ASP's 10th Annual ‘Tips from Techs’ Feature!
Tidbits of Wisdom Shared Among Readers
In our 10th installment of Techs Helping Techs, we have the opportunity to allow our readers to share valuable information, for the benefit of all. We all run into diagnostic and repair instances wherein we discover a few tricks. Instead of keeping that valuable information to ourselves, sharing the tips and tricks helps everyone in the service industry to do a better job. Our thanks to those who submitted their experiences.
Being prepared for an emergency is something many customers ignore. For example, those who drive in winter weather, especially in a remote area, a basic safety kit is a great idea in the event that they become stranded.
The kit can include a flashlight (with extra batteries), a battery-operated strobe light or flare, a compact thermal blanket that folds up into a few-inches-square and is designed to contain body heat, a water bottle, a small packet of dried/preserved snacks, a folding pocket knife (good for cutting a stuck seat belt), a spring-loaded glass breaker tool, a pair of gloves, a first aid kit and a cell phone 12v charger.
These are merely examples. An emergency kit can easily be expanded to include items such as a fold-up shovel, a small fire extinguisher, hand sanitizer, a small multi-tool kit, a strong cordless impact wrench and socket to fit the wheel nuts, duct tape, etc.
All of these items can be packed in a small zippered duffle bag or plastic box.
It’s better to have these items and not need them than to need them and not have them. A kit like this can come in handy if they run out of gas or otherwise break down in a remote area or if they run out of gas while waiting in a hours-long traffic jam, or in the case of an accident where there are no responders nearby.
Many people don’t think of this until faced with an emergency, when it’s too late. Something to mention to those who may be at risk, especially for those travelling in cold climates. We actually assemble kits like this and offer them for sale. In many cases, customers are more than willing to purchase them, usually saying that they never thought of that before.
Baker & Sons Auto
SUPER DUTY FUEL PRESSURE
If you have a 6.7L Ford Super Duty diesel with the MIL on and you find code P0087 and/or P2291, you have a fuel pressure issue.
Before you get carried away and assume that the high pressure fuel pump has a problem, check the low pressure fuel circuit first. You may simply have a clogged/dirty fuel filter.
Connect a gauge to the low pressure system and crank the engine. If pressure is below specification, remove the filter and drain the fuel bowl. Make sure the bowl is clean and install a new filter.
If you find an engine rattle noise in a Honda V6 equipped with VCM (variable cylinder management), and the MIL blinks and the engine runs rough, you probably have a case where the VCM rocker arms are sticking under steady cruise or during light acceleration.
Vehicles include 2013-2016 Accord, 2010-2015 Crosstour, 2011-2016 Odyssey and 2009-2015 Pilot vehicles as examples.
When the VCM rocker arm pin taps against the next rocker arm, it tries to lock the two arms together, going into valve pause. The headache you can face is that this can be intermittent. If the rocker arms un-stick, you’ll have no misfires and no DTCs will set.
Check the Variable Cylinder Management Rocker Arm test in the service manual to check to see if the rockers are working correctly. If any of the rockers are sticking, simply replace the affected arms.
LOOK FOR SIMPLE FIRST
We’ve had more than one customer come in to complain about rear power windows not working. They tell us that they’ve looked in the owner’s manual to find the fuse location, only to find the fuses OK.
“Yesterday the windows worked but now they won’t go up or down.” You can tell that they’re afraid that they need a new window regulator, or that the power window motor or wires are fried, etc., fearing a big repair cost.
Many four-door vehicles have a rear window control panel in the rear, maybe at the rear base of the center console. Check that first. It’s very possible that they’ve tossed something back there that rested on the switch that locks the windows out.
The last one we saw had a large flashlight laying directly on the switch. We simply removed the flashlight, verified window operation and sent them on their way at no cost. They may be embarrassed, but chances are they’ll never make that mistake again, and they appreciate our honesty.
A/C BLOWER ISSUE
Here’s a case where a previously installed part went bad, before the vehicle came to us.
A customer with a 2013 Ford Edge said that the A/C blower had intermittent operation. When he ran the air conditioner, the blower motor would run for a while and then stop, and then start again.
We checked HVAC operation and confirmed that the blower would stop intermittently and then start again. The A/C pressure switch had been replaced. The wiring harness to the HVAC connector was replaced due to loose terminals. No codes were found in any modules.
