rough running

[markmarky0]

just had this 8v digifant gti for a week now, engine has been running perfectly apart from on the run down changing down intio gears it pops quite alot, def too much, not normal. But last night just as i neared home i put my foot down and as i came to a stop it was idling very rough, and now both idling and when u rev it , it chugs and runs rough. first time i turned it over it didnt even start.
Please help guys !

[mk2bal]

I'd say go through rubjonnys 8v tuning guide, unless you can be more specific to possible faulty components

[Bigdunc]

blue temp sender poss gone, check your idle screw hasnt wound down from vibrations, thats happened to me befor where the screw unwound so i used some thread lock

[markmarky0]

ok well today i went through the guide for tuning up the mixture and setting idle speed/ignition timing and it made no difference at all. Went to work with the car still ran like a bag of s**t lol , got home had another quick look with a torch and found one of the manifold to downpipe studs had worked loose and was sitting on the driveshaft heat shield, so i think ive found the problem and the reason for the very 'subaru impreza' like sound it was giving me on the way home, would this lack of back pressure this far up the exhaust affect the idling and running of the engine ?

Cheers guys

Mark

[Sam]

ok well today i went through the guide for tuning up the mixture and setting idle speed/ignition timing and it made no difference at all. Went to work with the car still ran like a bag of s**t lol , got home had another quick look with a torch and found one of the manifold to downpipe studs had worked loose and was sitting on the driveshaft heat shield, so i think ive found the problem and the reason for the very 'subaru impreza' like sound it was giving me on the way home, would this lack of back pressure this far up the exhaust affect the idling and running of the engine ?

Cheers guys

Mark

This sounds more than likely 

[markmarky0]

ok well update lol

after thinking it could of been the manifold, it wasent ...
found out that the engine is running on 3 cylinders only, so no 4 is not running,
what i guess is that it needs a spark , fuel and air, and ive checked that there is both a spark and fuel getting to the plug
ideas anyone , as i need the car on the road asap.

fuel pressure regulator ?
coil amp ?

Mark