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Old 21st September 2011, 12:02   #1
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Default Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

Hi Folks

My car just completed 20,000 kms and it was time to change the spark plugs. I went to a MAS garage and got everything changed: Air filter, oil filter, oil and Spark Plugs too.

But when I started moving in the car, it was like I was moving a dead brick. I couldnt go back to the workshop and drove for a tortuous 70 kms on the same day.

The next day I went to the workshop again and told the mechanic about the problem. He said: "We did nothing."

Then I remembered the spark plug and how he has just tapped it to change the gap. He did it arbitrarily.

He looked for the old spark plug and took out the new spark plugs he had installed. There was a difference and he once again adjusted it (based on experience according to him).

When I drove the car, it was much better but still nowhere compared to the performance I was getting before the service. The fact that even after the service my car was performing poorly was like a thorn. I drove the car for two days wondering if the problem was real or because of my perfectionist attitude.

When I searched for threads there was nothing on new Wagon R CNG spark plugs. I decided to check the manual I got along with the car.

There it was. The recommended gap was to be near 0.9-1.0 mm and the spark pug recommended was NGK. Now the guy had installed Denso Spark plug. When I checked on how to measure the spark plug gap in google my search came up with filler gages.

When I searched hardware stores in the area and autombile spare part shops for a filler gage that had 0.8, 0.9 and 1.0 mm measurements I couldnt find. But a helpful hardware shop owner said he could procure one, provided I would definitely buy it. I said yes. It will cost me 50 Rs a pittance and I wondered why the MAS workshop doesnt keep it.

Then a week later (I was driving my car very unhappily) I get a follow up call from my MAS asking me if I was satisfied with the service. I told him about the problem and said that I would return with a filler gauge as I did not trust the way the gaps were being set at the wrokshop.

What followed was surprising. The guy at the phone said that they did have filler gauges!

"Then why was it not used?"

"We are sorry. But please come again and we will set it alright."

I returned to the workshop and the guy. Seeing me second time the guy had a look on his face that told me that I was one of those crazy and fussy customers - a jerk. His manner was very casual. I told him that the gap should be set with a filler gauge and it should be 0.9. He said they never set it at 0.9.

When I insisted, he called his senior. The senior said that the gap should be 0.7 for CNG.

Once again I showed them the manual. Both of them smiles (as if I was a lunatic) and the senior said: "That is for petrol engines. But do as he tells,' to his junior.

By now I was having serious doubts whether I was doing the right thing. But I realized Maruti cant be wrong.

The guy made a face and opened the spark pugs and set the gap to 0.9, this time with a filler gauge.

The way they behaved it looked that I was doing some serious damage to my car.

To my surprise the car is now performing amazingly. It's like breathing again! Not someone with a throttled throat, gasping for the right spark.

Still the performance is at 98% and may be it has got to do with Denso Plugs. Next time I will use NGK for sure.

So moral of the story?

Be there when they adjust spark plugs. The gaps can drastically effect the engine performance. And these people will wash off their hands and you will be driving a dead car for no fault of yours.

My problem was rectified after I drove 900 kms after the service. Thought I would share this with you all.

I realized going back to the garage with
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Old 21st September 2011, 13:25   #2
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

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Originally Posted by syravi View Post
Then I remembered the spark plug and how he has just tapped it to change the gap. He did it arbitrarily.
This was a nice piece of observation you had done that day. Else there are chances that the service centre fleeces you off, doubting all sorts of other possible failures. And glad that your car is back to normal now.
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Old 21st September 2011, 15:27   #3
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

Mech is right. For LPG and CNG one should deduct 0.2mm with the normal value. NGK is best if the vehicle runs on lpg and cng. Plugs hardly cost 65Rs per piece better buy NGK and replace with your local mechanic
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Old 22nd September 2011, 00:18   #4
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

I think he is having Maruti Factory CNG kit .So the .9 mentioned there must be as per Maruti standard for CNG cars.
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Old 22nd September 2011, 00:52   #5
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

