Hi All


My wife's 1.8T AUM with auto box has a weak/low idle. It doesn't stall but does drop down to 550rpm after the engine has warmed up when stopping at lights, roundabouts etc. If the engine is warm and you start her up she sits nicely at 800rpm but as soon as you select D or R on the auto box she drops down to 680rpm and until she is restarted she never idles at 800rpm again. Also (I think) linked to this is: when going from P or N to D or R when cold (rpm1000-1100) it does the gear change as expected in an instant but when the engine has warmed up and the Idle is low selecting the gears takes a few seconds more than it should. All automatic gear changes as you are driving along are fine, it’s only when manually selecting the gears at idle. I have VAG COM but I'm no pro with it, all error codes have been fixed.


Things I've done to the car since purchase:


New standard plugs, coil packs 2L upgrade, rewired coil loom

New Bosch MAF supplied by ecp
Cleaned and reset throttle body + AIT sensor

Installed oil catch can and changed all vac lines
Cleaned inter cooler and hoses

New thermostat and temp switch

New brake servo and vac lines

Auto box soft coding as it was in factory mode and not sport mode

ABS gyro sensors and soft coding as there wasn’t a code in it

New blow off valve

Repaired not removed leaking secondary air injection system

Serviced and cambelt was replaced a couple of month before I purchased it


I’m sure I’ve forgotten some things off of the list, all this work has improved the running/smoothness/MPG of the engine but it hasn’t solved the idle issue. I’d like to check the soft coding for the engine ECU as the other 2 were wrong but I can’t find any info out on this and any other suggestion/help would be much appreciated.


Thanks for your time.


Yours Dave