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Old 13th November 2016, 12:31   #361
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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Originally Posted by halfbytecode View Post
I think it may be due to the battery going bad. I have experienced strange and unusal behaviour in my 2010 Vento 1.6 TDI lately. The current battery has been used for over 50,000 kilometers, and it has been 2 years since it was installed.
Exactly, initially I had felt the same.
Now a days, cold start demanding a long cranks.

But how does it relate to the higher rpm?
I'm thinking of something related with vacuum leak. I do not have OBD connector to read the DTCs ( no MIL shown on Cluster though ).

Also, engine start to misfire a couple of times during cold start. Have you observed the same in your car?
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Old 13th November 2016, 12:38   #362
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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Originally Posted by keeru View Post
Exactly, initially I had felt the same.
Now a days, cold start demanding a long cranks.

Also, engine start to misfire a couple of times during cold start. Have you observed the same in your car?
This is a common problem of 1.6 TDI. After using Rapid & Vento, I can surely say this with confidence.

Engine misfiring is due to cold temperature as well as improper supply of air to the intake manifold. The Oxygen Sensor might take some time to get warm before the revs become smooth. After some 60 seconds warm up, this disappears. Improper Injection also results in misfiring.

I make sure the car is driven in 1st & 2nd gear for a brief moment when this happens. Try the same.
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Old 13th November 2016, 13:31   #363
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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This is a common problem of 1.6 TDI. After using Rapid & Vento, I can surely say this with confidence.
The below video posted by fellow bhpian.
From last three weeks have stated to notice exactly the same during cold start and during that time, rpm shoots up to 1000-1100.

As I can't dare to keep the engine vibrating like that for a long, I immediately turn the IGN to OFF and again after Cranking, the engine behaves normal as if nothing has happened and the rpm also settles to 700-800rpm.



Note: No warning\MIL on the cluster.

Have taken an appointment at VW service station for Tuesday. Meantime, I want to know if poor battery cause this problem? (Car was parked for three weeks and was not used for that time after which I started to see this symptom)
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Old 13th November 2016, 13:33   #364
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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Originally Posted by keeru View Post
Exactly, initially I had felt the same.
Now a days, cold start demanding a long cranks.

But how does it relate to the higher rpm?
I'm thinking of something related with vacuum leak. I do not have OBD connector to read the DTCs ( no MIL shown on Cluster though ).

Also, engine start to misfire a couple of times during cold start. Have you observed the same in your car?
Some VAG group engines are known to increase RPM to compensate for the higher load on the battery, to provide current from the alternator. This also happens if the battery is aged, thereby putting more load on the alternator.

I experience the RPM going up and down by 50-ish, and the engine noise increasing and decreasing in succession, at cold starts.

Quote:
Originally Posted by CarguyNish View Post
This is a common problem of 1.6 TDI. After using Rapid & Vento, I can surely say this with confidence.

Engine misfiring is due to cold temperature as well as improper supply of air to the intake manifold. The Oxygen Sensor might take some time to get warm before the revs become smooth. After some 60 seconds warm up, this disappears. Improper Injection also results in misfiring.

I make sure the car is driven in 1st & 2nd gear for a brief moment when this happens. Try the same.
The outside temperature (32 C) does not seem to be an issue, at least for me. I have not experienced this behaviour over the last 5 years and like 1 lakh kms, even in sub 4 C temperatures, when the MID puts on the low temperature warning.

However, this issue was present in 2010-2011, that was fixed by a software update to the ECU.

Last edited by halfbytecode : 13th November 2016 at 13:34.
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Old 13th November 2016, 18:39   #365
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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Originally Posted by keeru View Post

Hi Guys, my 2014 GT TDI clocked 52k kms started to increase the rpm when the engine is idling and when AC is ON.
Hey keeru, I have a 2014 GT TDI myself and have noticed this behaviour where the RPM shoots up by couple of 100s when the AC is turned ON. In fact, I have also observed that when the car is allowed to rolled down an incline slowly with the engine running, the RPM increases slightly as well, without any throttle input. This I believe is a regular behaviour.

But please do post the outcome of your appointment with VW A.S.S and the diagnosis as it would help me & other 1.6 TDI owners as well.