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Originally Posted by vijaycool View Post
Mech is right. For LPG and CNG one should deduct 0.2mm with the normal value. NGK is best if the vehicle runs on lpg and cng. Plugs hardly cost 65Rs per piece better buy NGK and replace with your local mechanic

What is the basis for reducing it? Shouldn't you rather increase it to get a fatter and stronger spark, given that CNG is more difficult to combust (slower to burn, etc)?
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Old 22nd September 2011, 09:30   #6
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

Wow, thanks for sharing, I'll get a Feeler Gauge soon, I changed the plugs on my Pulsar 200 and my Zen recently.
The bike however, is not responding as it used to earlier, I might as well check it.
In my Zen, there wasn't much of a difference but still, I'll try.
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Old 22nd September 2011, 09:55   #7
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

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Originally Posted by SAS View Post
What is the basis for reducing it? Shouldn't you rather increase it to get a fatter and stronger spark, given that CNG is more difficult to combust (slower to burn, etc)?
Smaller spark plug gap has an effect of advancing the ignition timing, CNG being a slower burning fuel will need it.
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Old 22nd September 2011, 10:06   #8
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

Larger gap will take fraction more time to jump between electrode and also makes the ignition coil more heated up and can cause failure. Being high octane fuel it burns slower. If the Timing advancer kit is not installed then please do so you will get good power and mileage
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Old 22nd September 2011, 10:15   #9
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

First of all, MASS is not supposed to install anything other than MGP Plugs. Denso is not MGP or for that matter a recommended spark plug for WagonR.

There is almost a double difference when it comes to the pricing of MGP Plugs of 2 makes. While Champion will cost just 65/- Per Piece, NGK on the other hand will cost 125/- Per piece.

I have a WagonR 2006 model which has done 147,000 Kms on the ODO today and I have been mostly replacing the plugs myself over the past 3 years. Though my car's manual mentions two choices - NGK and Champion, somehow I am always inclined for NGKs and it has happened many a times that MASS wont have stock for NGK and will try installing Champion and I decline them.

I then head to a MGP authorized dealer and buy NGK plugs from them and install them myself on the car.
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Old 22nd September 2011, 12:27   #10
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

^^ NGK conventional plugs don't cost that much as far as I know ; Rs.70 each or thereabouts .

I last purchased Champion MGP plugs for my Versa for 60 a piece from the MGP stockist
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Old 22nd September 2011, 13:30   #11
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

^ I dont know if there is a difference then. But for the number of times I have been purchasing the plugs from MGP stockists, they do cost 125/- per piece (MRP as on the box).
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Old 23rd September 2011, 00:12   #12
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

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Originally Posted by Sankar View Post
Smaller spark plug gap has an effect of advancing the ignition timing, CNG being a slower burning fuel will need it.
Since I already have a timing advancer (TAP), wouldn't it benefit from a larger gap and thus a fatter spark, assuming that my electricals can take the additional load?

I've always had the belief of maintaining the spark plug gap on CNG or marginally increasing it, hence the question.
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Old 23rd September 2011, 07:42   #13
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

Quote:
Originally Posted by SAS View Post
Since I already have a timing advancer (TAP), wouldn't it benefit from a larger gap and thus a fatter spark, assuming that my electricals can take the additional load?

I've always had the belief of maintaining the spark plug gap on CNG or marginally increasing it, hence the question.
Set it at manufacturer recommended gap, .9mm would be okay. Don't increase it beyond 1.0mm as it could stress out the ignition coils in the long run.
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Old 23rd September 2011, 08:45   #14
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

I need some help. I just checked my 2000 Zen's manual for the Spark Plug Gap. Surprisingly there is no mention of it.
The engine is 1L MPFi, G10BB, 9.4:1 compression ratio.
Help me please.
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Old 23rd September 2011, 19:27   #15
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Default re: Spark Plug Gap for New K10 Wagon R CNG: 0.9-1.0 mm

Wouldn't shortening the gap for CNG use affect the petrol mode efficiency ?

Maruti CNG is a sequential kit so, I doubt if such an adjustment is required in the first place
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