Please can someone help...

i have a 2005 1.8t sline and have recently started getting problems when the car idles. the problem is intermitent but will casue the revs to eratically move up and down between 500/600 and 1000 rpm causing the car to shake a bit.

I am also starting to get problems with starting the car and it seems like it doesnt want to start although thankfully it has so far...

I have had the coil packs changed and also tested the battery which was showing 12v whilst off and 14v whilst the engine was running....

 

Just an update, the battery went flat so I replaced it which has solved the starting problem so it looks like the starting and idle problem weren't related.

Now just need to solve the fluctuating idle... It sounds like an air popping noise under the bomnet from the offside, could this be something or am I just imagining things??

Any advice would be greatful

 

You have a vacuum leak somewhere in the intake ( you may or may not hear it)

The easiest way to check for vac leaks is to start the car and let it idle. Then start spraying starter fluid on the intake likes where you think you might have a leak.. If the engines idle increases, you've found your leak.. 90% of the time its a rubber hose that runs into the intake or a hose clamp that needs tightening..