The next day, DTC B10b9 showed up (blower control circuit short to ground or open). By talking to the customer, we found that the blower relay had recently been replaced. The relay was hot to the touch.
We installed a jumper wire and amp meter and found that the blower was drawing 20 amps. With the relay jumped, the blower tripped my 30 amp circuit breaker.
High amp draw of the blower was causing the issues. We replaced the blower and had a draw of 13 amps. We replaced the relay as well, as it was found to be defective. The system operates now as designed.
Mitchell1 Community member
2005-2007 Ford F-350 Super Duty trucks were available with a 6.0L Power Stroke turbo diesel engine. The turbocharger is a VGT type (variable geometry turbo) that features vanes designed to increase or decrease turbo volume as required by demand.
However, this style of turbo is easily clogged with soot and can stick in the open position. This has a detrimental effect on throttle response as it takes more time to spool up.
Removing the turbo, performing a disassembly and cleaning is the normal fix. However, it may be easier to run the engine at wide open throttle for a short period of time in an effort to blow out the soot.
The 2005 and 2007 models also had a drain tube that was too small, which can result in oil cooking inside the turbo.
It’s important to note that if the turbo is completely disassembled, the compressor/turbine shaft assembly should be re-balanced, as loosening and tightening the shaft nuts can alter the state of balance.
An out-of-balance turbo can destroy itself in short order. This holds for any turbocharger, regardless of the vehicle make/model.
The HD Shop
If you’re dealing with a BMW equipped with the N20 or N26 2.0L turbocharged engine (an example is the 2016 3, 4 or 5 Series), when starting a cold engine, you might see blue smoke exiting the tailpipe for 20-30 seconds. You may not find any turbo fault codes and there may be no drivability issues.
If this is the case, it’s likely that when the vehicle is parked overnight, residual engine oil pressure tends to equalize, forcing oil to migrate past the turbocharger exhaust-side turbine seal.
If this is what you’re faced with, the fix is pretty simple. Replace the engine oil feed line to the turbo using P/N 11 42 8 648 368, which is a new oil supply line that now features a check valve on the engine side of the engine oil feed line. This will eliminate the engine oil getting into the turbo exhaust side seal as oil pressure starts to equalize, finding a path to the turbo exhaust side.
The German HQ
SHORT TRIPS WITH GDI
Excess fuel diluting engine oil obviously is not a good thing. This can happen with either traditional port injection spray fuel into the intake runner or with gasoline direct injection (GDI) where fuel is sprayed directly into the combustion chamber.
While dripping (faulty) injectors in a port system can lead to oil dilution, this can be more extreme with a GDI system, where excess fuel runs past the rings and into the oil sump, especially if the vehicle is driven for very short trips on a regular basis, where the engine never has a chance to warm up to normal operating temperature.
In the case of a Mazda with GDI, for example, excess fuel in the oil can result in the check engine light on, with DTC P0172:00 (air fuel ratio too rich). This is due to a larger than normal amount of fuel evaporating and burning off in the combustion chamber, where the amount of fuel coming from the PCV system increases and exceeds the air fuel correction ratio correction system limit. Excess fuel entering the crankcase obviously causes the oil level to rise in the sump.
Caution your customers who drive only very short distances on a regular basis. If the check engine light comes on regularly and the oil level on the dipstick is above normal, the engine oil and filter must be changed.
In other words, a routine of short trips means that the engine oil change interval needs to be reduced (change oil and filter more frequently).
High Street Service
Left: Excess fuel mixing with oil, diluting the oil and rising oil level. Right: Small amounts of fuel entering the crankcase may have time to evaporate without increasing oil level. Courtesy of Mitchell 1
PORSCHE FUEL PRESSURE CODE
A fault code P0087 (fuel rail/system pressure too low) may be stored in the engine control module when the fuel pressure is not as expected. A number of issues may cause this fault code to be set such as a faulty fuel rail pressure sensor, a mechanical fault with the inlet metering valve or rail pressure control solenoid could cause the valve to become stuck.
An electrical fault such as an open circuit in the inlet metering valve or fuel pressure control solenoid on a system with a normally closed valve will also cause this.
A short circuit on the control wire of a normally open inlet metering valve will also cause this fault. A fault in the fuel injector return system may cause the fuel pressure to be low. This causes fuel from the high pressure circuit to leak back into the low pressure circuit. A faulty maximum pressure relief valve can also cause this fault.
