Auto Service World
Feature   May 1, 2006   by Tom Venetis, Editor

Make emissions systems a part of regular maintenance

Customers might not know what an emissions system is, but a savvy technician can spot problems before they become a major repair bill.

Automobile owners rarely think about the emissions system. The only time is when the little red ‘Check Engine’ light suddenly goes on, or after having received a notice in the mail from the government that the vehicle must pass an emissions check so it can be certified.

Domenic Ninni, with ACDelco’s technical and product support and training group in Oshawa, Ont. said emissions systems today have become so sophisticated, it has become difficult for shop technicians to sell emission maintenance to automobile owners. In fact, because today’s emissions systems are so well designed and integrated into modern engines, there often is no set maintenance schedule for a technician to follow.

Because of this lack of fixed maintenance schedules, Ninni recommends technicians make inspecting the various parts of an emissions system a regular part of normal inspection schedules on a vehicle. Simply, when a customer comes in for a regular tune-up, a technician should use that time to check the emissions system and its various parts. He recommends technicians first focus attention on those parts that are wear-out items, such as air filters, valves, belts, hoses and air pumps. But most especially, such critical wear-out components as spark plugs and oxygen sensors, which if either fails or suffers from some wear or damage, will affect the efficient operation of an emissions system and automobile engine.

One spark away from savings or problems

It used to be that technicians had to replace spark plugs rather often, especially when spark plugs were nickel-based. But with the introduction of platinum-based spark plugs, the operating life of the spark plug was extended, with some manufacturers suggesting the spark plugs be replaced after 100,000 km or more.

Jay Buckley, technical training manager with the Honeywell Consumer Products Group in Troy, Mich. said he ‘cringes’ when he hears about replacing spark plugs at the intervals some manufactures place on the spark plug box. He strongly believes technicians must inspect and replace spark plugs, even the platinum-based ones, much more frequently than is recommended. The reason is that over time metal corrosion could set in and the spark plug becomes fused to the cylinder head and near impossible to remove safely. Buckley recommends vehicles that use the older nickel-based spark plugs have them replaced every 30,000 miles (48,000 km), platinum-based should be replaced every 60,000 miles (96,000 km).

“I have a shop and I always ask clients if I can inspect the plugs during a regular maintenance check because I want to make sure those plugs come out of the cylinder head,” Buckley added. “It becomes very ugly when you remove a plug at 120,000 miles and the threads come out of the head. Then it becomes a very expensive repair instead of a simple tune-up for the customer.”

Ninni recommends technicians routinely take one or two sparks plugs out during a regular maintenance check of a vehicle and visually inspect the plugs. It does not take a lot of time, but regular visual inspections of the spark plugs will not only keep the plugs and the emissions system running smoothly, a visual inspection can also offer a hint of other, less obvious problems that may be happening in the engine and emissions system.

For example, if the technician pulls the plugs and notices deposits it likely means the fuel injectors are getting dirty and it is a good idea to run a fuel injector cleaner through the engine. An added benefit is regular cleaning of the injectors will improve emissions performance along with overall engine system performance.

Physical damage to the spark plug can mean there is some kind of damage inside the engine or emissions system. If the side wire of the plug is bent or folded over, chances are something may have been ingested through the engine. Buckley said he once noticed such damage to a plug on a client’s car and upon further inspection he found a piece of the car’s piston had broken off and bounced around in the chamber.

Melting on the side wire or the centre wire might be an indication that the engine had episodes of pre-ignition caused by a clogged fuel injector and the engine running lean.

“A good technician, by looking at a spark plug, can almost determine the physical condition of the engine and the fuel and emissions system,” Buckley said. “If everything is working fine, then the plug can only look one way: everything is clean, the insulator is white and there is little if any deposit on the plug. If there is a dry black deposit on the plug that is usually caused by a dirty air filter; if the deposit is black and wet that is oil fouling and that could mean the piston rings or valve guides are worn. All of those problems will cause you to have poor emissions.”

Doug Morrison, technical service manager with NGK Sparks Plugs Canada Ltd. in Calgary, Alta. said often neglected aspects of emissions system maintenance when it comes to the spark plugs are the wires. Replacing plugs is one thing, but if the wires are fouled or damaged due to age or mechanical defects, new spark plugs are simply not going to make that much of a difference in how the emissions system or engine will run in the long run.

Morrison believes technicians should replace the wires every 100,000 km or after five years of use. He said technicians must be up-front with clients about the need to replace the wires. If the client argues against the replacement, thinking the technician is just looking to make an extra bit of money from a supposedly necessary replacement of a part, Morrison said the technician should then say they cannot guarantee the tune-up or the emissions system running properly.

“As soon as you tell a customer that you cannot guarantee the tune-up, and that customer is paying for $400 on labour, they will say, ‘Sure, go ahead and replace the wires,'” Morrison added.

Too much or too little oxygen

Oxygen sensors are another critical component of an emissions system that often gets overlooked during regular maintenance checks. That is until something goes wrong and a customer comes in complaining of losing fuel economy, engine performance and emissions efficiency.

Bill Marchetti, district service manager with Robert Bosch Corp. in Broadview, Ill. said with the advent of OBD-2, technicians should make regular use of the diagnostic information now provided to check the oxygen sensors for its response time, making sure it can go from its ‘lean’ setting to ‘rich’ in 100 milliseconds. As well, today’s newest oxygen sensors are equipped to be ‘wide-band’ and can now tell a technician how ‘rich’ or ‘lean’ the oxygen/fuel mixture is. All this information can be used to make sure the oxygen sensor is running correctly and an emissions system is operating efficiently, and prevent such annoying things as misfiring or the engine running rich and thereby causing too much fuel to be used and excess emissions. Either condition can also affect the life of the catalytic converter, an expensive repair job for a client if it is damaged.

“With the new generation of oxygen sensors, (Bosch’s) stance is that if there is a symptom that leads to a technician having to do a test then change the sensor,” Marchetti added. “Many of today’s sensors have a ‘check’ time and Bosch recommends following those suggestions.”

He added that if an oxygen sensor fails on an OBD-2 vehicle, that vehicle will likely run fine and even get the vehicle’s stated fuel economy. But the technician and customer will likely notice a decrease in engine performance.

Ninni recommends technicians replace oxygen sensor routinely at 100,000 km as part of any regular maintenance schedule.

Morrison said another issue that sometimes can affect an oxygen sensor is fuel with ethanol as part of the mix. Ethanol in fuel is becoming more common now, usually averaging between five to 10 per cent ethanol in the fuel mix. Ethanol is supposed to run cleaner and make the engine run more efficiently. However, Morrison has encountered a few instances where the ethanol has caused oxygen sensors to run ‘lean.’ This triggered the sensor to compensate by running more fuel through the engine, actually burning more fuel during normal operations than what the engine normally would.

“So what we recommend is putting ‘colder’ heat ratings in and close the cap settings up by .010,” Morrison said. “If you have a .010 gap reduction you will get a stronger spark, compared to a wider flame front that will burn up all the fuel in the chamber. Now the sensor can do its job properly.”

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