[Rajeev.Ayyappan]

Hi guys.

Became the proud owner of a 2020 Thar LX D MT CT on 4th December. I was very happy with the vehicle and it became my default daily driver for 20 days, 60-40 city and highway. HSRP plates and RC arrived at the dealership on 18th.

Since the car had run 800 km, I asked the service Centre to club the number plate fitting with first service. Car was picked up by dealer’s driver on 23rd and dropped off back the same day. Service done was only general check up and cleaning. No mechanical work or oil changes. The same day evening, took the car on the highway for about a 100 kms. Felt a strange vibration on the clutch pedal.

The next day while driving in the city, realized that the engine was revving randomly to 2000 rpm and back even on neutral and in traffic lights when clutch is depressed with gear in slot. Absolutely no accelerator input given. Once clutch is released and gear is engaged the revvs correspond to accelerator. I am sending the car for check up tomorrow.

In my experience so far with the dealer, they are also in the dark about several thing related to the new Thar. They could not even demonstrate the convertible opening and closing mechanism properly, same thing with the 4x4 lever. The SA struggles to shift it during demo and I had to learn from the net regarding these two things. So I am quite apprehensive as to whether they would be able to identify and solve this problem quickly.

BHPians, kindly guide and advise regarding the possible reasons for the self revving and a solution. This is my first post on Team BHP, so forgive me for any mistakes in the post.

Thank you.

[dark.knight]

Originally Posted by Rajeev.Ayyappan

This is my first post on Team BHP, so forgive me for any mistakes in the post. Thank you.

Two things come to mind :

1) Clutch position sensor

2) Idle air control actuator

Get both checked, the norm is that the revs will drop once the clutch is pressed i.e, rev hang, but if the opposite is happening here then it could be the clutch position sensor which is unable to send the right electrical signals of clutch position to the ECU. The idle air control valve modulates RPM according to engine temp in neutral, perhaps that should be looked at as well, cleaned if necessary.

Should be a minor issue, just suggest the above to the service advisors as well, in case they lack technical knowledge (they usually lack).

[ph03n!x]

Originally Posted by Rajeev.Ayyappan

Hi guys. Became the proud owner of a 2020 Thar LX D MT CT on 4th December.
...
The same day evening, took the car on the highway for about a 100 kms. Felt a strange vibration on the clutch pedal. The next day while driving in the city, realized that the engine was revving randomly to 2000 rpm and back even on neutral and in traffic lights when clutch is depressed with gear in slot. Absolutely no accelerator input given. Once clutch is released and gear is engaged the revvs correspond to accelerator. I am sending the car for check up tomorrow. In my experience so far with the dealer, they are also in the dark about several thing related to the new Thar.

First off, congratulations on your new steed! Wish you a lot of mile munching, making-your-own-roads with it!

Like @dark.knight has said this is probably because of incorrect reading from one of the sensors. But going by my experience and those of others, it's not the sensors themselves that are at fault but the connections to them. Have the service center ensure that the connecting sockets are tightly in place, and the individual wires in those sockets do not have a play when they are plugged in.

If you are not sure about your service center's capabilities, see if you can drive up to Coimbatore - CAI Mahindra has a very good technical team (read up on my ownership thread about the issue I faced) and are very competent.

[Raghu M]

Originally Posted by Rajeev.Ayyappan

The next day while driving in the city, realized that the engine was revving randomly to 2000 rpm and back even on neutral and in traffic lights when clutch is depressed with gear in slot. Absolutely no accelerator input given. Once clutch is released and gear is engaged the revvs correspond to accelerator.

Rajeev, first of all, congratulations on owning the current head turner in the Indian automotive market. I experienced this kind of stuff in my old Estilo. The car generally settles around 1000 RPM but that day, it was strangely going over 2000 and then coming back when engaging gears. I immediately called my mechanic, as it was serviced only the previous week. He mentioned that it could highly be the case of fuel adulteration. I was shocked as I used to fill up in a regular pump, he mentioned to me that the fuel station is not to be trusted and try filling in another station. I did that after a couple of days and the problem was gone. Try doing that. If the issue doesn't settle, then I think you need to visit the service station. Hope this helps.

[Rahul Bhalgat]

Hi Rajeev,
Congratulations on purchasing the Thar. Wish you lakhs of happy miles ahead.

As other members have pointed out, it could be problem with the idle air sensor. I have little doubts on the clutch position sensor, which is a simple on-off sensor.

Also check the Mass Airflow Sensor (MAF sensor). I am not sure if your Thar has a MAF sensor but bad MAF sensor does cause fluctuations in the idling rpm.

Since the problem started after the service, it could be something simple like water ingress into the sensor connector or the loose connector.

[Rajeev.Ayyappan]

Originally Posted by ph03n!x

First off, congratulations on your new steed! Wish you a lot of mile munching, making-your-own-roads with it!

Like @dark.knight has said this is probably because of incorrect reading from one of the sensors. But going by my experience and those of others, it's not the sensors themselves that are at fault but the connections to them. Have the service center ensure that the connecting sockets are tightly in place, and the individual wires in those sockets do not have a play when they are plugged in.

If you are not sure about your service center's capabilities, see if you can drive up to Coimbatore - CAI Mahindra has a very good technical team (read up on my ownership thread about the issue I faced) and are very competent.

Bang on ph03n!x. The service guy called me to inform that the accelerator sensor was misaligned and on realignment, the problem was solved. But since this is a brand new vehicle, they are replacing the whole accelerator assembly under warranty. In the meantime, got a call from Mahindra regional office in Chennai regarding the issue and was assured of a solution by them. Waiting for delivery later today. Will update as to the status then. Thanks to Team BHP for such quick and valuable responses.

Originally Posted by Raghu M

Rajeev, first of all, congratulations on owning the current head turner in the Indian automotive market. I experienced this kind of stuff in my old Estilo. The car generally settles around 1000 RPM but that day, it was strangely going over 2000 and then coming back when engaging gears. I immediately called my mechanic, as it was serviced only the previous week. He mentioned that it could highly be the case of fuel adulteration. I was shocked as I used to fill up in a regular pump, he mentioned to me that the fuel station is not to be trusted and try filling in another station. I did that after a couple of days and the problem was gone. Try doing that. If the issue doesn't settle, then I think you need to visit the service station. Hope this helps.

Thank you Raghu for your input. The last time I filled diesel was around 10 days ago and had no problems for about 300 km before sending for service. Highly doubt that fuel could be the issue. Anyway, service guy says that the accelerator sensor is misaligned and they are changing the whole assembly. Cheers.

[distiller]

Hi Rajeev, first of all congratulations for your new Thar & wishing you many happy & wonderful miles ahead.
I also had encountered this kind of problem with the MAF sensor located on the exhaust side albeit the engine was a Petrol one & different make of vehicle. The experience was similar, unexpected rise & fall in rpm. I am not sure if the diesels also have MAF or similar sensors which control or fine tune the fueling. Please keep us posted with the rectification done by ASS.

[Rajeev.Ayyappan]

Update : The accelerator assembly has been changed. Everything is fine now. Took the vehicle on a 200 km drive and no problems. Thank you Team BHP.