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Old 5th May 2011, 13:31   #511
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

^^ in my new gen i10 the shift indicator always asks me to shift up as soon as the RPM meter touches 2K and to down shift when it touches 1K. I am getting FE of 11-12 in city with 100% A.C. Have not been able to take any highway trip yet, will let you guys know.

But point here is, 1.5-2K RPM seems to be range one should be in for achieving a better FE. This is what Hyundai recommends (via its shift indicator). Isnt the same with other companies too ?

p.s: GTO too has recommend in his first post to shifts gears in the RPM range of 1.5 - 2 k

Last edited by dar3dev|l : 5th May 2011 at 13:34.
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Old 5th May 2011, 13:37   #512
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Quote:
Originally Posted by libranof1987 View Post
It is valid for all vehicles. Gear change should happen between 2.5k -3k rpm for optimum engine performance and FE. (of course, you can be on the 5th gear at 30 km/hr or 100 km/hr on the 3rd at the cost of the engine and FE).


Engine knocking is what you hear when the engine is in high gear and it is not getting enough fuel. You don't necessarily hear it all the time as the in current mpfi engines, the fuel flow is adjusted.
Yes - you do not hear sounds but the car feels a bit heavier and refuses to accelerate when put in a higher gear at lower speeds. I hope you are referring to this only as engine knocking.
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Old 5th May 2011, 15:39   #513
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

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Originally Posted by Saanil View Post
Yes - you do not hear sounds but the car feels a bit heavier and refuses to accelerate when put in a higher gear at lower speeds. I hope you are referring to this only as engine knocking.
Yep!

Quote:
Originally Posted by dar3dev|l View Post
^^ in my new gen i10 the shift indicator always asks me to shift up as soon as the RPM meter touches 2K and to down shift when it touches 1K. I am getting FE of 11-12 in city with 100% A.C. Have not been able to take any highway trip yet, will let you guys know.

But point here is, 1.5-2K RPM seems to be range one should be in for achieving a better FE. This is what Hyundai recommends (via its shift indicator). Isnt the same with other companies too ?
I have driven a i10 with the gear-shift indicator too - and I don't find it very practical.

Upshifting at 2k means for that particular gear, your minimum speed is very high. Even if you get your foot off the accelerator, the speed falls below the min. speed and it asks you to downshift.

Upshifting by 2.5k - 3k rpm gives you that buffer when you cannot accelerate or have to drop down your speed marginally. Imagine following the recommendation and changing gears every few seconds just because the gear change is "optimum".

Going by i10, I'd have to be on the 5th at 40 km/hr itself! It is just a suggestion, made by a comp. not aware of surrounding or taking into account unusual situations.

Ultimately, it is your driving instinct that you have to employ!
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Old 7th May 2011, 15:23   #514
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

^^^ +1 to that.

I have a lot of friends who kept saying that the Vista Safire65 suffers from poor FE.

My sister, who was the primary user till sometime back used to always complain of poor FE. She used to get 12-13 kmpl (with low use of A/c) on her city runs. I once went as a passenger with her to understand what she does.

She was shifting at 10-20-30-40-50, which basically translates to 1700-1900 rpm and keeping it there. According to her the car sounded strained above these RPM's .

I did try to explain to her that it was not strained, but she was actually getting poor FE due to this. She did not believe me, as her driving school instructor had told her this. (tell me about ghar ki murgi dal barabar).

I asked her to leave the car with me for a week. We went and filled fuel (Auto cut-off only) 31.4 litres. Reset one of the two trip meters and I started using the car. I would only shift at 2200-2400 rpm (Dont look at the speed!). And drive steadily. Also used AC pretty regularly. Once the fuel indicator started showing low, we both went to the ame fuel bunk at the same time (late night) and again filled (auto cut off) - 28.7 litres. So basically I used up 28.7 litres. The trip meter read 447 kms, which translated to an FE of 15.6 kmpl. Did this a couple of times more and was able to get an overall figure of 15 kmpl with use of AC (30%).

The point is - Try upshifting at a slightly higher RPM, you dont strain the engine that way because you lose momemtum while shifting if it is too low. The engine has to work harder at maintaining your motion, which translates to lower FE.
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Old 9th May 2011, 12:33   #515
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Default 1998 Maruti Esteem - Low Fuel Efficiency

Creating a new post as I couldn't find a similar post for a carb'd Esteem.

I recently (Nov 10) purchased an Esteem from a colleague. The car consistently delivers a FE under sedate driving conditions.
Petrol: ~6
LPG: ~5


Few points I'd like to highlight:
I am a sedate driver, I change gears and don't rev hard - very rarely revving post 2k rpm.
I live in Mumbai and hence am forced to drive in crawling traffic at times, though not choc-o-block.
The AC is almost always on.
I have checked the FE multiple times with the tank full to tank full method.
A plug chop shows that the engine is not running too rich.

