Entries from October 2007 ↓

Preamble
About 4-months ago, we’d had a look at the do’s and don’ts of converting present generation MPFi cars to LPG or CNG. With increasing availability of the two at various places coupled with the costs of petrol forever heading north, most people are seriously considering going in for such conversions. So here’s a QnA that I hope most of you will find informative and useful…

Question
Several Radio Taxi service providers in Delhi/ NCR have been providing ‘B’ segment cars such as Esteem etc that run on CNG. The fleet size of such dual fuel vehicles is more than 300. Over the last 6 months or so, I have traveled in these cars and found the ride experience quite comfortable. Although there is some impact on the initial acceleration, the cost of running which is almost entirely in the city, is down to about Re. 1/- per km. I understand that Maruti Udyog does not provide any company CNG kit fitted vehicles, however, there are several private agencies in Delhi that install such RTO approved CNG kits with endorsement on the Registration Certificate for a total cost of around Rs. 40,000/-.

I own an Esteem-VXi, September 2004 model, Cost Rs. 5 lacs, which came with a 4year/ 80,000 Kms warranty. The car has done almost 30,000 kms in the last 2-1/2. The monthly running is expected to go up to around 2,500 kms per month over the next 2-1/2 to 3 years, thus making the financial viability/ payback of installing a CNG kit even more attractive although the 4-year warranty shall lapse.

Assuming that one can live with the slight impact on the initial acceleration and that’s inevitable with CNG, my main question to you is what will be the impact of using CNG on the total ownership costs e.g. Repair & Maintenance costs, Life and Resale value of such dual fuel Esteem, if any?

Answer
Difficult to say, though engine life expectancy can certainly go up coz CNG is a lot cleaner fuel compared to petrol AND oil/spark-plug change intervals go up by atleast 50% on km basis with CNG running. The resale value will definitely take a beating for understandable reasons. Recently, I too had a ride in a similar one from IGAP/Delhi to Noida, got talking to the driver and gathered that:

i) The Esteem in question was almost 4-yrs old/BS-II/Mpfi and had done 2.5 lac kms during this time - with the engine still going strong. According to him, it was mainly due to the owner’s policy to change engine oil every 5,000 kms/once a month. If I may add to that, running on CNG with the engine properly re-tuned for it is another contributory factor.

ii) According to that cabbie, the power loss in CNG mode was about 25% (15/20), good enough for running around NCR, whereas what’s text-booked is about 10-15%. This made sense coz he was comparing the power loss from the Mpfi Esteem level/85 bhp in petrol, as against a carb type/65 bhp less 10-15% that it becomes in CNG mode.

iii) His Esteem with his gentle driving returned almost 20 km/kg-cng and at times, he had to take two-tankfuls during a day.

iii) What turned out to be an interesting info was that his owners had placed a bulk order for 30-Esteems about 4-yrs back and Maruti Udyog had them all CNG-Kitted at their works prior to delivery.

The point I’m trying to make here is given the capability (FYI, Suzuki is doing a CNG-Baleno in next door Pakistan and that too with a 1.3 lr engine for taxi trade), if MUL can do it for bulk orders and still uphold their warranty, why can’t they offer CNG Esteem’s for taxi/personal use in India also - even as a retro-fit by its dealers as GM and Ford are doing for their Optra and Ikon. In the process, this will also throw out of business, fly by night retro-fitters who get away by supplying cheap but so called RTO Approved but technically incompatible kits for Mpfi’s, leaving the poor ignorant buyers high and dry.

So, it may be worthwhile for you to contact your MUL Dealer to find out if he’s prepared to do it for you w/o affecting your warranty, as I understand some of the Dealers in Mumbai are already doing so, perhaps after getting into an understanding with MUL.

Preamble
Ever since the World saw the first single-cylinder petrol engine driven Car, a ‘Carburetor’ became synonymous with it. Later on with the advent of multi-cylinder Engines, so did the ‘Distributor’ or ‘Delco’s.

During the last Century, both evolved considerably – till the ‘Euro-II’ like Pollution Norms got the better of them. For, the Carbs worked on a principle of ‘reaction’, which could easily get ‘stifled’ for so many reasons.

Thus, a System of ‘controlled-feeding’ of Fuel + Air + Ignition Spark to an automotive engine evolved in the early ‘80s. A ‘system’ like that had to be based on its ‘needs of the moment’, such as the load on it, engine rpm/road speed etc. Let’s see basically how such a system works…

It all started with ‘Single-point’ Fuel Injection Systems – virtually an electronic replica of the Carbs of yore but soon led to ‘multi-point’ Fuel Injection Systems – some what akin to the’ Multi-Carb’ high performance Cars of the past.
‘Mpfi’ stands for ‘multi point fuel injection’. This system injects fuel into individual cylinders, based on commands from the ‘on board engine management computer’ – popularly known as the Engine Control Unit/ECU.

