Fast Idling problem

MOZ_LC_TDI

Active Member
Aug 29, 2008
63
1
N.Yorkshire
Hi Guy's,
New to the Forum and Leon Cupra TDI owner ship. 4 weeks ago I moved over from a Mk 3 Golf VR6 to a LC_TDI for various reasons that I won't bore you with but effectively wanted similar performance to the VR6 but with better fuel economy ( does this sound familiar :)).

Anyway I have purchased a 04 plate Leon Cupra TDI with 57K which on the whole I'm happy with.

I bought it from a main stealer so have full Waranty etc. for a year. I have a few niggles that they have already had it in for but have failed to fix, and have seriously failed to impress me as to their lack of competence ( to be fair I did most of my own work on the VR6 for similar reasons in the past).

The main problem that I have that they so far can't fix is this:

Intermittantly ( but a lot of the time, certainly at least once every journey usually many times per trip) when stopping ( i.e at traffic lights ) when I release the accellerator pedal, the revs fall, but only down to 1200 rpm ( not down to a more normal 850 - 900 rpm) a couple of times it has been as high as 1500 rpm and once at 2k rpm but 99% of the time it is 1200 rpm when its n problem mode. The revs will stay there continually ( I hve left it for more than 15mins still doing it) until I either pull away or quickly dab the accellerator pedal ( if i dab it quickly 7 times out of 10 it will drop to the normal 850-900 rpm and be happy). Its as if something is sticking in that position ( throttle position sensor, valve etc?). It also does it on start up quite a lot ( especially when warm) I know there s an automatic choke type function and its normal for it to start up to 1200 rpm but its supposed to drop back down to normal after a few seconds ( not stay there for minutes).

Some of you may think this is a good fault to have as it will avoid the EGR clogging but it is most annoying. The stealers are researching the problem and are going to consult their MASTER TECHNICIAN :)doh:) and even SEAT direct but I don't hold up much hope due to their recent abilities, so i thought I would throw it open to the forum, to see if you guys can suggest anything.

I have done a search and haven't seen anything specifically like this although I think I am going to try the dielectric grease trick in case its a MAF problem ( seems worth doing even if it doesn't help).


If you can elp I would be most grateful.

Kind regards.

MOZ
 
Feb 1, 2007
1,602
1
Nottingham
Even when cold the revs should NOT be at 1200rpm.
Start with the accelerator mounting area and throttle switch as the revs are controlled electronically.
Glynn
 

MOZ_LC_TDI

Active Member
Aug 29, 2008
63
1
N.Yorkshire
Cheers guy's,
My original gut reaction was to do with the accellerator area or position sensor ( I know its a fly by wire rather than throttle cable), as the car doesn't show up any faults. My assumption was that if the position sensor wasonly slightly iffy the ECU wouldn't necessarily know and would just deliver what was demanded, if it thought I was demanding 1200rpm then it would therefore be happy it was doing its job hence no faults logged.

I had read a few postings through the site which also put coolant sensor in to my mind, I assumed this would come up as a fault? but I suppose if it is only slightly on its way out and is giving sensible but incorrect readings then I suppose the car may think its still OK.

When I get it in to the stealers again, am I correct I assume they should be able to see what these sensors are reading on the diagnostics.

i don't have a VAG com (yet) so can't read them myself, but I can at least get them to check.

thanks again,
If anyone else has any ideas, please feel free to add your 2 penneth.

Kind regards.

MOZ
 

Yella Beeza

Now which way?
Jun 4, 2007
497
0
Edinburgh
I have the same problem with my Ibiza TDi FR, see here:-

http://www.seatcupra.net/forums/showthread.php?t=184435

Never got to the bottom of it. It can't be component wear with mine because the car has only done 800 miles! Never did it for the first few hundred miles either. Last time I was out in it, started up to take it out of the garage and it immediately started idling at 1500rpm. Got out, shut the garage door, got back in, and by the time I'd reversed to the end of the drive there was a bit of a judder, and the revs dropped back to normal. Was out in for about an hour, and idled fine.

