Turbo operation depends on engine speed, not road speed

Hi Baraza,
I have learnt a lot about cars through your column, thanks. I own a Lancer Cedia wagon 2001 model that has a GDI and turbo 1830cc engine. I like it because its pretty powerful compared to my bro’s “flimsy” Toyota Fielder.

Now, If I may ask:

1. I was told that the turbo will kick in only beyond 80km/h, and only if I use a particular type of fuel, is this true?

2. The car has a small delay between the time the accelerator pedal is pressed and when the car actually responds (about half a second), what could be causing this?

3. I use 5W oil for the engine as I was instructed that its the best for this car, is this okay?

4. There was a motorist in one of your columns who claimed that his Subaru Forester (2000cc) can do Nairobi to Thika and back on Sh1000 worth of fuel; I do not think my car is consuming a lot of fuel but I also know it cannot do a thousand bob for that distance, yet its lighter and has a smaller engine. How can I verify that its consumption is okay? A diagnostic was last done in August and it came out clean; the consumption hasn’t changed since then.
1. No and no. The turbo operation is dependent on engine speed, not road speed, so watch the rpm instead of the km/h. For proper boost achievement, keep it boiling at 3500rpm plus, but get ready to pay through the nose for fuel. Speaking of which, provided you have put petrol in the car and the engine is running, the turbo will work. Let no one lie to you that one particular brand of fuel will activate the turbo while another won’t.

2. The delay could be caused by turbo lag or a faulty throttle sensor. My money’s on the lag.

3. The 5W sounds a bit inappropriate and just a touch worrisome. We do not need a winter-use oil in these climes, and the low viscosity index means that the oil changes viscosity rapidly with heat; and if there is one thing in plenty from a turbo engine, it’s heat. But if the 5W is for kinematic viscosity, then that is what you need, to allow the oil to seep into the turbo workings properly. If I were you I’d try maybe a 10W, or 15W.

4. I have said repeatedly that driving style is the biggest contributing factor to fuel economy, though, at Sh 120 a litre and given the kind of traffic conditions that prevail on Thika Road, our Forester couple may or may not have been making their trips at 3am when everybody else is asleep. So if the diagnosis says your car is okay, and your car looks, sounds and feels okay, then it is okay.

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Hi Baraza,

I have an automatic 2009 X-Trail which I bought two years ago. Could you please tell me its advantages and disadvantages? Also, please tell me how much horsepower it has… and if its ugly or not.

You do not know if your car is ugly or not? Have you seen the car in question or is this hypothetical? Anyway, I like the X-Trail’s external looks, it is very handsome.

In fact, I think it is one of the best looking cross-over utilities (eat that BMW X3, you ugly thing!). I don’t care much for the interior though.

Here are the power figures:

2.0 Petrol: 103kw/134hp @6000rpm, torque – 192Nm @4000rpm

2.0 Diesel: 110kw/143hp @4000rpm, torque – 320Nm @2000rpm

2.2 Diesel: 84kw/112hp @4000rpm, torque – 270Nm @2000rpm

2.5 Petrol: 132kw/176hp @6000rpm, torque – 245Nm @4000rpm

These figures apply to all 2004/2005 cars, except the 2.0 Diesel, whose figures also apply to the 2010 model.

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Hi Baraza,
I have a Subaru Legacy GT Twin Turbo and have three queries:

1. Is there any specific engine oil type for this model (I prefer synthetic oil)? What about spark plugs?

2. I went for greasing and was told Legacies cannot be greased unless the wheel mechanism is removed. Now is there a grease type that can last around six months for this type of car?

3. If the spark plugs are overused, is fuel consumption going to be on the higher end? What are the signs of over-used spark plugs?

1. Synthetic oils are recommended for turbocharged engines, so you are bang on the money on that issue.

2. Does the car need greasing? If yes, then go ahead and grease it. Forget about wheel mechanisms and time lines.

3. Fuel consumption will definitely go up. Signs of dying spark plugs include misfiring, a notable drop in power and the smell of unburnt or poorly combusted petrol coming from the exhaust.

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Hi JM,

I want to buy a small car which is not thirsty (1000cc to 1300cc) but with good space and good performance. I had the following cars in mind: FunCargo, Platz, Vitz, Duet (all Toyotas) and Mazda Demio. Which one of these might be the best, something I can own for over five years?

Mulwa

Go for the Demio. It is the roomiest, followed by the Platz (boot space) and/or FunCargo (headroom, rear legroom). Forget the Vitz.

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Hi Baraza,
I am an automotive technologist and would like to help you out on the question by Juma (DN2, December 14, 2011) on the red button on auto gear levers. It’s actually used when trying to shift to neutral in case you would like to push or tow the vehicle if you do not have the key. Normally, you cannot shift if the ignition is not turned on and the brake pedal depressed. The little red button helps you avoid all this.
Cheruiyot

Okay, thanks for the heads up, Cheruiyot!

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Hi,
I am a great fun of your column. Now, I have an interest in the BMW 116i, kindly advise me on its mechanical reliability of suitability in this region. According to some online reviews I have read, the fuel efficiency of the car is quite okay at 4.8l/100km.

Isaac

At 4.8l/100km, that must have been the 120d. Why do you want a 1-Series? The only reason anyone would buy a 1-Series is for performance ONLY, because it is unnecessarily expensive, its rear-drive chassis means rear seat space and boot capacity are a joke, and it is not exactly a looker. If I was to buy a 1-Series, I would go the whole hog and get me a 130i.

Mechanical reliability? Well, it is a BMW, so it will not fail easily, but when it does, expect the usual tear-jerking repair bills. Pertinence to the region? As a developing country, our choice of cars is quickly turning to personal preference rather than mechanical capability as was the case previously.

