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Car (South Africa) - - CONTENTS -

JERK­ING POLO

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.

DIRTY IN­JEC­TORS?

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.

AU­TO­MATED MAN­UAL

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.

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