Dish­ing the dirt on fuel-in­jec­tion clean­ers

Winnipeg Free Press - Section F - - AUTOS - JIM KERR

QOne item you have touched on in the past, but to my me­mory, not specif­i­cally this ques­tion, is ad­di­tives — fuel-in­jec­tor clean­ers. I’ve re­ceived con­flict­ing opin­ions on the mat­ter even from re­li­able sources. Our gaso­line has a blend/mix­ture of ethanol, up to a 90/10 per cent. I have been told it is not nec­es­sary to add fu­elin­jec­tor cleaner as the ethanol acts as a cleaner. I gen­er­ally added the fuel-in­jec­tor cleaner just prior to an oil change (ap­plied the cleaner at ev­ery 4,500 kilo­me­tres). May I have your view on the mat­ter, please?

— Don

AN­SWER: Ethanol will clean out the var­nish and gunk in­side a gas tank, which can then plug fuel fil­ters, but doesn’t re­ally clean dirty in­jec­tors. Dirty in­jec­tors are not re­ally plugged with dirt. Rather, they be­come gummed up and sticky so they don’t open and close prop­erly or spray the fuel in a fine mist. The gum de­posits are formed as liq­uid fuel at the in­jec­tor tip evap­o­rates when the en­gine is shut off, leav­ing var­nish be­hind.

Ve­hi­cles that op­er­ate mainly on the high­way have higher fuel-flow rates through the in­jec­tors that help keep in­jec­tors clean. Slow-speed driv­ing, idling and short trips will cause de­posits to build faster. Gaso­line does con­tain in­jec­tor-clean­ing ad­di­tives, but many con­tain only the min­i­mum amounts spec­i­fied in the stan­dards. Oth­ers con­tain much more. Shell fuel, for ex­am­ple, con­tains three times the min­i­mum spec­i­fied amount of in­jec­tor-clean­ing ad­di­tive in their fuel.

Even so, there are times when adding fuel in­jec­tor cleaner to the gas tank can be ben­e­fi­cial. If your fuel econ­omy starts to drop, if the en­gine takes more crank­ing to start, or if you feel a slight hes­i­ta­tion when ac­cel­er­at­ing, you may ben­e­fit from adding an ad­di­tive to the fuel tank. One con­tainer of ad­di­tive to a full tank of fuel is enough. Don’t add more, as too high a level of cleaner ad­di­tive could dam­age fuel-sys­tem parts. You can add some with each fill, or only oc­ca­sion­ally. Some own­ers never add any and rely on the ad­di­tive in the fuel.

Driv­ing pat­terns, en­gine de­sign and fuel-sys­tem de­sign all have an ef­fect on the amount of in­jec­tor de­posits that form. Con­cen­trated in­jec­tor cleaner can be run through the in­jec­tors us­ing pro­fes­sional equip­ment at re­pair shops, and some­times this is nec­es­sary if the in­jec­tors are badly gummed-up, but adding some to your fuel tank on an oc­ca­sional ba­sis will help keep them flow­ing prop­erly.

QUES­TION: I have a ’02 Monte Carlo with a “whump­whump” noise in the front at 60 to 70 kilo­me­tres per hour. It has a V6 en­gine. When I turn left the sound goes away. Turn right and it gets louder. The ABS light and trac­tion­con­trol lights are on in the dash. An OBD 2 scan tool says “no trou­ble codes stored in the com­puter.” I re­placed the right outer tie rod, had a four-wheel align­ment and re­placed the right wheel bear­ing-hub assem­bly. It still has all the same symp­toms. Any ad­vice? — David AN­SWER: The symp­toms sound like a wheel-bear­ing prob­lem. You were on the cor­rect track when you re­placed the right wheel bear­ing, but you should have re­placed the other side. You should think of the load changes on the ve­hi­cle dur­ing a turn to di­ag­nose this prob­lem. When you turn right, the weight trans­fer is to­wards the left side of the ve­hi­cle, plac­ing more load on the left wheel bear­ing, and the noise gets louder. When you turn left, the weight trans­fers to the right side of the ve­hi­cle, tak­ing the load off the left wheel bear­ing, so it be­comes quiet. Re­place the left wheel bear­ing and the noise should be gone.

As for the ABS and trac­tion con­trol warn­ing lights, a bad wheel bear­ing can cause an ir­reg­u­lar wheel speed sig­nal. This will cause the warn­ing lights to come on but not nec­es­sar­ily set a code. If you are us­ing an OBD2 code reader, most only read emis­sions codes, not ABS codes. You need a scan tool that will read ABS sys­tems to see if there are any codes in that sys­tem. When you fix the wheel-bear­ing prob­lem, the wheel speed sig­nal prob­lem should be cor­rected, too, and the warn­ing lights will go out the next drive cy­cle.

Newspapers in English

Newspapers from Canada

© PressReader. All rights reserved.