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Hi Baraza,
I have a 2002 Mitsubishi Cedia wagon, 1800cc, 4WD tiptronic. My nightmare started when it stalled and the gear indicator on the dashboard started blinking N even after shifting to D or R. I hopped from one mechanic to the next and all of them told me to buy a new gearbox. One even told me to write off the car. Finally I got one who fixed it by replacing a chain in the gearbox and a sensor.

One month ago it started making some really loud noise from the left side and stalled 10 metres from where it started making that noise. The mechanic did a diagnosis and found it was the 4WD gearbox that had broken down; the main gearbox was okay.

I had to replace the whole gearbox plus the pressure sensor (and it wasn’t cheap at 110k). It took a while to find it because, apparently, Cedias are not that many on our roads and they haven’t been in accidents enough to get parts from their write-offs, so spares are rare and expensive.

After changing the gearbox, there was some other noise; this time, the flywheel had cracked. I changed that. Now, when starting the car there is a noise that sounds like stuff banging against each other in the chassis. This goes on for a while then goes silent when the engine warms up.

When the gear lever is on N it’s silent, but on R or D its there even when I engage manual. The car also vibrates when at idle on D but not on N.

My mechanic tells me he has changed the engine mounts, so I’m at a point where I am thinking writing it off would have been a better solution. I need your insight here. Saidia!

Caroline.

Unfortunately, not even I would have had the foresight to tell you to get the entire transmission system overhauled — starting from the clutch to the primary gearbox, transfer case and shafts — had you come to me with the problem earlier.

The damage the transmission suffered earlier could have warped some of your drive shafts, hence the noises and subsequent failures.

Either that or, after the 4WD system, chain, sensor and flywheel, your clutch is now taking cue and packing up too.

Writing off the car sounds extreme but, with six-figure repair bills, I can see where you are coming from. It might be the wisest move at this point.

You could scrap the car. Sell it in bits. To avoid getting short-changed, go to the shop, ask how much a part costs (as if you want to buy) and then offer to sell them the parts at that quoted price or slightly lower. See what they tell you…. It might help you recoup some of your losses.

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Hi Baraza,

Please enlighten me on the following:

1. Is there any performance change when wheel sizes are altered?

2. What is the allowable extent of adjusting wheel sizes (plus one or plus two inches of what the manufacturer gave)?

3. Is it true that the main effect of changing the wheel diameter on a car is the need to change the gears, which change the ratio of engine speed to wheel rotation speed?

4. Is it true that larger wheels rotate more slowly for a given car speed?

5. Is there any (even the remotest) possibility of compromising stability and therefore safety of the vehicle by replacing smaller manufacturer-spec wheels with larger ones?

May 2012 be yet another good year for all motoring enthusiasts through your column.

1. Yes, such a change will definitely affect the car’s performance.

2. It is wise to follow the manufacturer’s recommendations, but the available space within your wheel archs will guide you too.

3. Not the “need”, but bigger wheels do have an effect of gearing up the transmission at tyre level. The bigger the wheels, the more noticeable the effect.

4. Yes, they have a lower angular velocity. Speed= Distance/Time, so for bigger speed, you have bigger distance (circumference of the tyre) and constant time.

5. It’s a definite yes, not “a chance”, outsize tyres will definitely corrupt the manufacturer’s settings.

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Hi Jim,
What is your opinion on the Mercedes ML class? The used models are mainly available in the ML 280 and ML 320 diesel versions, what’s your take on them? The few reviews I have read have ranked the M5, Q7 and Range Rovers higher. Although I like the classy looks, Range Rovers are rather ubiquitous locally. I shall be much obliged to hear your views.
Eric

Not a good car. Heavy, ugly, the diesel versions were not Daimler’s finest moment and the car was built in America for Americans, so built quality is dodgy and panel gap consistencies are measured to the nearest foot. The AMG version is an overweight, over-thirsty pointless exercise. The M5 is a saloon car and does not belong to this group.

The Q7 is not that good either; it has a woeful turning circle, is extremely heavy and, as such, the engines are overworked and fuel consumption suffers. But it has the best interior in the world.

Oh, and my name is not Jim.

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Dear Baraza,

I own a Toyota K70 saloon car. The vehicle was manufactured in 1980, but registered in 1983. I have christened her ‘Historic’ because there are very few of them remaining on the road. The vehicle is very intact.

Having had two previous owners, it has done only 110,000 kilometres and still wears authentic Firestone tires of old. Since it was manufactured, according to my mechanic, the clutch had not been charged and this was done only this year when some young adults I was teaching how to drive a manual burned the clutch (whatever this means!).

The engine still bears the manufacturer’s nuts and bolts as it has never been opened (I have only changed the fuel pump after some malfunction). Though it has a carburettor system, it does about 12 km per litre (is this good? Can it do better?) and have travelled immensely with it going to far off places like Eldoret. Spares, though Taiwanese, are available both in Kirinyaga Road, Industrial Area or even Kariobangi.

I normally find your answers quite straightforward and realistic, so I pose this question: Do you have something good (or bad) to say about this small vehicle? Something that can justify my holding onto this old relic that went out of production many years back? Please let me know, in your own honest way, the good, the bad and the ugly of this vehicle.

Lawrence

Congratulations on two fronts: One, now I can relax knowing I am not the only one out there still flogging carburettors, and two, honestly, congrats on a car well kept. But I think you may have to change the tyres sooner rather than later.

For any car, 12 kpl is quite good, let alone one with a carburettor. And the K70 can do better, but you’d rather not because this means resorting to some funny techniques, not all of them sensible or legal.

By all means, keep your car. I don’t see why you would want to sell it, given how you have gushed about it and extolled its virtues. It is something special given that it has survived to its current age and in its current condition, and it is a show of just how well you can maintain your car.

Again, congratulations!

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