1.2tsi Cold misfiring and misfiring under boost

[jamieibizaFR]

Having an ongoing issue with my Ibiza 6J 1.2tsi (105) CBZB .
On cold starts the car will misfire but when at operating temp it still does the same thing it misfires and also has a higher than normal idle (normal being around 750rpm ) it will sit at around 900-950rpm.

When accelerating under full boost the car will violently jerk as if you have pressed the brake with your left foot instead of right while accelerating also under moderate boost/acceleration the car will still misfire just not as violent and is more of a judder.

it does not do this everytime I accelerate (full or moderate boost)
The car will just randomly do it , but at idle it will always misfire like the notorious cold misfires .

I’ve recently installed new plugs , new leads and new coil this issue was happening before those parts were changed also the car has recently been carbon cleaned at roughly 40000 miles

if anyone has any advise it’s more than welcome .
Thanks ,
Jamie

 

[KorayKalkan]

Have you read with a diag? even a cheap £15 scanner. Personally I would change the injectors as as next step.

 

[RUM4MO]

The carbon cleaning, was this by the "walnut shells" method directly applied to the inlet side of the cylinder head, and if so, just how choked up was that area prior to being cleaned up/out?

 

[jamieibizaFR]

Have you read with a diag? even a cheap £15 scanner. Personally I would change the injectors as as next step.

Yeah mate I read codes with a snap on code reader but nothing for misfires or anything that is to do with the current issue

 

[jamieibizaFR]

The carbon cleaning, was this by the "walnut shells" method directly applied to the inlet side of the cylinder head, and if so, just how choked up was that area prior to being cleaned up/out?

The carbon clean method that was used was with the gas into the intake but I don’t think it did a good job to be honest

 

[RUM4MO]

The carbon clean method that was used was with the gas into the intake but I don’t think it did a good job to be honest

Correct, that treatment is only useful for cars with port injection, the extra coking that can start to choke up the inlet valve areas on DI engines, does need cleaned out using mechanical methods which include removing the inlet manifold and blasting these areas with crushed walnut shells.

 

[BizaLarry]

I actually have the same problem with the same Ibiza with the same 1.2TSI CBZB engine.

The cylinder 4 HT lead was hanging on by a thread so I replaced all 4 leads and plugs but the issues remains.

I’m going to have a look at the MAF and MAP sensors at some point this weekend, clean those if needed and monitor any changes.

 

[crozz]

For me the issue was spark plugs i just replaced them and all was good. It was only happening with heavy acceleration.

 

[jamieibizaFR]

I actually have the same problem with the same Ibiza with the same 1.2TSI CBZB engine.

The cylinder 4 HT lead was hanging on by a thread so I replaced all 4 leads and plugs but the issues remains.

I’m going to have a look at the MAF and MAP sensors at some point this weekend, clean those if needed and monitor any changes.

My symptoms have massively improved since I have just done a timing chain (not the cause though) the power delivery is much smoother and moving off on the clutch isn’t as jerky but the jerk on heavy acceleration was still there I’ve just changed my turbo actuator with a new genuine unit and it’s seemed to do the trick but I did feel a slight judder yesterday but only once, usually it does a violent jerk and momentarily cuts power when I’d need it most for an overtake , the next thing I’m going to look at is the intake manifold if the jerk persists as a cracked manifold is giving me a lot of the symptoms (try Googling it for a tsi manifold ) it mentions that it sometimes runs perfect without the jolt being there but sometimes the idle will be lumpy and under acceleration have a jolt but not always present . They are cheap enough on ebay to replace with only being plastic so at least it doesn’t cost an arm and a leg , hope this update helped

 

[jamieibizaFR]

I actually have the same problem with the same Ibiza with the same 1.2TSI CBZB engine.

The cylinder 4 HT lead was hanging on by a thread so I replaced all 4 leads and plugs but the issues remains.

I’m going to have a look at the MAF and MAP sensors at some point this weekend, clean those if needed and monitor any changes

I actually have the same problem with the same Ibiza with the same 1.2TSI CBZB engine.

The cylinder 4 HT lead was hanging on by a thread so I replaced all 4 leads and plugs but the issues remains.

I’m going to have a look at the MAF and MAP sensors at some point this weekend, clean those if needed and monitor any changes.

unfortunately the actuator didn’t do the job I still have the jerk/jolt under acceleration , other symptoms you might want to check are the intake manifold as these are symptoms of a cracked manifold I have not checked mine yet but something I will look into and update further. Do you have any improvement to yours ? Have you found any faults ?