There was another time when I returned home and it idled about 1500rpm even when warm. I was a bit concerned switching off because how can the turbo possibly cool down properly with it idling at this speed, and won't it still be spinning?

The only thing I've thought is because I don't use the car that much, the battery can become discharged and maybe it idles faster to help charge the battery up. Or the ECU is somehow relearning the idling speed when cold/warm? I've never disconnected the battery though. Other than this, the car drives fine on the move. :confused:
 

MOZ_LC_TDI

Active Member
Aug 29, 2008
63
1
N.Yorkshire
Hi Yella Beeza,
Thanks for the reply, if yours does it again, try blipping the throttle pedal a couple of times quickly. It may not work with yours but with mine the revs drop back to normal ( if it works your Turbo can spool down safely.
Mine is in at the Stealers, they have had it all week. The tgood news is that they can get it to do the symptoms regularly ( which they couldn't the last 2 times it was in). the bad news is thay can't find the fault. they are liaising with seat direct at the moment but it is looking like they are going to change the ECU on monday:confused:.

As long as it gets fixed and I don't have to pay i don't really care ( It hasn't been remapped yet so i won't loose any remapping data). I think the ECU's are around £750 to £850 so if that is the problem I will be pleased that I got them to change it now rather than living with it. It had the problem right from the day I purchased it so they have acknowledged that they sold it to me with the fault and they will pay to fix it .

i will let you know if and what they finally do to fix the problem.

Regards.

Moz
 

Yella Beeza

Now which way?
Jun 4, 2007
497
0
Edinburgh
Thanks Moz. Let us know how things go (I feel an ECU replacement might be a bit dramatic, but if this cures the fault then so be it).

I did try blipping the accelerator pedal when it did it last time when cold, and the revs returned to normal. The symptoms do seem just like you're experiencing though, and difficult for Seat to diagnose as it's not there all the time. My car hasn't been remapped - not really sure I can justify the expense for the mileage I do. Perhaps just as well if the ECU has to be replaced!
 

basstard

Dropping Cogs is Useless
Aug 24, 2002
2,746
0
Roma, Italia
Visit site
I had this on mine and at the time the garage fixed it I didn't understand much about these engines but they told me it was a temperature sensor [they told me "engine temp sensor" which doesn't exist!] of some sort, maybe the fuel temp sensor or the coolant temp sensor as already suggested,,, after changing that sensor I never had that problem again.

Tell me one thing, when the revs stay up, does the car pull more than normal? Mine did, that's why I think it was the fuel temp sensor, cos it affects the quantity of injected fuel.

Anyway, if it's a temp sensor, it will show in the faults if you do a scan with vag com,,,
 

UncleFester

Grumpier by the day!
Apr 30, 2006
4,764
1
Milton Keynes
www.facebook.com
It's not sticking VNT vanes is it - i only ask this as when you cycle them with vagcom, the engine revs will rise to about that level then drop back to 900 or so again.

The other possibility could be worn camshaft lobes?

Just guessing though.
 

basstard

Dropping Cogs is Useless
Aug 24, 2002
2,746
0
Roma, Italia
Visit site
I guess when doing the vanes check, the ecu raises the idle rpm just to get more vacuum to operate the vanes,,, it ain't like vane position has anything to do with idle speed,,,
 

Yella Beeza

Now which way?
Jun 4, 2007
497
0
Edinburgh
Don't think it will be anything worn on my car (only 800+ miles) - unless Pedro raided the secondhand parts bin when the car was built :lol:

Runs fine otherwise. It's as if there's something sticking somewhere. Haven't noticed any overfuelling - no black smoke on acceleration anyway.
 

lutadormma

Guest
Hi Guy's,
New to the Forum and Leon Cupra TDI owner ship. 4 weeks ago I moved over from a Mk 3 Golf VR6 to a LC_TDI for various reasons that I won't bore you with but effectively wanted similar performance to the VR6 but with better fuel economy ( does this sound familiar :)).

