Rough Idle/ Regen 2.0tdi

[Ec123]

Hi, i own a 2.0Tdi 184hp leon 2015 with 77k miles.

My car has started to have a rough idle when it is in Park it idles at 1k and there is a vibration/shake. The dpf is not blocked as i have done a forced regen and i go on motorway drives atleast 4 times a week.

Does anyone know that the issue can be?

I have taken it to a mechanic and he did say there was an injector imbalance, there is a loop where injector 1 goes high then drops then injector 2 goes high and drops and the loop carries on.

 

[BillyCool]

I have a 2014 184 and had similar issue. It was an injector imbalance. Mine are getting replace shortly.

 

[Ec123]

What issues have you faced with the injector imbalance?

 

[BillyCool]

What issues have you faced with the injector imbalance?

The only thing I noticed was when at idle, usually when the car is warm, I get the vibration/shake. It has been getting more frequent. I had a carbon clean in December and as part of the clean all of the live data gets checked. I was told that there was an injector imbalance. I have a Carista OBD dongle and put an app on my phone (Car Scanner Pro) to measure the injector deviations in real time. You can see the values changing at idle.

So far, the only issue has literally been the shake at idle but I think it's impacting fuel economy. It can also cause power loss and acceleration issues. My DPF has just been replaced so I'm going to see how it runs since that can impact fuel economy etc so it's hard to know if the DPF and/or injectors were contributing to that. The plan is to replace the injectors in the next few weeks once I've made sure the DPF situation is all good. If the car shake gets really bad I've been told that it can wear the engine mounts.

Either way, I will be sorting them out.

 

[SuperV8]

1k rpm is high - unless it is doing a regen.
Normal hot idle is more like 800ish.
How are you sure it's not trying to regen?

 

[Ec123]

Because of how often it happens and the dpf has had a forced regen before and i often take it on the motorway

 

[Ec123]

The only thing I noticed was when at idle, usually when the car is warm, I get the vibration/shake. It has been getting more frequent. I had a carbon clean in December and as part of the clean all of the live data gets checked. I was told that there was an injector imbalance. I have a Carista OBD dongle and put an app on my phone (Car Scanner Pro) to measure the injector deviations in real time. You can see the values changing at idle.

So far, the only issue has literally been the shake at idle but I think it's impacting fuel economy. It can also cause power loss and acceleration issues. My DPF has just been replaced so I'm going to see how it runs since that can impact fuel economy etc so it's hard to know if the DPF and/or injectors were contributing to that. The plan is to replace the injectors in the next few weeks once I've made sure the DPF situation is all good. If the car shake gets really bad I've been told that it can wear the engine mounts.

Either way, I will be sorting them out.

Mine is the exact same, it only happens when the car is at optimum temperature, i am taking it to the garage this weekend, thanks for your reply.

 

[SuperV8]

Because of how often it happens and the dpf has had a forced regen before and i often take it on the motorway

I can understand how Injectors could be causing your rough idle - but not sure how they would also cause elevated idle speed of 1000rpm? I know when it's trying to regen it raises rev's to 1000.

You can get a cheap bluetooth ODB dongle and app and it will tell you if it's 'trying' to do an regen and how often.
Could be a faulty pressure sensor - so the car keeps 'trying' to regen? Just because it has had a forced regen and some motorway trips doesn't mean there isn't something wrong with the DPF system - high oil consumption or faulty injectors could also damage your DPF.

 

[Ec123]

I can understand how Injectors could be causing your rough idle - but not sure how they would also cause elevated idle speed of 1000rpm? I know when it's trying to regen it raises rev's to 1000.

You can get a cheap bluetooth ODB dongle and app and it will tell you if it's 'trying' to do an regen and how often.
Could be a faulty pressure sensor - so the car keeps 'trying' to regen? Just because it has had a forced regen and some motorway trips doesn't mean there isn't something wrong with the DPF system - high oil consumption or faulty injectors could also damage your DPF.

I have changed the pressure sensor as a mechanic told me if it carries on then do this, it wasn’t too expensive so i replaced it however no change. I’ll have a look at getting an obd scanner have you got any recommendations?

 

[BillyCool]

I have changed the pressure sensor as a mechanic told me if it carries on then do this, it wasn’t too expensive so i replaced it however no change. I’ll have a look at getting an obd scanner have you got any recommendations?

