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P0300 , P0174 codes

20K views 24 replies 4 participants last post by  Hobyz 
#1 · (Edited)
Hello, well i got this annoying problem today when i started my car after 5 minutes, car is idling very rough and its shaking, black smoke coming from tail, and suddenly it stalled.

I restarted the engine drove it back home but it was hesitating hardly any power.

After that i hooked up my diablo to check the codes and these codes appeared p300 random misfiring, p0174 system too lean bank 2.

My car is a 2010 charger r/t with LT American racing headers, cai, 180 stat , exhaust and cmr tune from johan.

I switched back to orginal factory tune problem went away..for now because i know it will come back again.

Im using 95 octane fuel on my car.

Any ideas?
 
#2 ·
"p0174 system too lean bank 2/1" will cause the PCM to compensate for the lean fuel ratio and increase the fuel ratio. A too rich fuel ratio will cause black smoke. The rich fuel condition then caused the cylinder misfire (P0300).


Check the O2 sensor and it's electrical connection/wiring. Bank2, sensor1 is the sensor being called out. (see illustration below).


If the O2 sensor is good, then the spark plugs, ignition coils, ignition wiring can cause it. Check the condition and connections on the ignition wires. Time for new spark plugs?
Also check the connections/wiring to the fuel injectors.


If all the above check out good, the ECT sensor (engine coolant temp) and the MAP sensor (manifold absolute pressure) can also cause the problem.


I assume 95 octane is because you live in a higher elevation.





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#3 · (Edited)
Thanks for the reply, well this isn't the first time it happens to me, it did before i changed all spark plugs cleaned TB, changed o2 sensor, camshaft sensor, map sensor.

So i still do not know what will cause this, didn't check for ect sensor though, havn't got CEL about it.

Will a bad throtte position sensor cause this ? Or will an exhaust leak near the o2 sensor also cause this? Or maybe IAT sensor?

Because this like the second time its happening and at the same bank, i've changed the o2 sensor two times already same place..whenever i change the o2 sensor the car goes back to normal, after driving it couple of miles same problem comes again same bank..
 
#4 ·
A exhaust leak near the o2 sensor can cause problems. The IAT sensor is one of the inputs the PCM uses to determine AFR (air-fuel ratio). I would look at the possibility of an exhaust leak - especially since you're only getting a couple of miles out of a new O2 sensor. Something is destroying the O2 sensor. Could be an exhaust leak or the wiring/connector to the O2 sensor.


How do the electrodes on the spark plugs look? Normal, black sooty, black wet ?
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#5 ·
I checked for exhaust leak, there are none as exhaust shop told me.

I just changed the wiring/connector it doesn't seems fired or something but it could be problem the mechanic told me wires looks mushy thats due to heating, i don't know if thats a problem but car runs fine after replacing o2 sensor with the wire plug.

About the spark plugs it did looks black sooty before i changed them but the mechanic told me its only on passenger side where bank 2 o2 sensor is located, but i replaced them all eventually.

Thanks djablin for the help, if you could check this thread if you have any idea about it.

http://www.chargerforums.com/forums/showthread.php?p=4098106
 
#6 · (Edited)
OK, so you replace parts, I assume you are clearing the computer by disconnecting the battery? Doing this sets the computer back to base program and zeroes out the short term and long term trims, as does reloading the factory computer.




You have headers on the car, and have verified no leaks.

You start the car fine, drive it fine for a few miles, then it starts acting up with a lean bank code on Bank 2.

You replace the O2 sensor, and the problem returns.

You are seeing a random misfire, presumably due to the lean code causing that bank to be forced too rich.

I suggest that you run the headers, examining all wiring harnesses within 6 inches of them. That the car runs fine for a few miles tells me that the problem is a closed loop problem, and the only sensor input change (that I am aware of, anyway, not too familiar with Dodges yet) is the computer starts using the O2 sensors. When the car is cold it runs open loop, which means it uses a defined table for the fuel/air mix. When it goes closed, it starts adjusting the mix according to the O2 sensors. Long tube headers change the exhaust path from the engine to the rear of the car and may be taking it too close to a harness. Or, those harnesses aren't riveted to the car every half inch, they are only held on at set points and highway speed airflow can cause a harness to move quite a bit further than you might expect particularly if one of the few plastic attaching pins is broken. Over time, a wiring harness that is hitting a 600 degree exhaust WILL melt through loom and through insulation, then will short the wiring out. I've been through this EXACT problem before, only on a pickup truck, and the problem is the harness sat away from the headers when parked on my ramps but highway speed wind was pushing it several inches over until it hit the header. Admittedly this is a long shot, but you never know. I wouldn't worry about how long the headers have been on either, all it would take is a wiring attach point coming loose to cause the problem.

In addition, I'd check the inside of the O2 sensor on the car side, to make sure there's nothing wrong in there. Something is shorting that sensor out, causing it to read lean.
 
#8 ·
Yea thats exaclty what i've thought of, i did replaced the wiring now with a brand new oem o2 sensor, like i said the mechanic guy told me it could be the wiring causing this, i also noticed that i don't have the belly pan under the car installed, i've red before not having this belly pan might cause some heat? I don't know if that would be the problem? car seems to run fine for now and i hope it does, ill drop the car later on at some garage shop to check my engine for any leaks, problems, cleaning everything, etc.

Thanks for the help i appreciate it.
 
#9 ·
I don't mean the wire that comes with the O2 sensor, I mean the wiring the sensor plugs into on the car's harness. If that's damaged then no O2 sensor in the world will work correctly. What's worse, if the damage is just right it might work today but not tomorrow, depending on whether or not the damaged sections are touching either a ground point or each other.
 
#13 ·
Very good, that was the best solution.

