22:16:31 - 12/07/2023
Subject: 2002 Sport 3.9l Intermittent Misfire|
Greetings from the Yukon, Canada.
My daughter's 2002 Sport has had a long standing
issue. When she bought it at 118,000 km it would
occasionally bog/pop out of the throttle body in
town or on a hill. Give it a little gas and it
would clear up and be fine. Now at 150,000 km some
days it will run perfect as new, but then the
issue will show up. It is now every day or so.
Loses power, engine shakes, general misfiring.
Pull it over and mess with the PCV Valve, and it
will clear up and be fine.
Codes are always the same...#3 Cylinder Misfire,
#5 Cylinder Misfire, Multiple Cylinder Misfire,
P0172 Running Rich, and P0132 O2 Sensor High
Circuit Bank 1 Sensor 1 Upstream.
All new Champion Copper Plugs, Brass Cap, Rotor,
New Plug Wires, IAC Valve, TBS, ALL 3 CATS are
gutted, Trans. fully rebuilt Fall 2021, Multiple
vacuum leaks fixed/ hoses replaced, etc. PCM also
checked and cleaned connections.
Have tried to locate a genuine Mopar PCV valve to
no avail. Have tried the ones I can find, Fram and
Standard. Looked into the Plenum and only a slight
residue from a past PCV issue. Looks like the
Plenum gasket was done in the past. Cannot find
any more vacuum leaks. Maybe a clog?
All old plugs all looked great and normal.
When it runs well I mean it runs better than new.
Can go a day, 2 days, even a week at times...but
then the issue hits. Dangerous to pull out into
traffic when it acts up. No stalling or hard
Ideas I have are the upstream O2 Sensor itself,
Coil, Crankshaft Sensor, Cam Sensor, PCV valve
wrong pressure, EVAP Leak or Clog, Water in gas.
Fuel pump has checked out fine many times.
Any success stories with this issue. Fix stories?
| RE: 2002 Sport 3.9l Intermittent Misfire|
I had very similar issues to include very high
rpms, as if the transmission was faulty. I had
two issues and now she runs great. The first was
faulty intake gaskets (P0174), when I removed I
noticed no gasket silicone on the 4 corners (I
bought it with 130K miles). I replaced as Mopar
recommended and all's well there. I ran the truck
and the symptoms returned but different code,
P0152, I replaced bank 2 upstream 02 sensor and
she runs great! For the 02 sensors it helps to
have a ODB2 reader that graphs thier voltages,
I was able to compare them and see the problem,
and it was intermittent. Good luck.
| || P 1|
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