[RBhargav]

I have a Skoda Rapid 1.6 TDI Ambition 2012 (bought it in 2019 at 65000 km)

Except for the first gear, the engine jerks when I try to accelerate even moderately. This happens usually at 1200 to 2000 RPM. The total power output also seems to have gone down a bit, just by feeling. The low-end torque has slightly reduced, and at the high-end, I don't feel like the boost is hitting max. If I drive the car for more than half an hour at 60+ kmph, it seems to get better.

The car has a K&N replacement air filter in good condition. Engine oil and filter were replaced 2 months back. No error codes in diagnostics. The service centre says the timing belt is OK. They don't really seem to be interested in troubleshooting this.

1. 6 months back I had an injector failure and replaced it with an overhauled one. Don't know if any of the injectors have started to underperform. Does this seem like a fuel system issue? Should I try a fuel additive? (I once used a fuel additive in my bike and it was a disaster, so I am hesitant).

2. Can the issue be in the ECU? Should I do a re-map? I saw code6 tuners are near my area, are they reliable?

3. If it is an exhaust system issue (near the cat), how can I double-check myself?

[dhanushs]

Originally Posted by RBhargav

Except for the first gear, the engine jerks when I try to accelerate even moderately. This happens usually at 1200 to 2000 RPM. The total power output also seems to have gone down a bit, just by feeling.

I myself have a similar model Vento, and the symptoms you say point out to an injector failure. Assuming the car is properly serviced at the A.S.S. Otherwise, a blocked diesel filter can also be an issue.

[JayPrashanth]

Originally Posted by RBhargav

I have a Skoda Rapid 1.6 TDI Ambition 2012 (bought it in 2019 at 65000 km)

Except for the first gear, the engine jerks when I try to accelerate even moderately. This happens usually at 1200 to 2000 RPM. The total power output also seems to have gone down a bit, just by feeling. The low-end torque has slightly reduced, and at the high-end, I don't feel like the boost is hitting max. If I drive the car for more than half an hour at 60+ kmph, it seems to get better.

The car has a K&N replacement air filter in good condition. Engine oil and filter were replaced 2 months back. No error codes in diagnostics. The service centre says the timing belt is OK. They don't really seem to be interested in troubleshooting this.

1. 6 months back I had an injector failure and replaced it with an overhauled one. Don't know if any of the injectors have started to underperform. Does this seem like a fuel system issue? Should I try a fuel additive? (I once used a fuel additive in my bike and it was a disaster, so I am hesitant).

2. Can the issue be in the ECU? Should I do a re-map? I saw code6 tuners are near my area, are they reliable?

3. If it is an exhaust system issue (near the cat), how can I double-check myself?

Is your car on the stock clutch? If yes, a replacement may be in order. Shuddering while the car is moving at idle speeds is a typical warning sign of a clutch that needs replacing.

Also, do NOT attempt modifications until the car's performance is back to stock-car levels.

Cheers,

Jay

[mac187]

Originally Posted by RBhargav

Except for the first gear, the engine jerks when I try to accelerate even moderately.

I had the same issue with my Swift long ago. It culprit was the clutch. Had to change the complete assembly. I would suggest you to get it diagnosed with the A.S.S first, do not mention clutch issue as they will happily replace it and hand you a hefty bill. Let them figure out the issue first.

[RBhargav]

Originally Posted by JayPrashanth

Is your car on the stock clutch? If yes, a replacement may be in order. Shuddering while the car is moving at idle speeds is a typical warning sign of a clutch that needs replacing.

Originally Posted by mac187

I had the same issue with my Swift long ago. It culprit was the clutch. Had to change the complete assembly. I would suggest you get it diagnosed with the A.S.S first, do not mention the clutch issue as they will happily replace it and hand you a hefty bill. Let them figure out the issue first.

I forgot to mention that the clutch was replaced 4 months back. It had become hard and was slipping a bit. The clutch seems fine now. This problem has started since the onset of cold weather, that is why I suspect the fuel system.

Originally Posted by dhanushs

I myself have a similar model Vento, and the symptoms you say point out to an injector failure. Assuming the car is properly serviced at the A.S.S. Otherwise, a blocked diesel filter can also be an issue.

Thanks for pointing that out, diesel filter might be an issue too. I do go to the ASS but only once or twice a year and moreover I might be filling up dirty diesel since I usually drive to rural areas and remote locations.

I am scared to talk about injectors with the ASS because they are ready to replace anything I speak of. Wanted to flush the fuel system with an additive once before I jump into injector repair/replacement.

[ObsessedByFIAT]

I too feel it is a problem with the injector failure. A friend is going through a similar issue on his Figo TDCi.
The car shudders a lot and has gone in limp mode.

Since you have already replaced an injector with an over hauled one, I would assume that it is the weak link here.

Do you see any tell tale lights on the console?

[RBhargav]

Originally Posted by ObsessedByFIAT

Do you see any tell tale lights on the console?

No lights. The ECU is unaware of the injector performance. None of the injectors has failed yet, but they might be underperforming, not enough to turn on lights on the console.

I read from a thread that Skoda / VW injectors on the TDI engines from 2014 or older models are going kaput one by one. Seems like I'm a sitting duck.

Today I changed the diesel fuel filter. Also took out my K&N air filter to clean and re-install it. Once done I will take it for a ride and see if these made any difference.

If not, my last chance would be to flush the injectors with an additive and hope for the best.

[4wdrunner]

Everything you said makes me suspect carbon build up in the engine. I would try to decarbonize the engine.

[RBhargav]

[Update]

Cleaned the air filter, changed the diesel fuel filter and filled an almost empty tank with good quality diesel. The low end torque seems slightly better. But the mid-range pickup after gear change remains as before.

Next test will be fuel additive to clean the fuel system and engine. I am also suspecting the turbo side - EGR, boost regulator or some sensor/actuator might not be working perfectly and thus not giving enough boost?

[ruhtam]

If you're okay taking your car to a Bosch diesel service station, they would do a free check on the injectors. They mostly have one equipment that checks the sensor values. Another equipment they may have is a flow checker that can easily identify any problems with an injection pressure, but you may have to pay them a little.

I own a Vento TDI and have personal experience with a similar issue. I cleaned 2 of my injectors post that check and the low speed shudder went away. Get a good mechanic to put your injectors in test rig and get them serviced.

But, do all this if you're comfortable giving them outside.

[Malluspec]

Do try the liquimoly injector cleaner additive , it has worked wonders on many vw tdi injectors i know of . Mix it with the diesel and do an Italian tuning .

[RBhargav]

Originally Posted by ruhtam

If you're okay taking your car to a Bosch diesel service station, they would do a free check on the injectors. They mostly have one equipment that checks the sensor values. Another equipment they may have is a flow checker that can easily identify any problems with an injection pressure, but you may have to pay them a little.

I own a Vento TDI and have personal experience with a similar issue. I cleaned 2 of my injectors post that check and the low speed shudder went away. Get a good mechanic to put your injectors in test rig and get them serviced.

But, do all this if you're comfortable giving them outside.

Thanks for the advice! Yes I will need to do that. Most Skoda VW owners have told me their injectors are the failure points. Better safe than sorry on a long ride.

Originally Posted by Malluspec

Do try the liquimoly injector cleaner additive , it has worked wonders on many vw tdi injectors i know of . Mix it with the diesel and do an Italian tuning .

I am currently burning this LiquiMoly additive, have to see the difference yet. Fingers crossed!