when I slowed to a stop.
Turns out that when I got my inlet manifold replaced, the guy must have damaged the clip the secures the plug into the throttle body. The plug has eventually,with the engine vibration,worked its way loose and was causing the problems. A couple of cable ties round it to secure it in place and everything is as good as new.

I made a point of asking the guy at dashfixer,glasgow to check the wiring around the throttle body as I had a feeling that was where the problem was coming from. He said it was all fine....obviously didnt bother his arse. Boy at Halfords service centre spotted it immediately during yesterdays major service and tied it up for me.

[shshivji]

Sounds a bit similar to what i experienced recently. For a while I noticed a small,occasional dip in power then a rough idle. Soon after the epc light is on and diagnostics pointing to throttle body. It could be a bit of crap, dirty fuel etc.....if it keeps happening then it might need investigation. Mine has apparently stopped doing it.....famous last words an all that lol

Well it did it a lot over the past few days and was just cutting out altogether when I slowed to a stop.
Turns out that when I got my inlet manifold replaced, the guy must have damaged the clip the secures the plug into the throttle body. The plug has eventually,with the engine vibration,worked its way loose and was causing the problems. A couple of cable ties round it to secure it in place and everything is as good as new.

I made a point of asking the guy at dashfixer,glasgow to check the wiring around the throttle body as I had a feeling that was where the problem was coming from. He said it was all fine....obviously didnt bother his arse. Boy at Halfords service centre spotted it immediately during yesterdays major service and tied it up for me.

Them clips can easily break if you don't undo it properly, who fitted the manifold for you??

Shak

[neil_mac]

Khan Auotos did the manifold

I should say Dashfixer were doing a diagnostic and I was primarily there to see what the problem was with my cooling fan but whilst they were doing that, asked them to have a quick look at the wiring to the throttle body....said it looked fine but obviously he didnt bother.They reckon the control unit for the cooling fan is gone and the whole fan/unit needs replacing as they dnt come separate. Thought it was just a fuse or a relay. Think I might get it checked by another place.