Audi a4 b5 idle

Asked by Oct 12, 2015 at 02:51 PM about the 1999 Audi A4 1.8T Sedan FWD

Question type: Maintenance & Repair

So yesterday started problem with idle ,
when I'm driving and pressing the clutch it
goes down to ~ 850 rpms and goes then
back to ~ 1500 to 1800 rpms and doesn't
fall down to 850 rpms while I'm not stoped
a car and started to use petrol way to much
,  car is a Audi a4 b5 1.8t 20 v  ,engine code
aeb ,year 1999 , can someone help me

2 Answers


idling issues are usslay one of a few things. Your car lacks power (alternator problems), spark plugs are going bad, the fuel pump or fuel system has stuff in it or is going faulty, A vacuum leak from one of the many vacuum systems vw uses. The evap system may have a leak some where (key point to look Back wheel drivers side has a evap box in behind the plastic, The pipe for it tends to rot out and fall to pieces and requires replacement.)

3 of 3 people found this helpful.

The most common cause of rough idle on Audi and VW engines is either the N80 valve, ignition coils, or spark plugs. If you are mechanically inclined you can replace the N80 valve for about $40 and 45 min of your time. For the other 2 it is about the same amount of time but you need a special tool to remove the ignition coils. The parts run about $12 per spark plug and about $150 for all 4 ignition coils...or a $400-$600 job at a dealer (cost depends on your location).

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