The ‘Fuel Injectors’ are precision built fast-acting ‘Solenoid Valves’, like Washing Machine Water inlet Valves. These have either single or multiple ‘Orifices’ which ‘spray’ fuel into the inlet manifold of a Cylinder upon actuation, from a common Rail/Header pressurised to around 3 bar, fed by a high pressure electrically drive fuel pump inside the Petrol tank of the Car.

The ‘on-board’ ECU primarily controls the Ignition Timing, idling speed and quantity of fuel to be injected. The latter is achieved by means of controlling the ‘duration’ for which the Injector solenoid valve coil is kept energized – popularly known as the ‘pulse-width’.

The ECU in turn is controlled by the ‘data input’ from a set of ‘SENSORS’ located all over the Engine and its Auxiliaries. These detect the various ‘operating states’ of the Engine and the performance desired out of it. Such Sensors constantly monitor: 1. Ambient Temperature, 2. Engine Coolant Temp., 3. Exhaust/manifold temp., 4. Exhaust ‘O2’ content, 5. Inlet manifold vacuum, 6. Throttle position, 7. Engine rpm, 8. Vehicle road speed, 9. Crankshaft position, 10. Camshaft position, etc.

Based on a ‘programmed’ interpretation of all this input data, the ECU gives the various ‘commands’ to the Engine’s fuel intake, idling speed and spark ignition timing systems, to deliver an overall satisfactory performance of the Engine from start to shut down, including ‘emission control’.

To get the best out of an MPFi System, one should use – a) The OE recommended Petrol Additive or the new generation ‘Premium’ Petrol’s REGULARLY and b) NEVER Tamper with the OE Wiring Harness of the Car – EVEN to install the ubiquitous Music System OR any other Electrical Accessory - other than those ‘approved’ OE/Dealer and designed to suit the Car’s Wiring Harness ‘Couplers’. ‘BUTCHERING’ OF THE ORIGINAL CENTRAL WIRING HARNESS OF A VEHICLE IS AN ABSOLUTE TABOO FOR MPFi CARS.

Despite such a foolproof system and programming of the ECU, situations do arise in cold climates that lead to either starting problems first thing in the morning or the engine stalling under some or the other driving conditions.

Following are the possibilities that can lead to such situations - assuming that the Car has been serviced in line with the OEM recommendations:

i) That one is not allowing enough time for the fuel-pump to ‘prime’ the System, as evidenced by an audible ‘click’ sound in the Cabin of the FP going off after a few secs of turning on the ignition.

ii) That one is giving too short a Crank. The first one in the mornings has to be relatively a little longer than the ones during rest of the day.

iii) That one is unknowingly stepping on the Accelerator Pedal - even partially - which one is not supposed to for Mpfi’s.

iv) Faulty Coolant Temp and Air Intake Sensors/their Couplers - usually the latter for Cars less than 2-yrs old.

v) Worn-out or larger than recommended Spark-plug Gaps.

vi) Clogged Fuel-Injectors – one should be using a good Petrol Additive regularly like a daily Vitamin Pill with our regular/unleaded Petrol – or instead, the now more freely available detergent pre-mixed fuels.

vii) The main reasons for a petrol engine to stall are - a) either under or over supply of fuel, b) loss of ignition c) mechanical locking while shifting gears or braking etc., or d) un-sustainable/low idling rpm. If these happen rather regularly, other than ‘c’, then the engine needs to be ‘scanned’ at an authorised service centre to determine the cause and remedied accordingly.

Preamble
With the winter setting-in across most parts of the Country and Pre/EU-II kind of M800s and other Carbureted/Mechanical Distributor Type Cars like the Zen’s and Esteem’s still being there in appreciable numbers, I feel it’s time to draw Car Owners’ attention to the topic under discussion.

Most non-MPFi Car Owners experience that when they start the car in the morning or after it has been shut down for 5-6 hours, it feels very sluggish. Engaging the car in 1st gear and upon even stepping on the gas pedal, the car does not ‘speed up’.

This goes on for a while and only after the Temp. Gauge needle crosses the ‘C’ and goes beyond, the car feels ‘normal’. All this despite the Engine Tune being in good order.

The answer to this is that a ‘cold’ Engine is inherently sluggish, to prevent it from spewing out excessive pollutants during its warm-up period. To overcome this difficulty, a device called ‘Radiator Thermo-Valve’ is incorporated in the Cooling System, along with a ‘by-Pass’ circuit, with the sole purpose of enabling the Engine to reach it’s designed operating temp. (90* +/- 5*C) within a very short time.