A lot of us use an OBD dongle and various apps for your phone rather than buying a dedicated scanner. I use a Carista dongle and Carisata app for fault codes and car customisation, VAGDPF to monitor the DPF and recently added Car Scanner Pro to monitor injector deviation. Other people will have their preferred options.

 

[SteveGSXR600K1]

I have a 2014 184 and had similar issue. It was an injector imbalance. Mine are getting replace shortly.

View attachment 53864

When are you supposed to run this live data, when the engine is cold/warm, idling, whilst driving, etc? How do you know what to look for in the graph, as yours seems to have lots going on. Injector 1 starting off a lot higher than the other three, then injector 4 looking like its going to the moon! Should all 4 have a uniform pattern?

 

[BillyCool]

When are you supposed to run this live data, when the engine is cold/warm, idling, whilst driving, etc? How do you know what to look for in the graph, as yours seems to have lots going on. Injector 1 starting off a lot higher than the other three, then injector 4 looking like its going to the moon! Should all 4 have a uniform pattern?

You can run it any time. I was mainly checking mine when idling, as that is when I had the issue. Usually when the car was warm.

The injectors constantly adjust the flow rate to maintain a smooth idle. The injectors are meant to deviate by no more than +0.5/-0.5 mg/str. Ideally, the values are all much the same. Anything above +2.0 mg/str suggests an issue. If one injector does that, the others have to compensate,

In this picture all 4 injectors are behaving themselves, all within +0.5 or -0.5. The lines are steady and flat. Then, at idle, injector 1 shoots up and all 3 injectors compensate by going negative but mainly injector 3.

In this one - injector 1 goes up to +3.0 mg/str (bad news) and injector 3 picks up most of the slack.

On this one, injector 1 and 4 are having issues, causing 2 and 3 to compensate.

The lines should all be flat and steady at much the same values and not deviate too much. Mine are not. Anything between +2.0 and 3.0 (or more) are signed of bad injectors, excessive fuel or compression issues. Mine are not right for whatever reason so I'll monitor and see how they go. I do think they'll get replaced at some point.

 

[SteveGSXR600K1]

Thanks for the explaination. Makes sense now!
very rare, but I occasionally notice a feint wobble at idle. Definetly notice one when it's doing a regen at standstill, but never worry about it.
I'll have to get my OBDeleven out and see what my injectors are like.

 

[Ec123]

You can run it any time. I was mainly checking mine when idling, as that is when I had the issue. Usually when the car was warm.

The injectors constantly adjust the flow rate to maintain a smooth idle. The injectors are meant to deviate by no more than +0.5/-0.5 mg/str. Ideally, the values are all much the same. Anything above +2.0 mg/str suggests an issue. If one injector does that, the others have to compensate,

In this picture all 4 injectors are behaving themselves, all within +0.5 or -0.5. The lines are steady and flat. Then, at idle, injector 1 shoots up and all 3 injectors compensate by going negative but mainly injector 3.
View attachment 53916

In this one - injector 1 goes up to +3.0 mg/str (bad news) and injector 3 picks up most of the slack.


View attachment 53918

On this one, injector 1 and 4 are having issues, causing 2 and 3 to compensate.



View attachment 53919

The lines should all be flat and steady at much the same values and not deviate too much. Mine are not. Anything between +2.0 and 3.0 (or more) are signed of bad injectors, excessive fuel or compression issues. Mine are not right for whatever reason so I'll monitor and see how they go. I do think they'll get replaced at some point.

How would you know which injector is the issue, are you going to get them tested?

 

[SteveGSXR600K1]

I've just ordered an OBDeleven 3 to replace my OBDeleven Gen1, so I'll wait until this arrives before trying this test. This change was mainly because it works with Android Auto and I can monitor things like regens, etc. The live data has options 'Injection amount deviation cylinder 1', etc, so assuming that's the correct options.

 

[BillyCool]

How would you know which injector is the issue, are you going to get them tested?

The injectors should not really deviate more that +0.5 mg/str. Anything over +2.0 is considered a sign of faulty/worn injectors. From the images above you can see that injectors 1 and 4 seem to have the issues. I don't need to test them as I can see the data.