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Those black alloys look sweet. I love the design of those alloys too. Lensos?
Hey Shibu, these are GTR rims which were custom painted to go with the shade on my GT. I have sort of got over this look now and have some things planned to enhance this as well

Will keep the updates posted 'As & When' they happen.
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Old 13th November 2016, 19:28   #366
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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Originally Posted by Vik0728 View Post
In fact, I have also observed that when the car is allowed to rolled down an incline slowly with the engine running, the RPM increases slightly as well, without any throttle input.
That is infact like you said normal behaviour where-in on a slope, you let the wheels drive the transmission and in turn the engine, and when that happens, the ECU cuts off fuel supply and you can also see the max FE reading in case you are looking at the instantaneous FE on the MID. This is how all cars behave, and I guess is not related to the high rpm after AC.
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Old 14th November 2016, 13:55   #367
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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Originally Posted by Vik0728 View Post
Hey keeru, I have a 2014 GT TDI myself and have noticed this behaviour where the RPM shoots up by couple of 100s when the AC is turned ON.
Today morning I have observed the rpm is increasing to 1000 even without AC is turned ON.

I'm not able to understand if this is a common behavior which I didn't observe in the past.

Can any one of you keep an eye on the rpm level when car is idling (may be when you stop at traffic signals)?
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Old 14th November 2016, 22:43   #368
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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But please do post the outcome of your appointment with VW A.S.S and the diagnosis as it would help me & other 1.6 TDI owners as well.
Though my appointment is fixed for Tuesday at Elite Motors, managed to get the car checked on today at Apple Auto.

There was an error logged "1598 drive battery voltage intermittent"
Attached Thumbnails
Volkswagen Polo 1.6L GT TDI : Official Review-1598.jpg  

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Old 14th November 2016, 23:01   #369
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

Explanations gave by A.S.S are as below.

1. Senior Technician:
He is on leave today but listened to the problem over phone and replied to me "while the battery is being charged the rpm gets increase, might need a battery replacement"

2. Technician:
"Increase in rpm during idle is common and can show it on any other car parked for the service" but later, he couldn't reproduce (tested on another GT TDI) whose rpm is constant at 750rpm even when AC is ON

3. Service Manager (not Service Advisor):
"Park the car and tomorrow we will start analysing the issue" for which I was bit skeptical to leave the car for their R&D work because of below reason

I've got to know (unofficially) from a Technician working at Apple Auto A.S.S that my car is second after a Vento 1.6TDI which has a similar problem and even after replacing the battery did not solve the problem. Pointers towards faulty ECU??

Now I need inputs from experts on the below:

1. Do I really need to worry\care if the rpm increases by 100-200 during idle ?
2. If there is any vacuum leak, will the rpm drops down back to normal ?
3. If the battery is being charged during idling, will the rpm increase?

Sometimes during cold start, have noticed the cranking takes long (may be 1.5 to 2 sec) and my car is 2.5 years old (need to check the battery MFD).

Pls advice!
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Old 15th November 2016, 15:39   #370
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

Quote:
Originally Posted by keeru View Post

1. Do I really need to worry\care if the rpm increases by 100-200 during idle ?
2. If there is any vacuum leak, will the rpm drops down back to normal ?
3. If the battery is being charged during idling, will the rpm increase?

Sometimes during cold start, have noticed the cranking takes long (may be 1.5 to 2 sec) and my car is 2.5 years old (need to check the battery MFD).

Pls advice!
Dear Keeru,

I doubt if the particular way engine is idling has anything to do with vaccum leaks. And a vaccum leak would normally register as a separate error code or affect the operation of actuators that depend on it (one of those mutiple solenoids that control turbo vane angles or EGR valves or even the brakes themselves).

The error code '01598' as per your screenshot is one that is indicative of a dying battery or one that is not charged completely (see here). I suggest you take a detailed battery health report (not just the basic specific gravity readings) and assess whether you need a new battery or not first.

The battery is being charged continuously when the engine is running. However whether a low state of charge or output voltage results in ECU slightly increasing the idling RPM, I am not sure.

Regarding the misfires you face during cold starts, it could be due to glow plugs not operating at their intended temperature, perhaps due to the dying battery not able to provide sufficient juice. So overall, I would suggest you check the battery first, (you can get those detailed battery health reports at a good dealer/service center of reputed battery brands) and proceed from thereon.


Cheers,
Avinash
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Old 16th November 2016, 01:22   #371
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Default Re: Volkswagen Polo 1.6L GT TDI : Official Review

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However whether a low state of charge or output voltage results in ECU slightly increasing the idling RPM, I am not sure.
Hi Avinash, this morning I've managed to take few basic readings of the battery with the multimeter.

Before proceeding with the readings, below is the snapshot of the information found from owners manual.

From this, the first point which clearly states that the rpm level during idling can be increased when alternator drives more current.
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Volkswagen Polo 1.6L GT TDI : Official Review-img_5420.jpg  

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