Unfortunately, in a vast majority of cases, Owners/Mechanics/Authorised Service Centres included, continue to think out of the Amby/Fiat Era that this ‘Th-V’ is like a human appendix and has no useful purpose - other than ‘heating up’ the engine! Nothing could be farther than truth. To check whether this ‘Th-V’ is in place and in working order, here’s what you can do:

“First thing in the morning, BEFORE starting the engine after the overnight shut down, take off the Radiator Cap, keep the Bonnet open and then start the engine. Take a notch or so of the ‘Choke’ to keep it from stalling.

“As soon as the Engine fires, go across to have a look into the now open radiator neck. If you see turbulence/coolant circulation already, then your ‘Th-V’ is either not there (removed like an Appendix) or faulty (stuck in open position). If so, get it replaced at your Co. Authorised Garage.

While its being installed, as an abundant precaution, ask them to check the ‘By-Pass’ ckt. as well, to ensure it’s not blocked with sediments etc. If it is but not cleared at this stage, then with the new Th-V in place, the engine will throw-up Coolant right upto the windscreen when it warms up!

On the other hand, if the Th-V is in place and not faulty, you will see no circulation in the open radiator neck for quite some time. Then as the engine warms up, you would be able to see it setting-in ‘fits and starts’, including tendency to overflow from the neck. Just before that happens, shut-off the engine and replace the Radiator Cap properly”.

If the ‘Th-V’ is in place and working, the problem is somewhere else!

The most common possibilities are - a) The ‘Accelerator-Pump-Jet’ System of your Carb is either not working or mal-adjusted, b) The Vacuum Advance System of your Distributor is faulty, c) A ‘Retarded’ Ign. Timing and d) Your A/F mixture is set too lean (should be CO @ 0.5-1.0% for EU-I and 1.0-2.5% for pre EU-I Cars). Again it’s a common misconception that setting it ‘leanest’ possible gives you max mileage. On the otherhand, it results more in stalling when the Engine is cold.

If inspite of every thing being in place, a cold engine still has a tendency to stall - depending on Ambient Temps - then as the Owner’s Manual suggests - take a ‘notch’ or two of the choke for the first few minutes. This will not only prevent its ‘stalling’ but also help it to warm up faster. However, please ensure that you don’t forget to ‘reset’ it. If you do, you will not only be wasting fuel but also seriously cutting into the lubrication ‘film’ on the cylinder walls/engine life as well.

Next time, tho’ a lot more user friendly, we’ll talk about causes and cures of MPFi’s (BS-II/III) exhibiting such cold stalling symptoms.

Preamble
In the last couple of ‘episodes’, I’ve talked about the pros and cons of ‘premium’ petrol’s and diesel’s. So it may be worthwhile to continue the dialogue and now talk about the most vital fluid in a car i.e. the engine oil – which is rightly equated to blood in the human body.

Today’s engines are efficient and sophisticated machines, often using multiple camshafts, turbo-chargers and other features. They also run faster and hotter, placing tremendous demands on engine oil performance. That’s why it is essential to follow a strict oil-and-filter change schedule for your car.

Changing the oil and filter remove harmful contaminants that build up in your oil with usage – time wise as well as distance wise. A fresh supply of engine oil with its specially selected AND blended additives will restore the protection your engine needs against corrosion, gum deposits, excessive wear, and other problems.

The oil and filter should be changed at the interval recommended in your owner’s manual. Every 5000 km or 3 months is a common recommendation in North America. Every 15,000 to 20,000 km/year is more common in Europe. Whereas in India now, with the advent of BS-III vehicles, 10,000 km or 6-12 months interval – whichever is earlier - is the norm.

Most car owners at some time or the other face a strong sales pitch to ‘fortify’ their engine oils with well-branded ‘Additives’. While most oils look, feel, and smell the same, their designed ‘performance’ can be vastly different - thanks in part to the special additives that their formulators blend them in with. Such additives suspend dirt, inhibit foam formation, improve cold-weather flow, prevent corrosion, reduce friction, and add other desirable qualities such as long life.

While many specialty additives or oil treatments are sold separately as brand names and promise longer life or extra performance for your engine, it’s worthwhile to remember that modern oils are complete ‘recipes’ by themselves having measured portions of all their ingredients. Upsetting such a ‘recipe balance’ can and more often than not, does lead to problems.

An oil formula may include a little anti-wear additive the same way a cake includes a pinch of salt to bring out its flavour. If a little salt works, should you add more? Probably not, and the same goes for oil additives. Choosing the best quality oil you can afford and changing it according to your Owners’ Manual is wiser in the long run.

Synthetic Oils are the ‘Ultimate’ Lubricants available in the World today and to the best of my knowledge, ‘Mobil-1′ is one of the ‘official one’ in India. Regrettably, most retailers don’t stock it as it costs ~ Rs: 750/- a Lr and the takers are very few. Besides, at this cost, the chances of it being spurious are more than bright.

On the flip side, given our Operating Environment, S/O’s can easily go > 3x the otherwise recommended drain interval for the conventional Oils - time as well as distance.

