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Discussion Starter #1
Hello all, I believe this is my first post so apologies if I break any rules.
I have a 2008 dodge charger SXT, AWD, 3.5lt engine with near 200k miles on it. I mostly use it to go to the train station or to the supermarket, not a hard driver myself.
when this whole covid19 started I was left working from home and the car stored in the garage. One good day I heard a noise from one of the wheels and thats when my voyage of DIY started with my beloved car.
All was well until I decided to change the spark plugs and coils. I took the intake manifold out and changed the spark plugs (NGK zfr5lp-13g). I then reassembled everything the best I could following torque specifications for every spark, bolt, etc. I replaced the plenum gasket for a new one and the EGR tube gasket also for a new blue one. When I started the car I could hear a strange noise that I later identified as the classic vacuum leak sound, I also saw some smoke coming from the back of the manifold near the EGR tube and I saw the gasket was clearly not installed correctly and created the leak, maybe that was also the reason for the smoke??? Anyways the idle was very rough like about to stall and I got codes P2173 (vacuum leak), P0171 (system too lean bank1) and P0174 (fuel sustem 2/1 lean).....My thought was that I F***** the EGR tube.
So... I took everything out again, this time I even removed the windshield wipers to have more room, got a new EGR valve which I installed with its new metal gaskets and everything, I made sure the EGR gasket in the tube was in the correct position and followed/read plenty of tutorials and tips on how to install it into the plenum (Im waiting to get this red RTV to completely seal the connection between the plenum and the EGR tube just in case).... and so after some time installing all back again I started the engine once more....
Now the strange vacuum leak sound was gone but the engine had still this rough idle and I saw again some smoke coming from the EGR pipe area, after around 5 minutes the engine died and now I got codes P050B (cold start ignition timing performance) and P0300 (random/multiple cylinder misfire detected).
And now I’m clueless, if the vacuum leak had persisted I would have expected the same set of codes from the first try.
some things to note

  • electrical connectors were really frozen, I had a tough time disconnecting the ones near the throtle body
  • Maybe I have one bolt from the EGR tube not tight enough, I will try to tighten it tonight.

please help with any ideas
  • do I still have a major vacuum leak in the EGR?
  • did I f***** one of the connectors or sensors?
  • did I get a cheap plenum gasket and I have leaks in every valve now?
 

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Discussion Starter #3
Update 2: I removed everything again, up to the spark plugs again, cleaned them, torque to specs again, dielectric grease on the coils (I didnt do this before).
This time I gave the mating surfaces a deeper clean, EGR tube this time installed with red rtv for better sealing.....
.... the result?? Engine started the first try but still rough idle, no visible smoke from the engine or EGR, white smoke coming from the exhaust. I let it rum for a while then turned it off, waited like 10 minutes and tried again..... engine cranked but didn't start... now I have error codes P2172 and C121C. Its like at every try something gets fixed but something else gets busted.
Next try will include smoke evap test, voltage tests in every electric connector, new MAP and IAT sensors and cleaned throttle body
 

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P2172-HIGH AIRFLOW/VACUUM LEAK DETECTED
Set Condition:
A large vacuum leak has been detected or both of the TP Sensors have failed (TP = throttle position).
Possible Causes:
Vacuum leak
5-volt supply circuit shorted or open
MAP sensor
TP sensor (which is in the throttle body)


C121C-TORQUE REQUEST SIGNAL DENIED
Set Condition:
When the Anti-Lock Brake Module indicates if engine management for the Traction Control System can be accomplished.
Possible Causes:
Wiring harness/connectors
CAN Bus circuits shorted or open (CAN = controller area network)
ABS module

Your plan for a smoke test and to check/test the wiring harness/connectors is good. Checking the throttle body and MAP sensor also makes sense. The 5-volt supply to the sensors comes from the PCM.
..
 

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Discussion Starter #5
Last update: after removing and installing the manifold intake more times than I would like to disclose I finally did the following and it worked like a charm
  • installed EGR valve at specs torque, EGR tube loosely torqued to the valve in order to be able to move it back and forward
  • Installed manifold intake on top of the engine in the right spot but without torqueing the bolts just yet
  • If I moved the EGR tube at this point it didn't insert "gently into the manifold, so I had to tilt the intake a little bit in order for the tube to go inside it, gasket firmly in the tube second mark
  • Manifold back in correct position with EGR tube firmly inserted, no signs of the EGR tube gasket showing anywhere
  • Torqued everything to specs, including the EGR tube using a large extension
  • Engine fally working without vacuum leaks!! :):)
 
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