Polo issue

[ArendB]

Good day,

I am driving a 2003 Polo 1.4

While driving a constant speed the vehicle sometimes starts jerking. If you then pull over the engine is unable to idle. Only once you give the engine a hard rev does everything go back to normal. The EPC light usually comes on when it starts jerking.

Another issue, not sure if it is related to the issue above. When the car is idling and it is in neutral with the clucht released the engine revs up to about 1200 revs by itself if the vehicle rolls forward on a downhill. The idling goes back to normal once the speed goed beyond 40km\h or if you press the clutch down.

I've removed the throttle body an cleaned it, but the issues still persist.

Where can I look next to resolve the issues mentioned above?

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[Crasher]

So with the EPC light on you did a code read and then after cleaning the throttle body you reset its basic settings in group 060 to match it to the ECU?

[ArendB]

Yes, I did. Can it be the speed sensor that is faulty? The one on the cam shaft.

The reason I am suspecting that one now is because of the enige revving by itself if the car is in neutral, it rolls forward and the clutch is released.

Can it be?

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[ArendB]

I replaced the Manifold Pressure Sensor yesterday, but that did not solve the issue...

What else can it be?

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[Crasher]

The senor on the cam is the G40 and is a position sensor, the speed sensor is called G28 and points at the flywheel and is accessed by removing the inlet manifold. Are there any codes stored?

[ArendB]

Good day,

The only error codes are intake manifold pressure. I am unable to find any leaks. I ended up replacing the manifold pressure sensor but, that did not resolve the issue.


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[ArendB]

It is not the cloil packs and there is nothing wrong with the compression.

I am starting to suspect the electronic accelerator pedal. The reason for this is, when you do a cold start, the engine instantly revs up to about 2000rpm and then immediately returns to the normal idling speed. Then the engine idles normally.

Furthermore, when driving at 120km/h and you take you foot off the gas and apply it just a little bit to maintain a constant speed, the car starts julting. If you stop then, it will not idle and the EPC light illuminates. Then the only way you can get the engine to function normally is to redline the engine for about two seconds. After doing that, the engine idles normally again.

What are your thoughts on this?

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[Crasher]

You can watch the two accelerator pedal position sensors in measuring blocks.

[ArendB]

How do I do that?

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[Crasher]

With a diagnostic system capable of displaying measuring blocks such as VCDS