The high pressure fuel pump should be tested to make sure that it’s capable of delivering the required fuel volume.
German Planet Auto
IT WASN’T THE SENSOR
We recently worked on a 2007 Buick Terraza CX 3.9. The customer noted that the ABS light was on.
We scanned and found code C0040 (right front wheel speed sensor circuit malfunction). With the scan tool connected, we cleared the code and performed a road test. As we monitored the ABS wheel speed sensors, we found the signal parameter from the right front ABS sensor was not present.
We raised the car on a lift and inspected the right front speed sensor connector, terminals and wiring and found no faults. With the key on, we back-probed the right front sensor signal wire with a lab scope. As the wheel rpm increased, frequency (Hz) should also increase with no drop-outs or other glitches. The speed sensor did not produce an observable signal or waveform when monitored on the lab scope.
With the key on, and the right front wheel speed sensor disconnected, we used a multi-meter to measure the 12 volt supply and less than 100 mV ground at the connector, and found that the 12 volt supply was not present.
With the key on, we back-probed the anti-lock/traction control module with the multi-meter to measure the specified 12 volt supply at terminal “9” for the right front speed sensor, and found that the 12 volt supply was not present. We then back-probed the module’s terminal “46” for the 12 volt supply and terminal “1” ground, and found both were present.
The results of the test verified that the anti-lock/traction control module was faulty. We replaced the anti-lock/traction control module, cleared codes, road tested and the ABS light did not illuminate and the vehicle operated properly. Instead of initially assuming that the right front wheel speed sensor was at fault, detailed testing discovered the bad module.
Mitchell1 Member contributor
Just because the DTC C0040 indicates a malfunction of the right front wheel speed sensor circuit, don’t automatically assume the sensor itself is the problem.
Many car owners today are obsessed with attaining optimum fuel mileage, and that’s understandable, given the cost of fuel. However, some take things beyond safe limits by intentionally over-inflating their tires.
The theory is that by increasing tire inflation, you reduce rolling resistance, which obviously should improve fuel mileage. However, there are too many downsides to this. By increasing tire pressure from, say the recommended 40 psi, to 60, 80 or even 100 psi as examples, you’re doing more harm than good.
First of all, the ride will be more harsh, as tire sidewall compliance is reduced, reducing or eliminating the “cushion” that the tires should provide. This reduction of cushion/shock absorption allows vibration and impact forces to be transmitted to the suspension and steering components, increasing parts wear.
Next, by over-inflating, you change the tire’s contact patch from a relatively even tire tread-to-road contact to the tire contacting the rod surface only at the tread center. This results in premature tire wear (at the center tread area), and by reducing the contact patch, the vehicle’s handling during highway speed, turns and braking is degraded, resulting in a potential loss of vehicle control. On wet or slippery roads, this makes matters even worse.
Over-inflation seems to be more common with owners of hybrid vehicles, where the owner’s primary goal is to reduce fuel use. The trade-off is simply not worth the potential couple-of-miles-per gallon improvement.
Also, all tire sidewalls feature construction information, including “MAX” tire pressure. Tires that are designed to carry, say, 35 – 40 psi may have a MAX inflation pressure rating of 50 psi. This MAX rating is NOT the suggested inflation pressure. Rather, it’s the maximum allowable inflation pressure for the specific tire and vehicle.
Regardless of good intentions, drivers need to be made aware that they should only inflate the tires to the recommended pressure listed on the door jamb label (and in the owner’s manual). The well-intended severe over-inflation is similar to some folks’ assumption that by adding eight quarts of engine oil into a sump designed for five quarts is a clever idea so that the engine (which may be leaking oil) will not run out of oil. Overfilling an engine’s oil capacity will severely damage the engine as the crankshaft whips the oil into a foam, and severe over-inflating the tires will promote early tread wear and create unsafe handling.
Just don’t do it.
Examples of inflation as it relates to the tire’s tread contact patch. Far left: Correct inflation maximizes the tread contact patch to the road. The majority of the tread contacts the road when driving straight, providing tread shoulders to contact during turns. Center: Under-inflation places more load at the outer and inner tread areas, minimizing center tread contact. This creates early tread wear at the outer/inner tread areas and provides a spongy ride and sloppy handling. Far right: Over-inflation balloons the tire so that only the center tread area makes contact, resulting in early center tread wear, a harsh ride and a severe reduction of road grip. Courtesy of Uniroyal