EFI Diagnosis
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EFI Diagnosis. Step 1 – Listen to the Customers Complaint. The customers complaint will point you in the general direction in your diagnosis Don’t allow the customer to steer you in the wrong direction
EFI Diagnosis
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Presentation Transcript
Step 1 – Listen to the Customers Complaint • The customers complaint will point you in the general direction in your diagnosis • Don’t allow the customer to steer you in the wrong direction • Get used to the customer’s language (Does it sound like a rod knocking, or sound like when the kids put wooden blocks in the cloths dryer?) • Don’t tell the customer that their “diagnosis” is wrong (at least not directly) • Ask relevant questions (Engine temperature, Speed, Frequency) • Don’t jump to conclusions
Step 2 – Verify the Complaint • Test drive the vehicle and verify the complaint • Helps you more clearly understand the customer’s complaint • You will then know what to look for after making the repair, to verify that the symptoms are gone • Make note of relevant conditions (engine load, RPM, throttle position, engine temp, transmission gear)
If You Can’t Duplicate the Complaint • Have the customer drive the car • It may be that the customers driving style is contributing to the complaint • Ask the customer for more details about the complaint • Check TSB’s (Technical Service Bulletins) • Check the ECM for any stored fault codes
Once You Have Verified the Complaint • Systematically narrow your diagnosis down • Troubleshooting chart • Use service information • Sensor range specifications • Wiring diagrams • Description of operation
Once You Have Found the Problem • Talk to the customer and explain to them, in as non-technical terms as possible, what you have found. Address the following questions before the customer asks: • What is the problem? • What caused the problem? • What should be done to repair the problem? • What will it affect if the problem isn’t repaired?
Once the Problem Has Been Repaired • Test drive the vehicle to verify that the repair has indeed fixed the problem • There may be additional problems • When test driving, notice any other problems with the vehicle, even if they aren’t related to the original problem the customer came in for • Let the customer know about any problems you noticed when test driving and let them know how important it is to have them repaired • What is the problem? • What caused the problem? • What should be done to repair the problem? • What will it affect if the problem isn’t repaired? • Clear any trouble codes stored in the ECM
Diagnosis Equipment • Your Brain • Service Manual • Scan Tool • DVOM • Lab Scope • Fuel Pressure Gauge • 4 or 5 Gas Analyzer • Compression Tester • Leakdown Tester
Scan Tool Diagnosis • A scan tool is a useful piece of diagnostic equipment and will allow us to “see what the computer is seeing” • A scan tool is not magic and will not fix the vehicle by itself • Scan tool will provide us with various information • Trouble Codes • Data Stream • Service Programming (OBDII with a Tech II or equivalent)
Trouble Codes • Trouble codes will be set if the ECM sees sensor data outside a specific range • Look at the service information for specifics • You must determine why that sensor was out of range • Faulty sensor • Sensor was monitoring improper engine operation • I.E. O2 Lean Code • Faulty O2? • Clogged Fuel Filter?
Data Stream • Using a scan tool to monitor the data stream, essentially allows you to see what the ECM is seeing, in terms of the various sensor signals • By referencing the service information, we can determine if the value the ECM is seeing is correct