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Why do Touareg common rail engines require more care?

Hi Baraza,

Thanks for your informative page in DN2. Two quick questions:

1. What is the meaning of “common rail engine” in VW Touareg?

2. Why do vehicles with a common rail engine require more care than other engine types?

Thanks in advance,

Charles

1. The common rail feature in an engine is a type of direct injection fuel delivery system involving much higher nozzle pressure (up to 1500psi) as compared to what used to be called direct injection (but nowadays distinguishable as pump-duse) in which a fuel pump serves unit injectors.

In a nutshell, common rail works like this: there is a fuel rail which serves all the cylinders (hence the name common rail). Fuel is delivered into this rail at very high pressure to enable easier and more efficient atomisation of fuel.

The injectors in each cylinder are fed fuel from this rail and while early versions of common rail engines used mechanical actuation of the injectors, more contemporary engines use solenoids and piezoelectric valves (piezo electricity is created by pressure or impact). This electronic activation enables the fine tuning of injection pulses and fuel quantity for more efficient running.

Look at it this way: You have a line of houses. On one end is a water reservoir. The water is delivered to these houses by a main pipe running past all the houses into which water from the reservoir is forced, either by a pump or by gravity. Each house has its own pipe connected to the main one, and these pipes terminate in the taps inside the house and these taps are opened by the house occupants every time they need water.

The water reservoir is the fuel tank. The main water pipe is the common rail. The individual house pipes are the injectors, and the taps are the injector nozzles. The solenoids or piezoelectric valves are the people who open these taps at the time of need.

To put things in perspective, we need an analogy for the pump-duse system. We still have a water reservoir on one end of the line of houses, but in this case each house has its own pipe going straight to the reservoir. In pump-duse, we have what are called unit injectors, combining an injector nozzle with its own injector pump.

Fuel reaches each unit injector by means of ducts machined into the cylinder head. Since the unit injector has its own injector pump, fuel arriving at the injectors is under lower pressure; pressurisation for atomisation is done by the injector pump. This is unlike common rail, where the fuel has to be pressurised while still in the rail.

Each system has its pros and cons, but these are becoming trickier to justify or dismiss as electronic systems take over more and more control of vehicle systems, but as it is, common rail engines are more the norm for both petrol and diesel engines.

2. I would not say common rail engines require “special” care compared to unit injection engines, but given that pressurisation of the fuel starts at an earlier stage, then it is harder to isolate a fuel pressure issue in case one of the injectors gets clogged or cracks (a very unlikely occurrence).

Also, the unit injectors are cooled and lubricated by the fuel itself, eliminating the need for these additional systems. And there is no need for high pressure fuel pipes, reducing risk of pressure-associated problems.

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Hallo Baraza,

I recently acquired the latest Toyota Premio model in the market but I have an issue with my eldest son, who apparently has forged a spare key.

I fitted the car with a secret switch but he discovered it. Disconnecting the battery does me no good. Can you advise me what I could disconnect to prevent the car from igniting?

Eric

What you need to do is confiscate his key and teach him the importance of respecting other people’s property. However, mine is not a parenting column, but a motoring one.

If he found the first cut-out switch, then most likely he will find any others you may choose to install. So it might be time to do things the way Mr Bean does because the situation is desperate. Remove and hide the battery in a different location. This is very tiresome and risky because some cars actually need the ECU (electronic control unit) to be mapped again if the battery is removed.

You could also fit a padlock-secured dead bolt on the driver’s door, but this will tarnish your car’s otherwise pristine appearance. How about a steering lock? Or gear lock? Or both? Aftermarket high-strength steel affairs that are also key operated and are hard to pick open.

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Hi Baraza,

I have a question concerning the Toyota IST 2005 model 1298cc. Is it possible to change its gearbox from automatic transmission to manual transmission? I am used to manual transmission as it gives me more control compared to automatic transmission, where gears shift on their own.

What implications will it have on the overall performance of the vehicle? Will it affect the vehicle negatively or positively and what are the costs of acquiring and replacing the transmission system?

Max

It is possible to swap an automatic transmission with a manual one. Performance implications are dependent on the ratios in the new gearbox, but the general prognosis is good: it should improve, if not for anything then for the use of a friction clutch and a lighter transmission.

If the transformation is done properly, then your car will not be negatively affected. The exact costs of acquiring and replacing the transmission are unknown to me but what I know is that some of this can be off-set by selling the auto-box. That way the net cost will be low.

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Hi Baraza,

I am a mechanic and regular reader of your column. I own a Peugeot 504 pick-up and its consumption was terribly excessive. I modified its carburettor and it now drives at 13km/ltr.

My questions are:

1. Can I sell my idea to global manufacturers? And how can I contact them because I have tried it on the Internet but it is complicated.

2. Do you think this idea can bring carburettor vehicles back in the market?

3. Can manufacturing a complete product and selling it locally be marketable.

Innovative Mechanic

1. You can sell your idea to global manufacturers, but whether they will actually buy it is a matter of conjecture. I cannot speak for them and I do not know how good your idea is (I am not being nasty, but for all I know you could be using a smaller jet in the carburettor to reduce fuel consumption. Also you have not clarified if your modification has any implications on power or torque).