Has anyone faced a similar problem? Anything I should check? I have got it checked at MASS and a trusted local garage; both are of the opinion that I will not get a better FE within the city.
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Old 9th May 2011, 13:14   #516
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Default Re: 1998 Maruti Esteem - Low Fuel Efficiency

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Originally Posted by TheSandman View Post
Has anyone faced a similar problem? Anything I should check? I have got it checked at MASS and a trusted local garage; both are of the opinion that I will not get a better FE within the city.
There's two things you can do

1. Get rid of the catalytic convertor or replace it with a new one (it must've got clogged in all these years the car has been running)

2. Do a complete overhaul of the carburettor - get it done from a knowledgeable guy - split the complete carb and reassemble it with new gaskets and O rings (buy the aftermarket "major" gasket kit - that's the only way to get all those o-rings in one shot!). Do change the pilot and main jets while you are at it (make sure you use esteem jets and not M800 or Zen jets)

On a similar note, in traffic I personally have never got more than 9-10 KMPL with the carb esteem in city traffic.
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Old 9th May 2011, 17:06   #517
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Default Re: 1998 Maruti Esteem - Low Fuel Efficiency

First thing first, how much has the car run? Start with a complete service and a comprehensive tune up.
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Old 9th May 2011, 19:37   #518
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Quote:
Originally Posted by techn0l0gist View Post
Get rid of the catalytic convertor or replace it with a new one (it must've got clogged in all these years the car has been running)
Thanks techn0l0gist!
Any idea how much a new cat cone would set me back by?
I'll get the carb tuneup done ASAP

Quote:
Originally Posted by Jaggu View Post
First thing first, how much has the car run? Start with a complete service and a comprehensive tune up.
68k kms. I have already gor a complete service, including a tune-up done from MASS (Chamunda), didn't help at all.

Last edited by manson : 9th May 2011 at 19:40.
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Old 9th May 2011, 20:32   #519
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

What all was checked? Complete tune up will include:
  • Carb clean up, overhaul and tune up
  • Setting valves to spec
  • Complete ignition check up, including spark plugs, wires and coil
  • Timing and carb micture adjustment
  • Air and fuel filter inspection, cleaning/replacement

If all this was done and still no difference, then you might want to do an engine compression test done to see if everything is fine. Next thing to check would be the clutch. And maybe even brakes for jamming.
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Old 9th May 2011, 21:19   #520
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Sandman: Sai Service are one the best MASS available in Mumbai. Used to get my 97' Zen serviced and tuned with them. And as mentioned earlier by Jaggu and techno, yes a carb clean up and tune up is a must do! You can also try changing gears at higher RPM like 2200 - 3000 since the engine would be getting the load of AC and LPG.

Btw, 10 kmpl is something that is the best this car can give just on petrol !
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Old 10th May 2011, 07:32   #521
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Quote:
Originally Posted by dar3dev|l View Post
Sandman: You can also try changing gears at higher RPM like 2200 - 3000 since the engine would be getting the load of AC and LPG.

Btw, 10 kmpl is something that is the best this car can give just on petrol !
So shifting at a higher RPM can deliver a better FE? I thought it was just the opposite, Or maybe I just haven't understood you?

Guessing that you mean 10kmpl without AC, can i concur that I get 8kmpl with AC in traffic and 6 with AC in traffic?

Quote:
Originally Posted by Jaggu View Post
What all was checked? Next thing to check would be the clutch. And maybe even brakes for jamming.
This is what was done:
  • Carb clean up, overhaul and tune up
  • Timing and carb micture adjustment
Guess I gotta get the rest done as well. Will check and update, including brakes and clutch..
Btw, I the car shudders when releasing the clutch.. been happening ever since I got the car in Nov'10; and ever since I'v been dreading a weak clutch, Please tell me I'm wrong... Or is it just a retarded timing?
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Old 10th May 2011, 10:14   #522
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

^^ well when you have your AC and running on LPG the load on the engine is a little too much. So the engine will surely running out of breath at lower RPM (1-2K) so shifting gears between them might consume more fuel. Thus the reason of changing at higher RPM. This was the case with my 97 Zen too. I got the engine tuned and started changing gears at higher RPM's and found the car giving a little better FE !

with 10 KMPL i meant with AC on petrol. Atleast, thats what i was able to get out of my carb zen !

Last edited by dar3dev|l : 10th May 2011 at 10:16.
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Old 10th May 2011, 11:01   #523
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Quote:
Originally Posted by Jaggu View Post
What all was checked? Complete tune up will include:
  • Carb clean up, overhaul and tune up
  • Setting valves to spec
  • Complete ignition check up, including spark plugs, wires and coil
  • Timing and carb micture adjustment
  • Air and fuel filter inspection, cleaning/replacement
If all this was done and still no difference, then you might want to do an engine compression test done to see if everything is fine. Next thing to check would be the clutch. And maybe even brakes for jamming.
Hi Jaggu, can you think of any place in Bangalore who'd check a logan petrol for idling vibration and poor FE (8kmpl without AC in city). I unknowingly mentioned to them that the car was once used on CNG (till about a year ago in Delhi) and immediately they decided they can't deal with it because it was once used on CNG and all they'd do is a regular service. Should I just go to another A.S.S and not mention the CNG history? These guys said for CNG installation, a hole must have been drilled in the intake manifold - though that's definitely not the case!
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Old 10th May 2011, 13:03   #524
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Better to stick with another service center and keep the CNG mention out
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Old 10th May 2011, 22:00   #525
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Default Re: ARTICLE: How to get the maximum Fuel Efficiency

Quote:
Originally Posted by TheSandman View Post
Please tell me I'm wrong... Or is it just a retarded timing?
1) Clutch overhaul for an esteem is not very expensive.
2) Why do you doubt timing? if you have done the tune up? I suggest you try one of the recommended shops by TBHPians in Mumbai once.
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