Maximizing Tools: Unconventional Diagnostic Methods, Part I
Explore some unconventional uses of a digital multimeter that will allow you to diagnose problems without a significant investment of time and effort.
Using Fuel System Testers To Diagnose Driveability Concerns
Shop owner and automotive trainer Karl Schneider helps you fix driveability concerns, focusing on loss-of-power issues on vehicles with an electric return fuel system.
Diagnostic Solutions: Variable Camshaft Timing And Back Pressure Issues
When the topic of variable valve timing (VVT) comes up in import repair shops, few realize that the concept of increasing low- and high-speed engine torque by automatically advancing and retarding valve timing isn’t a recent development. For example, I recently discovered an old variable camshaft timing gear that I bought during the 1960s featuring a torsion spring device that retards valve timing in response to the increased rotating torque needed to turn the camshaft at higher engine speeds.
Volkswagen Feature: Don’t Miss Out On Missed Maintenance
“We don’t work on those V8s.” I’ve often heard that said in reference to the 4.2L VW and Audi 8 cylinders. Some criticisms are that the timing belts require too many special tools and you can’t see the engine. I hear a lot of excuses when it comes to V8 Audis and VWs, but, in reality, they are not much different than the V6s and most models don’t require too many special tools. There are many shops that don’t want to do a timing belt replacement on the 4.2 V8, but it’s time to buy the tools and stop sending good paying jobs to competitors.
Diagnosing Exhaust Gas Recirculation (EGR)
Exhaust gas recirculation is the dilution of the air/fuel mixture to control amounts of exhaust gas. Since exhaust gas does not burn, this lowers the combustion temperatures and reduces NOx emissions from the engine. At lower combustion temperatures, very little of the nitrogen in the air combines with oxygen to form NOx. Most of the nitrogen is simply carried out with the exhaust gases.
Diagnostic Dilemmas: Building A Plan For Diagnosing Electrical Problems
Every once in a while, I see the topic of a diagnostic check sheet come up on the International Automotive Technician’s Network (iATN) or other industry media. Most often, the question is asked by a shop owner or service writer who is trying to simplify his life by devising a “canned” step-by-step approach to solving various electronic diagnostic problems. Although a canned procedure is a good place to start, it’s not a sure-fire way to solving electronic problems.
Tech Tip: Chrysler’s Engine Experiences No Crank/No Start Condition Due To Electronic Lockup Of WCM/SKREEM
The customer will experience a no engine crank and a no engine start condition. Also, the remote keyless entry (RKE) system will not operate. This condition may be due to an electrostatic discharge (ESD) from the ignition key into the WCM, causing the WCM to electronically lockup. This condition may occur more frequently in dry and/or cold weather conditions where a sufficient electrostatic charge is more easily produced. This condition is corrected by the replacement of the WCM.
Tech Tip: White Smoke Blowing From Tailpipe?
A classic sign of a head gasket problem is when the vehicle is blowing white smoke from the tailpipe. This indicates that water/coolant is entering the combustion chamber and is then burnt off as steam through the exhaust. The white “smoke” is water vapor as the steam condenses when it hits the colder atmosphere.
Tech Tip: Ford/Mercury’s Engine Stalling On Engagement/Stopping
Some 2005-’08 Ford Escape and Mercury Mariner vehicles equipped with a CD4E automatic transaxle and built from Aug. 1, 2004 through Feb. 15, 2007, may exhibit an engine stall when coming to a stop or when engaging the transmission into drive or reverse.
Tech Tip: Subaru’s A/T Temp Light Flashing, But No DTCs Stored, Erratic Shifting Complaint
If you encounter a late-model D4AT-equipped vehicle with an erratic shifting complaint, and possibly a DTC P0712 in memory, there may be a poor connection in the transmission wiring harness. There have been cases of open circuits or high resistance isolated to the white plastic pass-through section of the transmission harness or the harness itself. It’s important to note that the P0712 may not be set when the condition occurs.
Tech Tip: Honda Squeaks Or Rattles In Rear Damper Area
There’s a squeak or rattle coming from the rear of the vehicle when it’s driven. On Japan-built CR-Vs, the rear damper assembly includes a small metal hook and body bracket, which are used only during vehicle assembly at the factory. The hook or the bracket may have been bent and is touching the vehicle body or the damper assembly, causing a squeak or rattle.
Gonzo’s Toolbox: Who’s The Boss? Deal With The Person In Charge, Especially When Your Customer’s Vehicle Is A ‘Basket Case’
There’s a boss in every family, and sometimes you might think it’s you, but your spouse may have a different opinion. For example, there have been countless times I’ve had a car in the shop where a wife or husband has dropped the car off and the repair is done, paid for, and sent on its way, only to have the other spouse call and give me an earful because they weren’t told what had transpired. (As if that’s my fault!)