UK-POLOS.NET - THE VW Polo Forum

hi guys, newbie here.

i just got my girlfriend a 2002 1.2 polo. its was running fine until i noticed recently that the idle is dropping slightly to about 700rpm. its causing unwanted vibration through the car. when i acclerate it goes perfectly smooth. i only get this problem when the car has heated up to normal running temperature. i have cleaned the throttle body which was full of black goo it ran slightly better for a short while. can you gus give me a few tips on what i can do myself before i take it too the garage

Replace the temperature sensor mate. The car is infact a MkVI - Mk6 which is a 9n polo, not a MKIV or MK4, which is a 6n

is thet the sensor at the front of the engine? the lamba sensor?

ignore my last post i seen picutres of the temp sensor on this forum

may i ask why you think its the temp sensor and not the throttly body?

Because its happening when the car is hitting idle temperature, which is highly unlikely to be be a TB related problem

thank you very much, i will get straight onto replacingthe sensor

sounds like a plan

AND its one of the most common culprits for idling issues lol.

changed the sensor, still vibrating at idle (running temp) not as bad though. gonna disconnect the battery to reset the ecu. will get back 2moro

well after a day of driving its almost cured it, if i get the vibration its only for a short moment then it straightens itself out. i.e put brake on when going to idle it gives a judder then goes away. still there slightly but alot more pleasant to drive

ok after a bit of futher testing i found its sort of fixed the problem at idle. i find that when i use any electrics at idle i.e the windows and especially the fan the idle drops slightly and the car vibrates very quickly. do you think it might need a better battery or altanator to cope with the electrical draw?

Sounds like the voltage regulator in the alternator may have gone. Get the battery and alternator tested, as either or both may need replacing.

ok checked the battery read 12.5 with engine off, engine it was 14.5 it stayed steady even with revving the engine to 1500rpm. so i guess that pretty much eules out that bit.i have been looking at that vag software can i manually up the rpm slightly with that software?

Battery sounds ok. I think its most likely your alternator. Mine had exactly this problem, and I had to replace the alternator to fix it.