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Old 25th November 2016, 00:45   #1
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Post Tata Zest Revotron misfiring. Is E10 fuel the culprit?

Hi All,

I'm owning a Tata Zest Revotron from Nov 2014.

Ownership thread - http://www.team-bhp.com/forum/test-d...ms-update.html (Zed, my Red Tata Zest. EDIT: 20 months & 25,000 kms update)

The car has been mostly doing good for the first one year and is currently clocking 33K kms. I'm from Kolkata and I fill up the car almost always from a nearby IOC fuel station as long as I'm within city limits. Roughly about 7 months back I noticed that the pumps at this IOC station had a green sticker on it saying "Petrol 10% Ethanol". I questioned the people at the pump and was replied in affirmative that it indeed is the E10 specification of petrol that was being dispensed. I checked my owners manual and did not find any specific mention of E10 specification or compatibility of the same. The car was all running good till now.

A thread on E10: http://www.team-bhp.com/forum/techni...-blending.html (Ethanol 5%, 10% blending) found similar information on wiki too.

The 3rd service (Basically 2nd service, the first being just a checkup) of my car was due at 2 years completion or at 30K kms. But I had a trip planned in Oct 16, thus requested to get it service a little earlier at around 27K Kms. The trip was a 4.5k Kms trip to Himachal from Kolkata. About a couple of weeks before the day I did my first service I got this Check Engine issue.

The temperature icon and the check engine icon gave a tale tale beep and flashed in unison, the car starts knocking with sudden loss of power. I slowly got the car to a halt and turned off the ignition. Took out the key and started the car in about 20 secs, and the code was gone. The AC was not cooling for about 3 to 4 mins approx and there after all was normal.

I immediately reported the issue at the service center. They checked the vehicle and found that there were 2 DTE code for misfire. One for multiple cylinder and the other for cylinder no 3. However, the technician explained that this was a temporary code and hence not much to be done at that point, he cleared the code and we were done.

All was well for almost 2 weeks and I went for the 3rd service. The technician replaced spark plugs, engine oil and filter, fuel filter etc as per schedule. I noticed the actual person working on the vehicle had a tough time opening one of the HT cables to replace the spark plug, it was a bit stuck. He struggled for a good 10 mins or so before opening it. All was done and I was getting ready to get on with the trip with my newly serviced car the very next day. (I know its a great mistake to get your car serviced close to a big trip, bud had to succumb to it).

I could not start as planned since the same knocking issue as described above started happening more frequently as I was about to hit the highway. I had to return back. All codes were temporary I would know since it was gone with the next ignition cycle. But eventually it stopped being so and became permanent, the car was literally grasping to breathe. I returned back home.

Next day re-visited the service center and it was found that one of the HT cables was torn, not snapped but the insulation got severed. All four cable were replaced right away and I was off to my trip for 4.5K Kms that was 6th OCT '16. The car ran without any further issues during the trip. I filled up before starting from the same IOC and presumably with the same E10 petrol. We returned on the 16th OCT 16. I started using the same IOC pump again, isolating this issue being caused by a faulty HT cable.

I got the same issue in the 1st week of Nov 16. Service center did a tappet adjustment. I was told that the specs for the same has changed since Nov '14 and hence it's a step to try for this issue.

Immediately I found that the engine note got harsher and I was getting some uneven clutters during idling. I was told that the noise will subside as the car keeps running.
So upon my next visit on 19 Nov'16 the A/C idler, idler timing belt, Timing belt tensioner were replaced. Most of the noises were gone but still a faint clutter remained.

I got the same issue again about 3 days back and gave the car at service center on 24th Oct '16, this time it was again temporary single instance, have been using the same IOC fuel station.

Presently my car is in the service center getting checked for a root cause of this issue. TML has engaged one of their top of the line technical person and today the fuel line was cleaned after emptying and washing the fuel tank. The faint noise that remained was from the alternator bearing, as reported to me, they will be replacing the same. TML is hinting at a possibility of the E10 Fuel causing the issue and will probably request me to use non E10 petrol from any of the other oil companies and check, which I'll do. But I find it hard to believe that E10 would cause this issue as per several articles on the net. No drop in mileage or power as such, in-fact the car has been giving pretty good mileage recently.

So, trying to understand if E10 fuel can actually cause such an issue? As far as I know E10 is yet to be approved country wide and it's not yet approved in West Bengal. Probably Maharashtra is the only state using it. I'll get back to the IOC fuel station guys and find out if in the mean time E10 has been stopped and its only the sticker that remains.


