abf digi 3.2-suspected h/g causing bad idle. fixed now back with a vengeance

try this:
disconnect the vac hose to the ecu. what happens? can you see the engine idle like its gonna die?
does it gets REALLY better when connected?
today i replaced the rubber vac hose with a plastic one and guess what? the engine idles really better, the smell of poorly burnt petrol has gone (now its how it should) and the main thing i loved more is the driving feeling, the acceleration and the rev decrease is so smooth and it feels like i got a new car. never thought that the Manifold Absolute Pressure could affect so much really everything. i strongly advise you to check it very attentively.
cheers!

 

did it today again grrrr.
if ecu hose is disconnected it stalls. every time.
its new 3mm id silicone hose on there. what everyone seems to recomend

 

the loom was removed and continuity checked on all wires. came up fine
i still feel it may be the pressure. cant tick it off until new vr pump and filter is fitted.

 

I've swapped fpr and vacuum hoses and it is still doing it. Seems to be running a bit smoother though. I'm starting to loose my patience with this car.

 

still occuring.

if i let it idle from cold, 9 times out of 10 it will give the uber rough idle, wont rev over 3k, and no power. then suddenly, it kicks in and burns the clutch.

yet if i drive straight off its fine.

so lets think about this in a different way.
what would make it do this from cold? wiring would be intermittant, and happen more or less all the time. as would other hardware.

fuel pressure perhaps?

 

Why don't you do some sensor logs in vag com (if you have it) to see if you can see what happens. Not sure what you've changed as I haven't read the whole thread. Seems electrical to me as I had a few hard to trace problems with mine when I had the standard management.
Diagnostics is very poor on the mk3. But cold damp conditions cause lower resistance path to earth if insulation in components/wires are faulty.

 

iv checked on vagcom. no errors thrown up.

can i wiring fault cause this? i mean the main 'on engine' loom is all good as iv repaired all the suspect bits and checked for continuity.

im thinking either power or ground somewhere else. the last time it cam back was when fiddling when changing the clutch. moving allsorts. after fixing my side repeater wiring the problem hasnt been back. thank god.

the loom was originally from a cupra abf. and some alterations had to be done. im leaning towards this. as its literally the last thing, apart from the tank and pumps left

 

still no errors and its happening again.

my ignition switch is worn. could this be causing the hesitation and bad idle? it does seem electrically related

 

all relays changed. i have a vr6 pump set up so il try that after the ignition barrel

 

did you ever identify the problem? got the same problem at the moment.

 

hi mk1tt16v !
i would strongly suggest what RJ has stated: the Crank sensor + wiring! it seems to be one of the most crucial reasons for the bad idling. last week found a ABF with an almost broken in pieces cable near the crank sensor. cheers.