The next best option I’ve come across is the ‘Castrol-Magnatec’ at < half the cost. With this, one can safely do 1-1/2 times the distance/time on the recommended drain intervals.

However, for general info, it may be noted that Synthetic Oils are not recommended for a vast majority of mass produced stock engines, new or under ‘running-in’, to enable them fully ‘bed-in’. Further, as practically all new Cars today come with Warrantees upto 2- yrs/40 kkm, during this period the OEMs don’t permit using any Oils supplied by Customers - for understandable reasons - unless your Dealer is prepared to put-in these at your cost - which he won’t!

Preamble
Last time we discussed the pro’s and con’s of switching over to the new generation/detergent pre-mixed petrols in the Mpfi vehicles, or for that matter, the equivalent/’turbo-diesel’ for diesel vehicles. Let’s have a look now as to what really is meant by ‘Fuel-efficiency’ and ‘Fuel-consumption’ of a Vehicle – suffice to say that they are NOT the same…

The real life ‘Fuel Consumption’ of any vehicle is one of the most controversial issues and at the outset, I’d like to drive home a point that no where in the world can these figs be guaranteed. At best these can be taken as ‘indicative’ only.

For starters, ‘traffic-movement-wise’, can any one define what’s a ‘City’? If you have been to some of the Metros like Delhi, Mumbai and Kolkatta, you’ll know. Over and above these, traffic jams can hit you anywhere out of the blue. Therefore, same Car with the same driver on ‘up’ route will show one level of FC and another on the way down ‘down’!!

Btw, all Cars today are more or less equally ‘Fuel-Efficient’. Their actual ‘Fuel-Consumption’ depends on the ‘Bhp’ you demand out of them - by way of acceleration, cruising speed, AC etc - which in turn depends on their ‘Kerb-Weight’ and the ‘CC’ of the Engines they have.

Waiting at Traffic Lights:

It may come as a surprise to know that it’s wasteful not only of fuel but also from wear and tear considerations on one’s Battery AND Starter Motor - to switch off the engine if the wait is going to be less than 2-mins - which generally it is.

Pick-up or ‘Mileage’!

According to reliable road test data, these for the two popular ones are as below:

Santro: 0-60/100 kph = 5.55/14.66 secs @ Highway kpl of 16.2. (3-Valves/Cyl; 1086cc)
W-R: 0-60/100 kph = 6.31/16.60 secs @ Highway kpl of 16.2. (4-Valves/Cyl; 1061cc)

From these fig’s, it can be seen that the first engine having lower # of valves AND higher ‘cc’ accelerates faster than the other one having higher # of valves/lower ‘cc’, to deliver the same/highway fuel ‘consumption’. The point I’m making here is that in these days of ‘MPFi’ tech., it’s a child’s play to get acceleration and FC figs as one likes - within overall limits of course.

Speed vs ‘mileage’:

Let’s take the example of an MPFi Zen/since phased out. It could easily do 21 kpl @ 60-70 kph and 18+kpl at speeds of 100+ kph on a highway.

This is quite normal, for it’s a well known fact that wind resistance goes up with speed in a complex manner - starting with square of it and going upto the power of 4 - depending on its magnitude.

In other words, say at a cruising speed of 50 kph, 40% of the engine power goes towards over coming the vehicle’s ‘rolling resistance’ and the remaining 60% to overcome its ‘wind resistance’. Assume these as 5 and 7.5 = 12.5 Bhp.

Further, assuming that the rolling resistance remains more or less constant beyond 50 kph, at 100 kph the engine will have to produce 5 + (7.5 x 4) = 35 Bhp. So as far as the engine is concerned, for 2x the speed, it has to produce 3x the power.

Therefore, in terms of ‘Specific Fuel Consumption’ which is defined as ‘grams per Bhp per hour’ - that’s how the engine sees it - its FC stands to go up by 3x but then, at 2x the speed, it also has to run for half the time to cover the same distance - or effectively the FC stands to go up by 1.5x to cover the same distance. In other words, if it was doing say 25 kpl @ 50 kph, at 100 kph it stands to do ~ 17 kpl.

And mind you, the ‘SFC’ that we just talked about above also varies with the absolute Bhp demanded from it coz an Internal Combustion Engine’s ‘fuel efficiency’ drops above and below its ‘peak torque’ rpm.

Further, since an ICE’s max rpm AND Bhp is limited, 59 Bhp in this case, it follows that at 100 kph, it’s got only 59 - 35 = 24 Bhp left to propel it any faster and going by the above relationship, this will get used up by another 40 kph or so - leading to its top speed ‘capability’ of ~ 140 kph.

To sum-up, to get the best ‘FE’ (as opposed to absolute Fuel Consumption/kpl) out of your Car, cruise as close to its peak torque rpm as practicable.