Maximizing Tools: Unconventional Diagnostic Methods, Part II
In this second installment, Riverland Technical and Community College Instructors Olle Gladso, Vladimir Postolovskyi and Andrew Bezhanov provide more unconventional diagnostic procedures to try with your digital mulitmeter.
Pulling Codes: A Mercedes-Benz Story – A P0300 Analysis Using Exhaust Waveforms
This article will document the P0300 code for a 1996 Mercedes-Benz. A single cylinder misfire has occurred, and the technician decides to clear the code in my presence. I advised that it is a good strategy to maintain the code information for review. It’s clear that misfire activity can be challenging on some ignition systems, and I’ve found through my research that all of the car manufacturers appear to run their monitors in a similar fashion, but it’s still wise to review their service information for the differences and details of their systems.
Tech Tip: Volkswagen Check Engine Light Is On With Trouble Code P2187
The check engine light is on, with trouble code P2187, too lean off idle bank 1. This “Fast Fix” from Identifix shows how one tech solved this issue.
PCM Diagnostics Case Study: No-Code Misfire Diagnosis On A 1998 Toyota 4Runner
When doing mobile diagnostic work for other shops, contributing writer Gary Goms usually sees more than his share of random no-code engine performance complaints. In the following case study, the customer of a client shop complained about an intermittent rough idle on his well-maintained 1998 Toyota 4Runner, but only when it was driven in hot weather. The client shop couldn’t duplicate the complaint, no matter how long the engine ran. Of course, the lack of DTCs didn’t help the diagnostic process.
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.