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Advanced Emission Diagnostic Training

Advanced Emission Diagnostic Training. Why baseline Before and after repairs Baselining with a 5 gas analyzer Baselining with a scope, scan tool, or DVOM Correlation of baseline reading with Bar ‘97 test results. Advanced Emission Diagnostic Training.

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Advanced Emission Diagnostic Training

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  1. Advanced Emission Diagnostic Training • Why baseline • Before and after repairs • Baselining with a 5 gas analyzer • Baselining with a scope, scan tool, or DVOM • Correlation of baseline reading with Bar ‘97 test results

  2. Advanced Emission Diagnostic Training • Diagnosing an emission failure is different from many auto repairs • Sometimes a vehicle will “run fine” but fail a smog test • It can be hard for a tech or customer to visualize a smog failure

  3. Advanced Emission Diagnostic Training • A baseline test consists of: • Monitoring all 5 gases at: • Stabilized operating temperature • Idle • 3000 RPM (no load) • ASM mode 1 • ASM mode 2

  4. Advanced Emission Diagnostic Training • Performing a baseline test before and after a repair will be an indication of how successful your repair was • Sometimes a repair of one gas will raise another gas out of limits • Remember you are going to compare the two sets of readings, so always perform a before and after baseline test exactly the same, or results will be inaccurate

  5. Advanced Emission Diagnostic Training • Analyze the “after repair” baseline readings and the “before repair” baseline readings by comparing the two sets of readings. • Calculate the difference in percentages • If the percentage of reduction is the same or higher (cleaner) • Your repair was probably successful • Be sure to check the other gas readings

  6. Advanced Emission Diagnostic Training Equipment used to gather baseline readings • DVOM • Hook up to 02 sensor • Positive lead to 02 sensor return wire • Negative lead to good ground • Scan tool • Hook up and program

  7. Advanced Emission Diagnostic Training • DVOM to fuel injector (if no data stream) • Positive lead to fuel injector ground • Negative lead to good ground • Set on ms scale • Warm up vehicle • Monitor the O2 ( voltage & frequency) and the Injector (pulse width) simultaneously. • O2 should fluctuate above and below .450 volts at least once every couple of seconds • A rich exhaust must = a lean command

  8. Advanced Emission Diagnostic Training • If 02 sensor reading is biased high or low you have a problem (may not be 02 sensor) • Baselining using the 02 sensor and M/C command will monitor CO only

  9. Advanced Emission Diagnostic Training • A digital storage oscilloscope (DSO) will give more accurate information • If a small misfire is present more oxygen is in the exhaust stream • The 02 sensor wave form will have a higher frequency • Using this method only CO & HC problems can be identified

  10. Advanced Emission Diagnostic Training • BAR ‘97 analyzer • Road test -- put on analyzer • Monitor and record all 5 gases during 4 conditions mentioned before • Other test equipment utilized during this baseline test may include timing light, DSO, Digital Pyrometer etc.

  11. Advanced Emission Diagnostic Training • Special note: If all OEM emissions equipment is not hooked up and operating as designed, baseline test results will be inaccurate. (missing, modified or disconnected emission systems must be repaired first!)

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