Anyway I have purchased a 04 plate Leon Cupra TDI with 57K which on the whole I'm happy with.

I bought it from a main stealer so have full Waranty etc. for a year. I have a few niggles that they have already had it in for but have failed to fix, and have seriously failed to impress me as to their lack of competence ( to be fair I did most of my own work on the VR6 for similar reasons in the past).

The main problem that I have that they so far can't fix is this:

Intermittantly ( but a lot of the time, certainly at least once every journey usually many times per trip) when stopping ( i.e at traffic lights ) when I release the accellerator pedal, the revs fall, but only down to 1200 rpm ( not down to a more normal 850 - 900 rpm) a couple of times it has been as high as 1500 rpm and once at 2k rpm but 99% of the time it is 1200 rpm when its n problem mode. The revs will stay there continually ( I hve left it for more than 15mins still doing it) until I either pull away or quickly dab the accellerator pedal ( if i dab it quickly 7 times out of 10 it will drop to the normal 850-900 rpm and be happy). Its as if something is sticking in that position ( throttle position sensor, valve etc?). It also does it on start up quite a lot ( especially when warm) I know there s an automatic choke type function and its normal for it to start up to 1200 rpm but its supposed to drop back down to normal after a few seconds ( not stay there for minutes).

Some of you may think this is a good fault to have as it will avoid the EGR clogging but it is most annoying. The stealers are researching the problem and are going to consult their MASTER TECHNICIAN :)doh:) and even SEAT direct but I don't hold up much hope due to their recent abilities, so i thought I would throw it open to the forum, to see if you guys can suggest anything.

I have done a search and haven't seen anything specifically like this although I think I am going to try the dielectric grease trick in case its a MAF problem ( seems worth doing even if it doesn't help).


If you can elp I would be most grateful.

Kind regards.

MOZ

Is this happening with the air con, switched on or off?

The reason i ask is that mine was doing the same, but when i turned the air con off, it stopped.
 

Yella Beeza

Now which way?
Jun 4, 2007
497
0
Edinburgh
In my case, the air con (or climate control) is off. No other ancilliaries are on.

Might idle slightly faster with air con on to help keep the battery charged.
 

d_cook88

zιℓ∂נιαη - ρℓαу ωιтн ƒιяє
Aug 28, 2007
128
0
Preston
Mine is also idleing a bit high at times, would a vag come sort this problem possibly? At at least help? where can you get one from and how much for? Cheers

Dave.
 

d_cook88

zιℓ∂נιαη - ρℓαу ωιтн ƒιяє
Aug 28, 2007
128
0
Preston
Thanks, i cant belive this, i had my clutch changed about 2months ago, but about 2 weeks ago it was playing up, it wouldnt come back up on its own. I also had my engine management light on so i took it to the stealers and they charged me £82 to tell me what the problem was. They didnt actually diognose the fault as it took an hour to find the problem with clutch - which they told me was the slave cylinder and would cost £450 to fix, the part it's self only cost £40!?! anyway i took it to a local garage, they dropped the gearbox as required, found that there was nothing wrong with the slave cylinder, it was just a small rubber pipe next to where you bleed the clutch which would of only took 20minutes to fix! While he was doing the job he did me a diognostics and its my tempreture sender unit thats shorting out which is why the car idles high...

So overall the stealers charged me £82 and diognosed a leak which didnt exsist and sold me a part i didnt need, great waste of money!

And for all those who's idleing high take a look at the tempreture sender unit becuase when broke it thinks the engine is running cold so sends more air or fuel in to engine which is why it will idle higher when hot...

Dave.
 

Yella Beeza

Now which way?
Jun 4, 2007
497
0
Edinburgh
Problem with mine is it seems to idle too high at all temperatures.

Starting from cold it does it, except blipping the accelerator seems to cure it, and it returns to normal. Sometimes it's too high when hot, others it's fine. Wonder if it's a faulty connection somewhere, bad earth, etc.
 
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