Smoky, smelly and slow.

[ollygti]

Hi.  I was stuck in traffic the other day in hot weather.  I noticed the exhaust note change (sounded like it had a hole in) and then  blueish smoke from the exhaust!!!  It started running rough and had no power, smoothed out a bit on the way home and the smoke seemed to clear but still down on power    The exhaust still sounds weird and smells of fuel.  Oil and water seem fine.  Its an 8v GTi digi. Please Help.   

[danny_p]

compression test calling

[Wayne]

As above, carry out a compression test.

[ollygti]

Thanks for the advice. Should I avoid driving it?

[danny_p]

thats probably wise.

the symptoms you list chould indicate a very big gremlin is about to mature and come out of hideing.   

the rough running and noise you describe allong with the lack of power suggest that for some reason it's stoped fireing on a cylinder.

untill you investigate it's hard to tell what it would be, it chould be just a sparkplug or HT lead  but it chould equaly be somethign much more serious

[ollygti]

Oh great    Thanks for the advice.  Thats what it feels like when driving.  I checked the plugs and leads yesterday. They look ok visually.  Dizzy cap looks ok too.  What could stop one of the cylinders firing assuming the plugs are producing a spark? a blocked injector?

[weazgti]

This thread has me worried now. my 8v has done this when its been idling for ages and i ve switched it off and tried to restart also when i had the car on a ramp the other week it filled the garage with smoke and was gutless for a bit afterwards.
My valve stem seals are shot but i ve been driving it for a while and i even managed 350 mile round trip to santa pod last week and it was fine apart from using a bit of oil.
I was hoping it was just valve stem seals.

[danny_p]

that chould just be valve stem seals.

if your sparks are fine it chould be an injector gone down ( or more likely the wires to it ) or that cyl has lost compression.

you chould try running it with a plug lead off 1 cyl then the next,   if on any cyl it dosent change the way the engine runs compared to when all 4 are connected you have found where the problem is.

chould be a plug given up ( rare but it dose happen )
choudl be an injector ( also rare but it dose happen )
infact it chould be meany things once you have done a CR test all will be much clearer

to stop a cyl fireing it's  ether got no fuel, no spark or no compression

[ollygti]

Thanks for the info.  Ok I'm a bit confused.  Checked compression and all four are at about 190psi +/-5. Listened to the injectors (with a screwdriver!) and they are clicking away ok.  Removed HT leads one at a time and it ran worse each time so i guess all cylinders are firing. It still sounds like the exhaust is blowing when it revs and it defo gets worse when its hot.  Don't know what temp its running at because the computer(and rev counter) not working. Also cleaned pcv and checked for vacume leaks all seem fine. What do i check next?

[danny_p]

so you have good compression on all 4,   it's fireing on all 4.  but it's not happy.

i would be tempted to pull injectors out and see if they are all squirting evenly