I'll really be obliged if any one has any advice, steps, a similar problem or any information to share. Also, I being not so technically abridged would request a few opinions, if any thing obvious is being missed here.

Many thanks!
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Old 25th November 2016, 01:06   #2
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Default re: Tata Zest Revotron misfiring. Is E10 fuel the culprit?

I own a Zest XMS RT from 2015/03, which has covered ~25000 km in the past year and half. I have filled from an IOC bunk on two occasions so far, one being the very first day I bought the car and the other being about a month ago.
I do remember seeing the board at the IOC bunks stating that what is sold here is a blend of ethanol and petrol, but I do not remember the percentages. I had not heard about E10 petrol before.

I did face the misfire and vehicle stop once and now that you mention it, it was indeed when I had filled the petrol from an IOC bunk. Just as you also faced, all I had to do was pull over, stop for 10 seconds, restart the car and off she went as though nothing had happened at all.
I did notice some amount of knocking while driving in city traffic, when I had the IOC fuel, so I went back to my usual BPCL station after that incident
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Old 25th November 2016, 04:25   #3
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Default re: Tata Zest Revotron misfiring. Is E10 fuel the culprit?

I am not sure if you are allowed to use E10 in an engine which has not been designed for it. The manufacturer specifically states if the car is E10 compatible. It will be good to change the petrol pump to a non E10 and see if the problem persists.
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Old 25th November 2016, 15:45   #4
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Default Re: Tata Zest Revotron misfiring. Is E10 fuel the culprit?

Since your car had a HT cable disintegration, that could cause the ignition coil to develop a short circuit/snag. Has any check been made on the ignition coil (with a replacement coil - since so much has already been done on it).
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Old 26th November 2016, 17:56   #5
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Default Re: Tata Zest Revotron misfiring. Is E10 fuel the culprit?

I think the only way to check the ignition coil is a current ramp test using a scope and current clamp. But I am not sure whether ass is equipped. Is it a coil on plug or wasted spark ignition?. You can swap the ignition coil and wait till the problem occurs. If the misfire occurred on another cylinder, then you can narrow it to coil.

Last edited by GTO : 28th November 2016 at 10:35. Reason: Typos
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Old 29th November 2016, 08:57   #6
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Default Re: Tata Zest Revotron misfiring. Is E10 fuel the culprit?

Quote:
Originally Posted by perty View Post
I did face the misfire and vehicle stop once and now that you mention it, it was indeed when I had filled the petrol from an IOC bunk. Just as you also faced, all I had to do was pull over, stop for 10 seconds, restart the car and off she went as though nothing had happened at all.
I did notice some amount of knocking while driving in city traffic, when I had the IOC fuel, so I went back to my usual BPCL station after that incident
Thanks perty, that points to the fuel, I'll change the same immediately.

Quote:
Originally Posted by extreme_torque View Post
I am not sure if you are allowed to use E10 in an engine which has not been designed for it. The manufacturer specifically states if the car is E10 compatible. It will be good to change the petrol pump to a non E10 and see if the problem persists.
Hi extreme_torque,
Indeed, I actually questioned TML about the same, they never really came back to me with a verdict. On internet I received mixed reactions. If you follow that link in my post, it points to no short comics for using E10. However, TML did report now and have requested to use only normal petrol. Thanks a lot!

Quote:
Originally Posted by 1100D View Post
Since your car had a HT cable disintegration, that could cause the ignition coil to develop a short circuit/snag. Has any check been made on the ignition coil (with a replacement coil - since so much has already been done on it).
Hi 1100D,
Thanks a ton for your sugggestion, they have checked the entire ignition circuit and found carbon deposit on the spark plugs. All four spark plugs were replaced. Ignition coil is ok as of now.

Quote:
Originally Posted by dracul View Post
I think the only way to check the ignition coil is a current ramp test using a scope and current clamp. But I am not sure whether ass is equiped. Is it a coil on plug or wasted spark ignition?. You can swap the ignition coil and wait till the problem occurs. If the misfire is occured on another cylinder, then you can narrow it to coil.
Hi dracul,
Thanks for checking it out, as of now the ignition coil seems to ok as per TML. As of now fuel is the suspected culprit.


The car was kept in the service center for a full 2 days. The fuel line and the tank was cleaned and washed. Ignition circuit checked, abnormal carbon deposit on spark plugs were found, all four were changed. I reported a slight noise while idling. Alternator bearing was changed but the noise prevailed, the noise was finally found due to alternator belt. Now the car is super silent and smooth.

Thanks to all of you for your guidance, got the car back and it feels good so far.

Thanks,
Arindam
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