Polo 1.2 tsi misfire / rough pickup
Discussion
I had my Polo 1.2 tsi 2015 model (CZJC engine, 65000 miles) serviced (major) at a VW main dealer last year, and the cam belt and tensioner changed. Since then the car is hesitating slightly when the throttle is gently opened.
If you are driving down a gentle incline on overrun at around 1800rpm and gently press the accelerator pedal, the engine ‘stumbles’ or hesitates before picking up. Also if you drive along a flat road at say 35mph in 4th gear, and just feather the throttle to keep a constant speed, the engine runs rough and jerks through the transmission as it alternately hesitates and picks up. It was fine before the dealer had it.
It’s been back to the dealer several times, once when the hesitation became so marked that the engine warning light came on and generated a fault code.
When read (OBD2) the fault said ‘coil pack cylinder 2&3’. These were swapped round with 1&4 and the problem was better for a few days but eventually returned.
Since then I’ve replaced all the coil packs and checked all the spark plugs but the fault remains.
The problem feels more like a fuel problem, a bit like a car with a carburettor and choke hesitating when it’s not warmed up properly, and the choke has been pushed in too early.
I’ve read that certain direct injection VW engines suffer from carbon build up in the inlet manifolds but apparently not the 1.2tsi.
My next thought is to look at the fuel injectors, but this is either a complex job to do yourself, or an expensive job to have done.
Would anyone have any ideas, comments to make, please?
If you are driving down a gentle incline on overrun at around 1800rpm and gently press the accelerator pedal, the engine ‘stumbles’ or hesitates before picking up. Also if you drive along a flat road at say 35mph in 4th gear, and just feather the throttle to keep a constant speed, the engine runs rough and jerks through the transmission as it alternately hesitates and picks up. It was fine before the dealer had it.
It’s been back to the dealer several times, once when the hesitation became so marked that the engine warning light came on and generated a fault code.
When read (OBD2) the fault said ‘coil pack cylinder 2&3’. These were swapped round with 1&4 and the problem was better for a few days but eventually returned.
Since then I’ve replaced all the coil packs and checked all the spark plugs but the fault remains.
The problem feels more like a fuel problem, a bit like a car with a carburettor and choke hesitating when it’s not warmed up properly, and the choke has been pushed in too early.
I’ve read that certain direct injection VW engines suffer from carbon build up in the inlet manifolds but apparently not the 1.2tsi.
My next thought is to look at the fuel injectors, but this is either a complex job to do yourself, or an expensive job to have done.
Would anyone have any ideas, comments to make, please?
No, completely different. Ive replaced a faulty injector on my other car, also a Polo 2008 model with the BZG engine (1.2l 3 cylinder).
On that one the injectors are simply held into the inlet manifold with th clip and can be changed in about 10 minutes.
The Tsi has direct cylinder injection, with the injectors hidden behind a forest of plumbing, and they screw directly into the cylinder head, need a slide hammer to remove, and special tools to replace the seals when its all re assembled.
On that one the injectors are simply held into the inlet manifold with th clip and can be changed in about 10 minutes.
The Tsi has direct cylinder injection, with the injectors hidden behind a forest of plumbing, and they screw directly into the cylinder head, need a slide hammer to remove, and special tools to replace the seals when its all re assembled.
I know little about engines. However I recently bought my son's 2010 1.2 Polo from him, and he advised me to put E5/supreme fuel in it about every 3rd tank as the car runs better when it has better fuel in it. It certainly does, smoother and better MPG but the price of it stinks, try a tank and see if it helps?
Fuel E5/10 makes no difference.
Didn’t change spark plugs as they were new at last service and in good condition, having only done 8000 miles.
The misfire isn’t do do with ignition, IMO. It’s a hesitation, exactly like a car with a carburettor and a cold engine when it hasn’t been given enough choke.
Something was done at the service which made the car start doing this, as it was fine before.
Didn’t change spark plugs as they were new at last service and in good condition, having only done 8000 miles.
The misfire isn’t do do with ignition, IMO. It’s a hesitation, exactly like a car with a carburettor and a cold engine when it hasn’t been given enough choke.
Something was done at the service which made the car start doing this, as it was fine before.
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