Chrysler PT Cruiser 2001 Service Manual Supplement page 2562

DRIVEABILITY - GAS
P0300-MULTIPLE CYLINDER MIS-FIRE —
TEST
4 Note: Anything that affects the speed of the crankshaft can cause a misfire
DTC.
The following are other possible causes for mis-fire:
Injector harness connectors, secondary ignition problem, mechanical engine problem,
PCM power grounds, irregular cam and crank signal, plugged injectors, restricted
exhaust, intake restriction, damaged trigger wheel, contaminated fuel, or vacuum
leak.
Weak valve springs, carbon deposits on valves, or accessory drive belt (serpentine
belt).
Check for any TSB's that may relate to a Misfire DTC.
Do any of the above causes exist?
Yes → Repair as necessary.
→ Go To 5
No
5 With the DRBIII , read the FREEZE FRAME DATA.
Use the FREEZE FRAME DATA and attempt to determine the cause of the Misfire
DTC.
In the FREEZE FRAME, are the adaptive fuel percentages greater than +/- 15%?
Yes → Refer to the Driveablitiy Category and perform the Checking Fuel
→ Go To 6
No
6 With the DRBIII , read the FREEZE FRAME DATA.
Use the FREEZE FRAME DATA and attempt to determine the cause of the Misfire
DTC.
In the FREEZE FRAME DATA, is the LOAD VALUE over 50% and the operating
temp normal?
Yes → Check secondary ignition, compression, and cylinder leakage.
→ Go To 7
No
7 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?
Yes → Repair as necessary.
→ Go To 8
No
ACTION
Perform POWERTRAIN VERIFICATION TEST VER - 5.
Delivery symptom.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
Continued
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APPLICABILITY
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