Contacting them is complicated, mostly because none of these people are based in Africa, let alone Kenya, and ours is an irrelevant market so they are not likely to get excited about news from this corner of the world. When I say ours is an irrelevant market, what I mean is that we do not buy new cars in numbers large enough for our opinion to matter on the world stage.

The only manufacturers whose ears I have (internationally, not locally) are Jaguar-Land Rover, General Motors (to a small extent), and hopefully Mahindra by the end of the month. I cannot promise to push your idea forward you because my line of work does not allow me to: it will conflict with my objectivity/neutrality.

2. To be honest, no. Carburettors, while cheaper, have been superseded by EFI (electronic fuel injector) systems and are, thus, crude by virtue of design.

3. This calls for market research and analysis before a decision or solid answer can be arrived at, which is a whole other line of work.

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Hello Baraza,

I am a regular reader of your column. Being a woman, I am very concerned about my tyres. I need your advice on the best tyres in the market.

I drive a Nissan B14 and one of the tyres has been losing pressure at a high rate. My mechanic checked for any punctures but it does not have any.

Luckily they are tubeless, but every week I have to make sure that they have enough pressure. And since I do not want to have any issues, I want to replace two of them. What would you recommend? I am looking for quality and value for my money. I am not sure what brand my current ones are as they came with the car when I bought it.

Miss Problematic Tyres.

If the tyres themselves are fine, then the valves/nozzles are leaky. One of the cars I use on a regular basis actually has that problem, but on a smaller scale in that I do not have to check the tyres weekly.

I would say replace the valve (the teat-like thing that one uses to pump up the tyre) but this is not as easy as it sounds and it could actually ruin an otherwise serviceable tyre. Another word of advice that I may give but not fully stand behind is to “grin and bear it” — Pump up those rubber rings weekly.

Now, sadly for you, I cannot do product endorsements right now. It calls for very extensive research, which no one seems interested in funding (but I am very interested in actually doing it) and if I fund it myself on my current salary, then I will die a debt-ridden and bankrupt man. I have not given up on that quest yet, though.

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Hello Bwana Baraza,

I own a Toyota Corolla 110 but I intend to buy a new car at the end of this year, God willing.What is your preferred choice between Toyota Noah and Toyota Wish?

I personal I prefer Wish but my wife and children prefer Noah. Their happiness is my priority. Your quality advise will be highly appreciated.

Best regards,

Nassir

My preferred choice? That would be the Noah, for two reasons: the Noah offers more space and practicality, but more importantly, there is no love lost on the Wish from me, not for any solid reason except that it is a bit unsightly and is used (mostly) by those with over-productive loins. Mostly. Not always.

The Noah still wins either way because you have actually answered your own question. You say your family’s happiness is your priority, and your family has a thing for the Noah. So make them happy and get a Noah.

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Motoring news this year

The Sky Has Finally Fallen

It is all doom and gloom along Lusaka Road as CMC Motors woke up to the shocking news that Jaguar Land Rover is no more.

No, the Indian-owned British corporation has not closed shop, but as far as CMC Motors are concerned, Jaguar and Land Rover cars may as well not exist beginning February 2013, if the world does not end in two week’s time.

CMC’s contract expires then (Feb), and it will NOT be renewed. I bet some individuals there wish the world would end this month, after all….

In a statement released to members of the motoring press all over Africa, one Willem Schoeman of JLR SSA (Jaguar Land Rover Sub Sahara Africa) made it clear that JLR as a company has high hopes for Kenya; only these hopes are tied to another company; one that few people have heard of: RMA.

It was not so much we don’t want CMC as it was we want RMA. These sentiments were echoed within the Tweet-verse and the blogosphere, the difference being that while JLR’s statement was more pro-RMA than anti-CMC, Internet opinions were the other way round.

“It has been a long time coming…” one of my Twitter followers chirped. “It is about time…” piped another. “Good riddance…” said a third. Hard times, these.

“Jaguar Land Rover is pleased to announce the appointment of a new partner in Kenya, the RMA Group,” thus quoth Herr Schoeman.

If a lady announces she is pleased to have a new boyfriend, more often than not that means the incumbent/outgoing squeeze was not up to scratch and was therefore relieved of his duties. I don’t know if this also applies in the corporate world.

“The RMA Group brings a broad range of expertise and experience in the… industry… with the (JLR) brand, which they currently represent in other global markets.”

( My new boyfriend is an accomplished lover and is way cooler; and all his old girlfriends still have the hots for him). These are not very encouraging words to be reading when one is being replaced: whether as a boyfriend or as a franchise holder.

On a more serious note: this is not a time to celebrate for the motoring giant (CMC, I mean, not JLR). JLR is on a roll, releasing new products faster than we can write about them, and now is not the time for anybody to fall off their wagon.

The 2013 Vogue has been received with rave reviews and plenty of excitement worldwide. There are updates for the two Jag saloons: the XF and the XJ.

