Rising engine speeds when idle

[Kam]

I get this from time to time with my car and would like to know the cause.

Usually happens as soon as the car has started or soon after car has started.

1. As soon as engines fires up, the revs rise - like the throttle has been bliped and returns to a normal idle speed (1k revs or just below)
2. After engine has been started, the revs will rise above 1k revs like the choke (if a diesel has one) has come on. It settles down after a few seconds.

The fuel economy of the car has also goen down. Anyone any explanations?
Could it be the MAF sensor? Car runs fine ather than the above mentioned anomolies.

Thanks.

 

[muddyboots]

My Ibiza used to do this once in a while, but only on very cold starts (ie a good few degrees below zero...)

 

[Kam]

Does it in all temps and it certainly is not cold right now.

 

[muddyboots]

Maybe a duff temp sensor though ?

Be handy if you had access to vag-com to log the various sensor outputs and see if anything looked amiss.

 

[slick]

Mine does it sometimes, i found its in time with the AC, so guessing where I'm not keeping the charge up on the battery with regular trips, the battery is suffering a little...
Might be worht watching/listening to see if it does it when the fans kick in..

 

[micky 32]

Temp sensor is faulty.

 

[Kam]

Are Temp Sensors easy to replace and would there be other issues if it is the temp sensor?

Thanks.

 

[muddyboots]

Shouldn't bee too difficult, might have to drain/refill some collant depeneding on where it is located.

It could account for the high idle speed and also the poor MPG - the ECU will think the engine is cold and inject more fuel.

 

[Kam]

Shouldn't bee too difficult, might have to drain/refill some collant depeneding on where it is located.

It could account for the high idle speed and also the poor MPG - the ECU will think the engine is cold and inject more fuel.

hmmmm .... worth investigating. Thanks.

 

[micky 32]

Mine is faulty also and i have the exact symptoms. Some times when the engine is luke warm and i start up it revs right up for a second and then settles. Also you might find the glow plug light stay on for ages and your glow plugs wil be activated when the engine is warm.

 

[Kam]

Mine is faulty also and i have the exact symptoms. Some times when the engine is luke warm and i start up it revs right up for a second and then settles. Also you might find the glow plug light stay on for ages and your glow plugs wil be activated when the engine is warm.

Not noticed the glowplugs lighting up yet..... If it is a temp sensor problem, it is intermittent at the moment.

 

[micky 32]

Not noticed the glowplugs lighting up yet..... If it is a temp sensor problem, it is intermittent at the moment.

Mine is intermittent also.

 

[muddyboots]

Scanned a mate's Golf at work recently and found a faulty temp sensor.

When I started googling, I found that temp sensor failures are very common on VAG engines...

 

[Kam]

Anyone any idea where the temp sensor lies in a 130PD engine? Finding the car is smokey (exhaust) as well now. Thanks.