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Handling No Trouble Code Problems


Your car has a problem. So, naturally, the first thing you do is check for Diagnostic Trouble Codes to see what the problem is. But there are no codes. So now what do you do?

You are driving to work one morning and the sun is shining, the birds are singing and the daily driver is purring along like a kitten. You stop at a traffic light and when you turns green you start to go, but when you hit the gas it bucks and stalls.

You then utter a few choice words from that special vocabulary you never use when Mom is in the room. You start it back up and nurse it along until you get to work and, of course, your boss just nods his head when you tell him you were late due to car trouble. On the way home it stalls only once and is otherwise running just fine.

So you know that Saturday is the day you will track this problem down and fix it. You access the computer to see what the codes are and you are stumped when there are no codes stored. So you scratch your head and wonder what to do now.

Intermittent problems like this can be very difficult to locate, and you usually have to wait until the problem becomes more consistent before there is a reasonable chance of locating it.

Symptom checks cannot be used properly unless the drivability problem characteristic actually happens while the vehicle is being tested. Otherwise everything will check out good and you won't find the problem.

Select the symptom that most accurately describes the vehicle's drivability problem and then perform the test routine that pertains to this symptom. Perform each routine test in sequence until problem is found. For definitions see Glossary Of Terms.

You should note that these are the most likely causes of a particular problem, but not necessarily the cause of the problem you are experiencing. Some of the possible causes listed may not even apply to your vehicle.

Remember that these are general instructions. For more detailed instructions, procedures and specifications pertaining to your specific vehicle, consult an appropriate repair manual.

SYMPTOMDIAGNOSTIC TEST
Hard StartCheck Secondary Ignition System
Check Engine Vacuum
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAT Sensor
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check Engine Mechanical Systems
Check EVAP Emission System
Check EGR System
Start And StallCheck Secondary Ignition System
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check PCM Power And Ground Circuits
Hesitation
Sag
Stumble
Check Secondary Ignition System
Check Engine Vacuum
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAT Sensor
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EVAP Emission System
Check EGR System
Check For Oxygen Sensor Switching
Check O2 Sensor Heater
Check PNP Switch
Check PCM Power And Ground Circuits
SurgeCheck Secondary Ignition System
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EVAP Emission System
Check For Oxygen Sensor Switching
Check PCM Power And Ground Circuits
Lack Of Power
Sluggish
Check Secondary Ignition System
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EGR System
Check For Oxygen Sensor Switching
Check PCM Power And Ground Circuits
Spark Knock
Detonation
Check Secondary Ignition System
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EVAP Emission System
Check For Oxygen Sensor Switching
Check PCM Power And Ground Circuits
Cuts Out
Misses
Check Secondary Ignition System
Check Fuel Pressure
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EGR System
Check For Oxygen Sensor Switching
Check PCM Power And Ground Circuits
Backfire
Popback
Check Secondary Ignition System
Check Fuel Pressure
Check MAP Sensor Calibration
Check The Minimum Idle Air Flow
Check EGR System
Check For Oxygen Sensor Switching
Check PCM Power And Ground Circuits
Runs Rough
Unstable
Erratic Idle
Stalling
Check Secondary Ignition System
Check Engine Vacuum
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAT Sensor
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EVAP Emission System
Check EGR System
Check For Oxygen Sensor Switching
Check O2 Sensor Heater
Check PNP Switch
Check PCM Power And Ground Circuits
Poor Fuel EconomyCheck Secondary Ignition System
Check Engine Vacuum
Check Fuel Pressure
Check ECT Sensor Calibration
Check TPS Calibration
Check MAP Sensor Calibration
Check IAT Sensor
Check IAC Motor Operation
Check The Minimum Idle Air Flow
Check EVAP Emission System
Check EGR System
Check For Oxygen Sensor Switching
Check O2 Sensor Heater
Check PNP Switch
Check PCM Power And Ground Circuits
Additional Information provided courtesy of
ALLDATAdiy.com and Warranty Direct
© 2000-2007 Vincent T. Ciulla

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