There was the Discovery 4, and the Evoque not too long ago, the Freelander has just received its 2013 model year refresh, there will be an all-new Defender in the not too distant future, the long awaited Jaguar F Type is slotted for release next year, there should be an all-new Range Rover Sport somewhere within sight also….

Now is really not the time to get oneself fired, in a Trump-esque, Apprentice-style send-off.

You may have noticed that the word “surprise” does not appear anywhere in the preceding writing. This is because whispers and hints of the looming break-up reared their unseen heads as far back as September.

Back then, the grapevine had it that, first, CMC and RMA were to share the franchise, with RMA being primary importer. Then it became a contest as the two vied and jousted for the new contract (still on the grapevine, and thus unverifiable). Now word from Mzanzi is that CMC will not be selling JLR products much longer. This much is verifiable.

What Herr Schoeman’s missive doesn’t explain is exactly why CMC Motors have been kicked to the kerb in favour of RMA. The signs were there though: scandals – 1. the head honcho earning a bigger salary than the entire company’s profits, 2. his replacement being on the receiving end of some dirty, underhand maneuvers in an attempt to keep him and his whistle (which he blew very hard) away, 3. the disappearance of (of all things) an ex-President’s Range Rover car…

This, by the way, had been nearly forgotten until the vehicle surfaced several years later (a few weeks ago) in the hands of yet another high-profile individual, blowing the case wide open again.

An insider also confessed to yours truly that they were unable to move units in sufficient numbers, so the company depended heavily on maintenance and service of Range Rovers for the department to make money. Clearly all has not been rosy at the country’s biggest motoring franchise for a while.

It was good while it lasted, CMC Motors. Hold your heads up and work towards a brighter future. RMA: you have your work cut out.

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2013 Freelander

Still on matters Land Rover: The Freelander 2 has been updated for the 2013 model year. Cosmetic surgery has been done to great effect so that the new car looks much better than the outgoing one.

Not that the predecessor was ugly to start with, but it takes fresh input to put things in perspective, and the perspective is that the Freelander Two-And-A-Half is out in full force to threaten the competition which had been catching up.

Freelander 2.5, you ask? Well, yes. The changes are not just skin-deep. New engines and new transmissions appear too. The Evoque’s engines to be exact: the 2.0 litre petrol Si4, the 2.2 litre diesel SD4 (which we will get, good for 140kW/182bhp) and the 2.2 diesel TD4 (110kW/143bhp, which we will not get, and is also not found on the Evoque).

All are turbocharged 4-cylinder units: the 3.2 litre V6 is no more (boo!). The engines come attached to a 6-speed automatic gearbox with Tiptronic override. A new body, new engines and new transmissions: that sounds like a whole new car to me, but JLR says its is not the Freelander 3, so Freelander 2.5 I will call it.

The car is semi-skilled off-road (not that many of you will be driving it on cliff faces or underwater anyway), it is fine on road, with a floaty feel from the steering at speed.

In an odd turn of circumstances, the petrol engine is ok, you could even call it a bit special, but the diesel is a mite underwhelming in performance and response.

Weird, considering how diesel versions of a car are usually made to outshine the petrol version in order to boost sales. Couple this to a dim-witted automatic and it is easy to see which spec will win hearts: the petrol version, which you will most likely drive in Tiptronic mode 85 per cent of the time.

Expect the car to cost anything from Sh5 million upwards once it hits the showrooms next year.

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Nissan Qashqai

The-Nissan-with-a-name-that-cannot-be-pronounced has just been “launched”. This is despite its making an appearance in several local shows and displays, including DT Dobie’s own previous other-vehicle launches.

Quite a launch this particular one was though, featuring well-heeled senior corporate suits, finger food, fruit juice, paint guns and graffiti. I don’t know what effect DT Dobie was going for with this ensemble.

The Qash-and-Qarry continues Nissan’s recent tradition of unleashing slightly underpowered vehicles on an unsuspecting public (Tiida, Almera). 136bhp and 20kg.m are nothing to write home about, especially for a Kluger-sized car; when a mid 2000’s Honda Civic Type R hatchback has better outputs.

To sum up the irony, DT Dobie used words like “dynamic” and “distinguished” when they introduced the already familiar motor show prop. Interestingly enough, a sizeable portion of my Internet disciples detest this car.

The Nissan Qwerty can be had with 2WD or 4WD. It can be had with 5 or 7 seats. It can be had in black, or silver, and maybe in some other colours too. But there is no escaping from the 136bhp 2.0 litre “powerplant”. DT Dobie also says they sold out their initial stock, which took an entire year to accumulate.

Methinks either they are taking liberty with facts or that “stock” consisted of only three cars, because I kid you not: I have not seen a single Cash-Guy on the road. Maybe I’ve been driving on all the wrong roads….

The Nissan Quash-Key costs Sh3.6 million (more, if you spec it up). If and when I do a review on it, we will decide whether this Qar will be a Qlever Investment or a Nissan Waste-of-Qash.

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F30 BMW 3 Series

Another new vehicle release (in Kenya, at least) is that of the F30 BMW 3 Series. The front looks shark-like, which means it looks like the former 6 Series. The rear looks like just like it did on the outgoing car. I have not driven it yet, so for now that is that.