Erratic Revs at idle.

[allclownsareevi]

Alright boffins, has anyone had similar problem at this?

At idle my 130 1.9TDi Superb idles at just below 1000rpm steadily.

When using the fans/heater (especially on full) the revs will drop off every 5 seconds or so. They drop suddenly, as if the car is about to stall, but then obviously the ecu catches it and throw more fuel through ... the revs regain to previous levels .... then 5-6 second later the cycle starts again.

It's more pronounced when it's cold too ... like early mornings this week.

I'll be honest, I haven't checked anything yet. I fitted a dragon box a while back and it was a slightly hurried affair so I was thinking perhaps it's the battery terminals not being seated correctly. Checking those is on my to do list whilst doing a full service sometime soon, only I haven't gotten around to it yet. Got all the parts just need to find the time. A friend of mine kindly offered to do the cam belt for me (a VW mastertech) .... hmmm I may see about getting pics of that. If it's easy enough I may post a guide up. If it's not the terminals I'll have the battery checked for holding a charge.

Just wondered if anyone had any pointers or similar experience of this?

Cheers in advance.

[Supurbia]

Check the hoses to the airbox and the egr valve, the valve one can split and suck air in, normally throws the EML on though.

[Bluefox]

Hmm, if it's only when the fans/heating's on I think it might have something to do with the aircon compressor.

Does it make a difference if you use the heating on "econ"? If it does I'd say it's definitely the aircon.

[allclownsareevi]

Cheers for the replies, I tried to recreate the problem this morning , but all was fine no matter what I did ... typical. Next time it happens will have a fool with AC settings. Have noticed it happens when fans are on, not sure if it's AC related, usualy have it on econ anyhow but who knows.

Otherwise next time I get my head under the bonnet I'll check air hoses and battery terminals.

Just wondered if anyone else had had this problem, maybe there was a common fix. Hmmmmmm.

[Bluefox]

Hmmmmmm indeed.

If it's not the aircon, I'm not sure... but I'll go with the EGR suggested by Superbia

[allclownsareevi]

Ok, so re the erratic revs when my Superb idles I've figured out the following.

Since fist posting have figured out it happens when the car is re-started AND the climatronic fans are engaged. ie: When started first time it's ok. However let's say you go on a short journey (thus getting the engine warmed up a little) then you re-start the car, it's then the problem becomes evident.

Whether the climatronic is set to AC or Econ makes no difference.

Now my inferior brain tells me it could be something like the air flow temp sensor, seeming as it's somehow tied into the fact the engine isn't started from cold. However, being as it's also obviously related to electrical drain on the system I'm not so sure.

So, once again, hmmmmmmmmm.

[Bluefox]

Ok, so re the erratic revs when my Superb idles I've figured out the following.

Since fist posting have figured out it happens when the car is re-started AND the climatronic fans are engaged. ie: When started first time it's ok. However let's say you go on a short journey (thus getting the engine warmed up a little) then you re-start the car, it's then the problem becomes evident.

Whether the climatronic is set to AC or Econ makes no difference.

Now my inferior brain tells me it could be something like the air flow temp sensor, seeming as it's somehow tied into the fact the engine isn't started from cold. However, being as it's also obviously related to electrical drain on the system I'm not so sure.

So, once again, hmmmmmmmmm.

Have you had your alternator checked?

[Bluefox]

However let's say you go on a short journey (thus getting the engine warmed up a little) then you re-start the car, it's then the problem becomes evident.

Hmm... I've just re-read that.

Can dervs suffer from fuel starvation??

[allclownsareevi]

Have you had your alternator checked?

Yeah that occurred to me too, but no haven't had it checked yet. Right now it's a niggle rather than a problem but it does need sorting. I've gotten a load of parts and fluids to service the car this week sometime, so will get under the bonnet and take a look around.

Had a friend fire up VAG COM and the EGR values were within specified ranges.

First thing I'll try is reseating the battery terminals and greasing them up with vaseline. I used to use axel grease to keep them free from corrosion, until someone pointed out axel grease is non-conductive.

A new air, pollen, oil and fuel filter are going in, along with new oil, so we'll see if it makes a difference. If not the first thing I'll do is remove the Dragon box and see if the problem remains. Kinda want to isolate that as the cause before sensors start getting replaced.

[allclownsareevi]

Well a solution was finally found to this and credit where credits due, Supurbia you were right, it was the egr valve causing it.

I had hooked up VAGCOM and read the EGR values which were all within tolerance so I assumed that wasn't the cause, however after disconnecting the EGR at a later date the engine ran fine.

Anyhow just figured I'd say thanks and post it up in case it helps anyone else.

Cheers.

[Supurbia]

Well a solution was finally found to this and credit where credits due, Supurbia you were right, it was the egr valve causing it.

I had hooked up VAGCOM and read the EGR values which were all within tolerance so I assumed that wasn't the cause, however after disconnecting the EGR at a later date the engine ran fine.

Anyhow just figured I'd say thanks and post it up in case it helps anyone else.

Cheers.

Glad you got it sorted, and thx for saying thx in the PM you sent me.

[allclownsareevi]

Glad you got it sorted, and thx for saying thx in the PM you sent me.

Hey no worries buuuuuddy. Thanks for saying thanks about me saying thanks.

[Chris Dut]

Well a solution was finally found to this and credit where credits due, Supurbia you were right, it was the egr valve causing it.

I had hooked up VAGCOM and read the EGR values which were all within tolerance so I assumed that wasn't the cause, however after disconnecting the EGR at a later date the engine ran fine.

Anyhow just figured I'd say thanks and post it up in case it helps anyone else.

Cheers.

who hooked up vag.com and disconnected the EGR valve?

runs like a little sewing machine now