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I am hoping you can impart some knowledge. I have taken my 2003 Polo Classic 1,4 to numerous mechanics (including Volkswagen), but no one can fix the issue. The car jerks in all gears while cruising or accelerating. I’ve changed petrol and air filters, spark plugs, replaced two coils and disconnected the exhaust-gas recirculation valve. Mechanics say it is not the throttle body, so they don’t know. The problem is worse when it rains and the EPC light comes on some times. Any ideas, as I have lost faith in the technicians? MARK WILSON Email When the EPC (electronic power control) light is lit, it means the ECU has found a problem with one of the powertrain sensors or systems. Best is to take the car for a diagnostic scan so the trouble codes can be read to pinpoint the problem. The most common faults related to the EPC light is a faulty mass-airflow sensor (MAF), faulty throttle-position sensor (TPS) or even broken engine-speed sensor. Obviously, the codes are the best way to go but our guess would be the MAF. See if you can swap one with a friend who has the same model and test if it solves the issue before buying one.
Unfortunately, a jerk can be a result of many problems. It’s mostly fuel or spark related and it’s best to identify which one before investigating. Spark can be coils, plug leads, spark plugs, etc., while fuel can be fuel pump, fuel filter, water in fuel, or the ECU not supplying fuel because of a faulty sensor, as explained before.
I took my Mercedes-benz 220 CDI for its 140 000 km service at the dealer. The technicians showed me a picture of the state of the injectors, advising they need cleaning or replacement due to sulphur build-up. The estimated cost was a jaw dropper. Is the need for injector cleaning not picked up by the diagnostic system (an engine light) or erratic engine performance? THEMBA MAHLALELA Mbabane We are surprised the dealer suggested injector cleaning after a visual inspection. Did they remove the injectors, as this is not normal service procedure? The injector holes are microscopic and it is impossible to spot with the human eye whether cleaning is required. The only way to scientifically prove this is the problem is on an injector-flow bench, a very costly but accurate measuring tool.
Modern diesel has additive packages designed to clean the injectors as you drive, so it should never be a problem. If the car is running fine with no excessive smoke (or bad fuel consumption), we would not worry about the injectors.
I’ve just taken delivery of a Suzuki Swift GL with an automated manual transmission [AMT; similar in operation to the unit employed in the Renault Kwid]. I find the action of this type of transmission unacceptable. Could you perhaps explain why manufacturers choose this auto technology instead of CVTS, torqueconverters or even dual-clutches? Also, do you think AMTS will be trouble-free in future? DAVID MCKINNEY Rondebosch Many people would agree an AMT is an acquired taste because of its slow and cumbersome operation. The main reason to use this technology is cost. It is cheaper to
develop a mechatronic unit (robot) that bolts onto an existing manual transmission to carry out the shifting and clutch operation than develop a whole new transmission.
We have not heard of any issues with the latest versions but they are still fairly new to our market. Let’s hope these transmissions are not as troublesome as the firstgeneration Alfa Romeo Selespeed units, for example.
GOLF OIL CONSUMPTION
I own a VW Golf 7 1,4 TSI with an oil-consumption problem. The car has done about 180 000 km, most of it on highways. I’ve never encountered such a problem before due to the predominantly cruising speeds I do because of my work. My cars are usually still in perfect nick at the roughly 200 000 km point when I start looking for a new one.
The current oil consumption is about 0,5 L/1 000 km, which the car’s handbook states as normal. The problem started just before the 120 000 km service.
I have since been advised this seems to be a common quirk with the 1,4 TSI engine and that stuck oil rings are to blame. The car has a full franchise service history. I had the oil tested by a tribology facility but, since I have to top up the oil so frequently, it was too clean to reveal any problems. My questions are: 1. Is this normal? 2. Wouldn’t the oil consumption contaminate the lambda sensors and catalytic convertor over time? 3. Is an engine overhaul the
only solution? 4. Can an engine flush help to
release the rings? 5. Why does something like this happen to an engine meticulously cared for? RUDOLPH STEYN Pretoria To answer your questions: 1. Most OEM warranty limits are 1,0 L/1 000 km, above which they’re obliged to fix the problem. In our opinion, even
0,5 L/1 000 km is excessive. 2. It would definitely not help the cause but, in our opinion, the amount is still too low to cause terminal damage. 3. The term engine overhaul is a vague one because, in the old days, it meant new bearings, oversized pistons and rings, new valve guides, skimmed top, etc. We would propose you rather do a few simple checks to establish how the oil is getting to the combustion chamber, which may include a compression and leak-down test; blow-by check (combustion gases out the breather pipe of the engine); investigating the intercooler for oil from the turbo; and checking the valve seals/guides etc. The normal culprits for oil consumption are worn piston rings and cylinders; worn valve guides and seals; or turbo problems. 4. Unlikely. 5. We agree it should not happen
with a well-maintained engine.
Maybe it overheated slightly at some point without you noticing, or the tolerances in this specific engine lead to more wear than usual, but this is all speculation. We have not heard of oil consumption issues with the 1,4 TSI but we have heard of problems with the Audi 1,8 and 2,0T FSI units that are well documented and some issues with the 1,4 twin-charged (turbo- and supercharger) engine fitted to other models.