I have started this thread and hopefuly this will make things easier when you get the Common "Mk3 running issues!" The list is quite long and every car will behave differently and even 2 cars with similar issues will have 2 different faults! (hence why no "my car is stalling" info)...
So if your car has the common engine running issues...read this thread.
Hopefully this will help people locate and fix thing's when the problem's start but the common fault's seem to be
1
dirty throttle body Lumpy idle/Stalling at idle
Buy some carb cleaner for around a fiver. If it isnt 100% clean this is well worth doing and solves many idle/stalling issues.
2
faulty ecu relay no 30 rough running
Both the 8v and 16v have the same #30 ECU The #30 relay part # is 165 906 381
Check them by feeling how hot they are after 15 minutes of driving. they should be warm to touch. so cold relays means faulty relays!
3
faulty fuel pump relay no167 rough running
Make sure you get a light grey/brown coloured one with 'made in germany' on it and it comes brand new in a vag box. The originals were made in Tunisia and are a known issue!!
4
hall sender 5000rpm limit
Fixed to the side of the dizzy and also stops the engine reving over 5000rpm. Should show on vag-com as an error but its also worth checking the wires as these get brittle and break with age!
5
Crank angle sensor/engine speed sensor/pulse sensor Cutting out/oil light flashes
The part # for the 'crank angle sensor' is...037 906 433 and is the same for 8 or 16v cars, You can buy non-vag, the brand is called 'FACET' (made in italy) Its the same part with the same # on the box and a bit cheaper too
Fitting: you need to remove the front engine mount bracket so need at least 2 jacks. one to lift the car and the other to support the engine while the bracket is out. The sensor is behind this bracket and is held in by an allen key which is likely to round.the engine mount bracket has the flippin starter motor attached The bolts go through the starter motor and into the bracket.
6
ecu temp sensor stalling only when hot/cold
When starting from warm the car behaves as it's running with the choke out, the rev's are too high and often don't want to settle below 2500rpm and this controls the fuelling and when faulty it makes the mixture richer (as the engine believes its still cold). this also works the other way..stalling when cold but ok when warm.
7.
Oil breathers rough idle/running
split or gunked up breathers can make problems... As the youngest mk3 is now 10 years old these are starting to show there age. You can remove the pipes and check for blockages or even hear a whistle when split.
clean them using petrol etc or get new oil breather pipe (and other vacuum pipes)
8.
cam belt and 5000rpm limit and recently had new cambelt
If this is fitted one notch out it stops the car reving above 5000rpm as the engine goes into safe mode..and can also give flat spots and idle issues!
Fixing: The engine timing belt needs to be removed and refitted, It could be wise to get a timing light to check as its not the easyest of jobs!!
9.
Coil Stalling when wet/damp
This will normally show itself when its damp or wet and makes starting hard or the engine cut out!! There is no fix for this, so a new one will be needed. the only way to see if its the coil is look at the coil when dark and you may see it sparking! Or when the car cuts out, miss fires etc spray some wd40 aroung the coil and if it runs better..thats your culprit..
10.
Car stalls/wont start but wiggle the key and it's back to lifeThis means a faulty ignition switch... The part is cheap but it does mean taking the wheel off to replace. On later cars you cant simply replace the whole unit as the key is coded to the ecu. Early cars are much more simple without either airbag or immobiliser
I will update this thread with pictures etc and other info that is relevant....please pm me any pictures,fitting tips or otherwise and the thread will be ammended!
