Hi,
Since I bought my 2017 Golf 7 (1.4 TSI 125HP, CZCA engine) two years ago, I feel rough idle.
Few times after buying it, I had a CEL so I brought it back to the dealer who told me that it was sporadic misfire on one cylinder.
They cleared the error, unmounted/remounted the spark plug and told me everything is fine, if there is no CEL, no problem...
So I drove with this issue for two years now but I was still worried about that and started to investigate myself on this.
What I found first, is that I have misfires counters which increment when I feel little shake of the engine.
I counted 15 misfires in about 2 minutes during my test at cold start.
Here are the actual values of misfires counters:
- Misfires cylinder 1: 1252
- Misfires cylinder 3: 1118
- Misfires cylinder 4: 1650
- Misfires cylinder 2: 941
I checked 2 spark plugs, because they had been changed by the dealer just before I bought the car (I was thinking they did not put the right reference...).
The reference is Ok and they seems well I think (pictures joined).
I launched a log at cold start to push further the investigation (file joined).
I am not an expert so it is hard for me to diagnose.
What I see is that :
- the STFT start decreasing when I feel engine shake (here it decrease until -7%)
- the LTFT decrease until -4,7% (when reaching this value and STFT near 0%, the engine is more smooth)
So it seems the mixture is too rich, but I do not know why and I do not know if it is the real cause of misfires.
Note that, I filled my last 2 tanks with SP98, before I used SP95E10.
I was thinking about an oxygen sensor issue, but it does not seems to be.
I saw on forums that it can be carbon build up in the intake that could be the issue but the car has only 70.000km...
Thank you for your help !!
Note that idle is rough at cold start but not only.
Also, no modification on the engine, only OEM pieces, always revised by the dealer.
Since I bought my 2017 Golf 7 (1.4 TSI 125HP, CZCA engine) two years ago, I feel rough idle.
Few times after buying it, I had a CEL so I brought it back to the dealer who told me that it was sporadic misfire on one cylinder.
They cleared the error, unmounted/remounted the spark plug and told me everything is fine, if there is no CEL, no problem...
So I drove with this issue for two years now but I was still worried about that and started to investigate myself on this.
What I found first, is that I have misfires counters which increment when I feel little shake of the engine.
I counted 15 misfires in about 2 minutes during my test at cold start.
Here are the actual values of misfires counters:
- Misfires cylinder 1: 1252
- Misfires cylinder 3: 1118
- Misfires cylinder 4: 1650
- Misfires cylinder 2: 941
I checked 2 spark plugs, because they had been changed by the dealer just before I bought the car (I was thinking they did not put the right reference...).
The reference is Ok and they seems well I think (pictures joined).
I launched a log at cold start to push further the investigation (file joined).
I am not an expert so it is hard for me to diagnose.
What I see is that :
- the STFT start decreasing when I feel engine shake (here it decrease until -7%)
- the LTFT decrease until -4,7% (when reaching this value and STFT near 0%, the engine is more smooth)
So it seems the mixture is too rich, but I do not know why and I do not know if it is the real cause of misfires.
Note that, I filled my last 2 tanks with SP98, before I used SP95E10.
I was thinking about an oxygen sensor issue, but it does not seems to be.
I saw on forums that it can be carbon build up in the intake that could be the issue but the car has only 70.000km...
Thank you for your help !!
Note that idle is rough at cold start but not only.
Also, no modification on the engine, only OEM pieces, always revised by the dealer.
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