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JayDemos
01-04-2017, 05:06 AM
Hi, my engine idles somewhat rough when in park or at a red light and goes away when I begin to accelerate. However, I noticed the vibration is most pronounced at around 1100 rpm. Does anyone know if this is indicative of something specific?

The MAF and purge valve have been replaced as well as the engine mounts. I ran an OBD and go no error codes.

Thanks in advance.

My car:

2001 A4 1.8t Quattro
84,000 km

MacFady
01-04-2017, 05:25 AM
Can you clarify, your idle is rough versus your car is rough when idling. In other words your RPMS wander versus your car vibrates when idling, worst at 1100RPM's? If it's the latter, what happens to the vibration when the car is in neutral? If it improves you may want to consider tranny mounts. Another thing you might want to try if it's vibrating is to re-seat the engine mounts by backing off the nuts, running the car through the gears etc. then re-torque (making sure the car is level).

JayDemos
01-04-2017, 05:35 AM
Thanks for the reply.

Sorry, There is somewhat of a rough idle at around 800 rpm when in the car is in Park or when I'm sitting at a red light that goes away when I start to accelerate. But, if I put my foot on the accelerator and rev the engine to 1100 when in park or crawling through traffic the vibration becomes really noticeable. I haven't noticed any difference in neutral at 800 rpm and I haven't yet tried revving the engine to 1100 in neutral.

xbnipx
01-04-2017, 05:55 AM
This is a very common issue with higher mileage a4s. I would check ur engine mounts. If the rubber is cracked u can feel it with ur fingers. On my b8 I had both mounts go at 70k and 80k respectively (Do this when the engine is cold). I think its safe to say that engine mounts are a must have maintenance item since they are made out of rubber and is subjected to a lot of stress and heat. I would check this first if u have no codes. If they are fine then u can start diagnosing more engine related issues such as misfires or intake vacuum leaks


Sent from my iPhone using Audizine mobile app

JayDemos
01-04-2017, 06:05 AM
Thanks for the reply. I already had the engine mounts replaced. I didn't get any misfire codes so I'm thinking it may be the trans mounts.

MacFady
01-04-2017, 07:28 AM
The MAF and purge valve have been replaced as well as the engine mounts. I ran an OBD and go no error codes.

2001 A4 1.8t Quattro
84,000 km


This is a very common issue with higher mileage a4s. I would check ur engine mounts.

Occasionally helpful to read more than the subject line. In terms of mileage, cars averaged less than 3500 miles/yr. and has new mounts.

PsorianoPre99A4
01-04-2017, 09:51 AM
YOUR CPS can cause slight vibration. If you haven't changed you CPS yet, thats probably what it is. faulty coils or plugs can cause the same.

JayDemos
01-04-2017, 10:23 AM
Thanks, I'll add it to the list.

MacFady
01-04-2017, 01:14 PM
Coils will typically throw a code, and I've never had coils start by giving me a problem at idle, they'll usually show an issue while under load first with misfires and flashing CEL. Plugs you can visually inspect if the car is new to you and you don't know how many km's are on them.