Not starting on all cylinders...

[Alan]

Hi. I have a strange problem with my S6 in that its not starting on all cylinders. I have upgraded to the 1.8 t coils so Im thinking the problem is elsewhere.
The problem clears after about 15 seconds or so, I usually hold the rpm’s at 1500-2000 until it fires on all 5 and it runs fine after that. It pulls perfectly under load and WOT.
Plugs are good and both temperature sensors were just replaced as part of my troubleshooting.
The lambda sensor was changed about 20k ago so that should be ok.
Starts no problem when hot.
I notice some very slight missing and minor variations at tickover, but its got 180k miles up so I have to give some tolerance for that.
Not burning oil and the emissions passed the test recently no problem.
Im thinking worn injectors?
Anyone got any suggestions???

[s2driveruk]

worn or blocked injector(s) Worth getting them serviced and flow checked, not expensive http://injectorcleaning.co.uk/

Cheers
David

[Hammer786]

Have exactly the same problem as you but for me it's slightly milder i.e. I don't have to rev it as eventually it'll fire on all 5. Is injector removal easy? Mines a daily driver as well so assume I'd need a spare set from somewhere.

[s2driveruk]

de-pressurise the fuel system, basically ignition off, battery disonnected, undo the banjo on one end of the fuel rail, rag to hand to soak any dropped fuel as pressure releases.....then do other end, remove the leads to each injector then squarely lift off the rail.

Recover the orings if any left in the IM or fuel rail.

I think mine took about 48-72hrs door to door.

[Bowlerwell]

Nice one David. Did you notice a big improvement?

[s2driveruk]

in reality i dont think mine were so bad but definately smoother and no issues in starting these days or any kind of lumpiness on throttle which i was getting at times. i think on my project thread (Can of worms) the values pre/post cleaning were posted

[GT500]

Cracked head.
Leave overnight then remove No 2 and 3 plug. Water will be looking at you...

Sorry, miles seems to cause it.

[4WheelDrifter]

Check the head gasket. The coolant leaks normally start at the back (cylinder 5) and work forward. It may be that the cylinders have to be flushed before it has a chance of starting.
Worth checking in case it gets worse and you end up with a hydrolocked engine. But lets hope it's something less severe than that.

If you start the engine does the coolant tank immediately pressurise?

[Alan]

Cracked head!! OMG, not what I want to hear...
Is it weldable or scrap in that case???
I will check it later if there is any coolant getting into the cylinders and report back...

Hammer786, removing injectors is fairly easy, take off the covers and there are two cap screws holding on the rail (and the electrical connectors), each injector is just held in by an O ring so its just a matter of wriggling off the whole rail with the 5 injectors attached. The injectors in turn are held onto the rail by a spring clip that slides out and the injector just pulls out.

[QuattroFever]

not funny, recently i've been getting a stumble on starting that clears after a couple of seconds. Hope its not a fr0okin cracked head!!

[Alan]

Pulled the plugs for a look today and liquid in cylinders 3&4, ****!
Wouldnt mind but I did the belts and pump about 2k ago
It does explain why its sipped a little coolant for a while!
Hopefully its just a gasket and not the head but either way a few hours of spannering ahead...
Will keep you posted on the issue when I get the head off..

[s2driveruk]

nightmare, well i suppose at least you have the answer now

[Alan]

Well I got the head off and thankfully no cracks!


0.4 mm skimmed off and 20 valve seals done.
Full leak test too and 2 valves to be lapped as a result.
Waiting for new head bolts and a head set, turbo in great shape, little or no signs or wear
Should end my missfire problem anyway!

[s2_wot]

Well I got the head off and thankfully no cracks!


0.4 mm skimmed off and 20 valve seals done.
Full leak test too and 2 valves to be lapped as a result.
Waiting for new head bolts and a head set, turbo in great shape, little or no signs or wear
Should end my missfire problem anyway!

shiney shiney, where did you go for the skim and rebuild if you don't mind me asking?