Thought some might find this interesting ?
Discussion
This car was poodling (1300-1700rpm) along & when it startred to misfire plus the engine light started flashing .
3 weeks before it had a full service, all new plugs then an MOT which it passed no advisories .
Scanned it, it showed misfire on 4 & Cyl 4 had been shutdown by ECU? OK , so out come the plugs & this is No 4 plug ,all the rest are perfect.
Hmm ?, the porcelain that chipped off was lodged in the electrode, I then did a compression check, 1-2-3 all good in & within spec Zero compression on No:4 Cyl, put a boroscope down, pistons all OK . The injectors are still functioning so when the driver door is opened it primes them, the piston on No:4 is a lot wetter(?) than the rest?
So struggled to get the boroscope to look up towards the valves & when I did ...well look at this ...I'm thinking a injector but if not that ?
3 weeks before it had a full service, all new plugs then an MOT which it passed no advisories .
Scanned it, it showed misfire on 4 & Cyl 4 had been shutdown by ECU? OK , so out come the plugs & this is No 4 plug ,all the rest are perfect.
Hmm ?, the porcelain that chipped off was lodged in the electrode, I then did a compression check, 1-2-3 all good in & within spec Zero compression on No:4 Cyl, put a boroscope down, pistons all OK . The injectors are still functioning so when the driver door is opened it primes them, the piston on No:4 is a lot wetter(?) than the rest?
So struggled to get the boroscope to look up towards the valves & when I did ...well look at this ...I'm thinking a injector but if not that ?
You are tyre tread, it made my eyes pop open!
Its only one valve showing ,what you are looking at Chris32 is the Plug hole & the boroscope camera lead . Its a bit more than a crack in the valve Chris, about a 3rd of the valve head is missing! I think it must have hit the spark plug hence the missing porcelain shroud
Its only one valve showing ,what you are looking at Chris32 is the Plug hole & the boroscope camera lead . Its a bit more than a crack in the valve Chris, about a 3rd of the valve head is missing! I think it must have hit the spark plug hence the missing porcelain shroud
Tyre Tread: Apparently it was running fine , had just had a run of 20+ miles to a bank, parked then 5 minutes down the road @ 1250 rpm ish was told they were in a 40mph area going 27mph car close behind so pushed up to 35mph then pop pop misfiring etc? ( no t my car Audi 2.0 TFSI 2013 45000 MILES.
BUT it had been Serviced & Mot 3 weeks prior & that was the 1st trip out since then, before that it had not been used or started in 4 months!!
Evo: its a family memeber (Sis) so she'll buy the parts I do Brotherly love!
Tyre tread: I will post up the photos when I get around to it but thats the thing. I have just moved in fact received the contract to sign yesterday , so I have to demolish an existing garage then build my own ..sis is fine with that & I have given her a Seat arosa 1.0 to use until then...
here is the piston though.
BUT it had been Serviced & Mot 3 weeks prior & that was the 1st trip out since then, before that it had not been used or started in 4 months!!
Evo: its a family memeber (Sis) so she'll buy the parts I do Brotherly love!
Tyre tread: I will post up the photos when I get around to it but thats the thing. I have just moved in fact received the contract to sign yesterday , so I have to demolish an existing garage then build my own ..sis is fine with that & I have given her a Seat arosa 1.0 to use until then...
here is the piston though.
Tyre Tread said:
oakdale said:
Check the fuel, that could be the result of diesel in the tank.
What, the missing half of a valve caused by diesel? How?Diesel fuel has a high cetane rating which means compression and temperature rise will cause it to self ignite, on a diesel engine the ignition point is controlled by the fuel being injected directly into the cylinder at exactly the right time but on a petrol engine, the fuel air mixture is in the cylinder at the start of the compression stroke.
This can cause a vicious cycle of detonation and pre ignition well before the piston gets to the normal ignition point, the extremely high temperatures caused by this will melt a valve like a blowtorch, when the valve opens and is off its seat, there is nowhere to dissipate the heat to.
AW111 said:
I managed this due to excessive detonation :
Ooh nasty, was it a weak mixture Or timing ?I have a sneaking suspicion this is a clogged injector which would also cause a lean/weak mixture & detonation I guess...Apparently (not sure) these engines have had issues with the injectors as they have brought out updated injectors . Also its a Direct injection as opposed to port injection & they also can suffer from quite bad carbon build up.
I had to squirt in some DPF cleaner & carb cleaner to be able to see the top of piston clearly for cracks or chips etc , the others are quite black carbon as well. Anyway we'll only know when it comes apart & I am expecting to find piston damage, as yet another possible fault with these blasted engines appears to be that the pistons have a weakness in the land area. The alloy breaks up between the top & middle rings . It may look fine on a camera but once taken out its a mess....but I think this may have missed that as all the research so far suggests it was between 2011 & early 2012 so she may be lucky.
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