Tips and Tricks

1
Tips and Tricks

• NACAT 2001
• Winnipeg, Manitoba, Canada
• July, 2001
• James D. Halderman
• Sinclair Community College
• Dayton, Ohio
• jdhalderman_at_aol.com

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5-Gas Exhaust Analysis

• Five-gas analysis is sometimes difficult for
  students to understand.
• Tip
• Your Nose Knows
• If you smell exhaust, it is unburned fuel (HC).

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5-Gas Exhaust Analysis

• If your eyes water, it is oxides of nitrogen (NOx
  plus water around your eyes forms a mild nitric
  acid solution which burns your eyes).

4
5-Gas Exhaust Analysis

• If you get a headache or feel dizzy, it is likely
  caused by excessive CO emissions.
• Think of CO meaning clogged oxygen or not
  having enough air for the fuel or having too much
  fuel for the available oxygen.

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Easy to Remember Specifications

• w/o CAT w/ CAT
• HC 300 ppm or less 30 - 50 ppm or less
• CO 3 or less 0.3 - 0.5 or less
• O2 0 - 2 0 - 2
• CO2 12 - 17 12 - 17
• NOX less than 100 ppm _at_ idle
• less than 1,000 ppm _at_ WOT

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Quick and Easy Tip

• CO should equal O2
• CO rich indicator
• O2 lean indicator
• If both are the same, the mixture
• is OK

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5-Gas Sample Question 1

• What is wrong?
• HC and CO2 high and
• CO and O2 low

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Answer to Question 1

• The problem is most likely ignition (spark
  stuff) related.
• It is OK for CO and O2 to be low.
• It is OK for CO2 to be high (high efficiency)

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5-Gas Sample Question 2

• What is wrong?
• HC 3 ppm
• O2 20.8
• CO 0
• CO2 0
• NOX 3 ppm

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Answer to Question 2

• The exhaust probe was not in the tailpipe!
• No carbons (CO and CO2) indicate no combustion
  occurred.
• Tip
• Think of CO and CO2 as ash left over from a fire.
  No carbon no fire!

11
Fuel Injection Tip

• Use a stethoscope on an injector.
• Should hear a clicking sound not a clunking
  sound
• Students really understand fuel injectors if they
  hear them work.

12
Quick and Easy Trick

• Use a stethoscope to listen at the fuel return
  line from the fuel pressure regulator.

13
Quick and Easy Trick

• If you hear fuel moving back to the tank, the
  fuel pump pressure is greater than regulator
  pressure.
• If you do not hear fuel moving, the fuel pump or
  the fuel pressure regulator could be defective.

14
Sensors

• High Authority sensors include
• 02S when in closed loop
• MAF
• MAP
• ECT especially at engine start
• TP

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Sensors

• Low Authority sensors include
• IAT
• BARO (if separate from MAP)
• TFT

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Sensor Tip

• If in doubt
• take it out.

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Tip Explanation

• A high authority sensor can be skewed,
• Which means that it is working OK but not
• accurately measuring the engine condition.
• If the engine runs better with a sensor
  disconnected, the sensor is either defective or
  is somehow measuring the condition incorrectly.
• If disconnected, PCM substitutes a replacement
  value.

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Student Projects

• Lighter Socket to Meter
• Heated Oxygen Sensor to Meter
• Extension Cord and Plug to Check Relays
• Fused Meter Lead
• Fused Jumper Wire
• Wheel Speed Sensor to Double Banana Plug

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Lighter Socket to MeterFused Lighter Plug
274-335/Double Banana Plug 274-717
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Heated Oxygen Sensor to Meter
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Extension Cord and Plug to Check Relays
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Fused Meter LeadInline Fuse Holder 270-1213
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Fused Jumper Wire
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Wheel Speed Sensor to Double Banana Plug
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Neat Websites

• www.autoclassroom.com (free)
• Free membership
• Includes useful worksheets, handouts, and
  PowerPoint presentations
• Please send your stuff to the webmaster so the
  site can grow

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Neat Websites

• www.aeswave.com
• New scan tool for
• Palm Pilots for
• generic OBD II
• Books, tools,
• equipment, meter
• leads, etc.

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Neat Websites

• www.iatn.net (free)
• Over 30,000 technicians online
• Fee to join
• Become a sponsor (10 per month), which gives
  access to the data base

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Neat Websites

• www.transonline.com (free)
• Automatic transmission site
• Valve body photos
• Check-ball locations

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Neat Websites

• www.asetestprep.com (pay site)
• 29.95 for 30 days
• All eight ASE areas plus L1
• Guaranteed to pass the ASE test or your money
  back
• Can be used for distance learning and/or a credit
  course at your college