Unfortunately, I am also out of ideas, other than to recheck all wiring harnesses on top of the engine as well to make sure that everything that might have been disconnected when the headers were installed was plugged back in (assuming the headers are new), or anywhere you did work just prior to this problem coming up, as it is easy to miss a plug when putting it all back together.

Good luck with it, and if anything else occurs to me I will post up. I still think you have a closed loop problem based on your driving experience posted.
 
#15 ·
During OPEN LOOP operation the PCM receives input signals and responds according to preset PCM programming. Inputs from the upstream and downstream heated oxygen sensors (O2S) are not monitored during OPEN LOOP operation, except for heated O2S sensor diagnostics (they are checked for shorted conditions at all times).
During CLOSED LOOP operation the PCM monitors the inputs from the upstream and downstream heated O2S sensors. The upstream heated oxygen sensor input tells the PCM if the calculated injector pulse width resulted in the ideal air-fuel ratio of 14.7 to one.


The upstream sensors’ main function is to monitor the air fuel ratio coming directly out of the engine. The downstream sensors' primary task is to monitor how effectively the catalytic converter is working. When a catalytic converter is working properly, the downstream oxygen sensor will output a relatively steady voltage of about .5 volts. If the converter is going bad, the voltage coming from the downstream sensor will be almost identical to the voltage coming from the upstream, which fluctuates between .2 and .8 volts while the engine is running.
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#16 ·
During OPEN LOOP operation the PCM receives input signals and responds according to preset PCM programming. Inputs from the upstream and downstream heated oxygen sensors (O2S) are not monitored during OPEN LOOP operation, except for heated O2S sensor diagnostics (they are checked for shorted conditions at all times).
During CLOSED LOOP operation the PCM monitors the inputs from the upstream and downstream heated O2S sensors. The upstream heated oxygen sensor input tells the PCM if the calculated injector pulse width resulted in the ideal air-fuel ratio of 14.7 to one.


The upstream sensors? main function is to monitor the air fuel ratio coming directly out of the engine. The downstream sensors' primary task is to monitor how effectively the catalytic converter is working. When a catalytic converter is working properly, the downstream oxygen sensor will output a relatively steady voltage of about .5 volts. If the converter is going bad, the voltage coming from the downstream sensor will be almost identical to the voltage coming from the upstream, which fluctuates between .2 and .8 volts while the engine is running.
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So you're saying that it could be the converter goin bad? I checked at the exhaust shop hasn't told me if there something wrong with it, but i don't know how it would go bad or not, im running LT headers with no cats.
 
#17 ·
Not necessarily. Closed loop means it adds the sensor inputs from the O2s in, and makes adjustments accordingly. Back in the old OBD1 days when one sensor controlled both banks a closed loop problem affected the entire engine, but now it only affects one bank. Since it is only affecting one bank, it will be limited to a problem with sensors on just that bank, ignition on just that bank, or fueling on just that bank. If it's going lean as soon as it goes closed loop, something is wrong in this area.

On the program, did he check all parameters including long and short term trim fuel adjust values? There should be several fields that control how the trim adjusts and if there is an error here then it might be weighting trim to the lean. It's not something people generally adjust when doing tunes, but it's possible that he changed a wrong field without noticing. That it's only making one bank go lean makes this a possibility. The quickest way to check would be for him to do a compare between the factory tune and the existing tune, if the program allows it.

It might also be time to take it to the dealer for a diagnostic.
 
#20 ·
Well like i said car is custom tuned by johan he's pretty known for custom tuning these cars, i did sent him some logs and he told me there was no issues with the tune that's before the problem occurred, i also did sent him logs with stock tune and nothing wrong with fuel, i also did a dyno run with the custom tune running and fuel/air ratio were fine, BUT the only problem im getting now is a knock, i'm getting around 4.5 to 5 knock and thats happning both on the custom tune and stock tune.
 
#18 ·
it could be the converter goin bad? im running LT headers with no cats.
If you eliminated the cats, but still have the downstream O2 sensors, the downstream sensors will think the cats are bad and post a DTC. There is nothing to fix with the missing cats, or downstream sensors, if you have a custom tune that prevents the DTC being posted.
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#19 · (Edited)
it could be the converter goin bad? im running LT headers with no cats.
If you eliminated the cats, but still have the downstream O2 sensors, the downstream sensors will think the cats are bad and post a DTC. There is nothing to fix with the missing cats, or downstream sensors, if you have a custom tune that prevents the DTC being posted.
.

I do have custom tune by johan, but the main problem actually comes from the upstream sensor side, and thats just one side actually the passenger side
 
#22 ·
A bad sensor, yes. Multiple, no. However, simple test, the driver side sensor has been good all along, yes? Swap sides, move the passenger sensor to the driver side and the driver side to the passenger side. If it is a sensor problem, the lean condition should move to the driver side.

Which brings up another question, what O2 sensors, factory or Bosch? If Bosch, there's your problem. Non-OEM brand electrical sensors rarely work well.
 
#23 ·
They're OEM, driver side sensor is fine actually and i haven't changed it ever, car is running fine for now and i hope it stays fine, like i said the problem could be of the harness itself so it has been replaced and i hope the problem does not come back again, thanks for the help man i appreciate it.
 
#25 · (Edited)
Just wanted to bump this thread for future help for anyone who might could have the same problem as mine.

I just figured out what was the problem it was the valve gasket were going bad, i changed them and car runs so MUCH better ! I found out on the right side valve gasket are bad which is making it leak causing the o2 sensor on the right side to go bad.

So if you got this problem again even after replacing your o2 sensor change your valve gasket, and check for any oil leaks.

I also changed the intake manifold gasket with new OEM's, the valve gasket with victor reinz gaskets (i heared they are OEM quality and even could be better) also changed the pcv valve, crankshaft sensor, knock sensors & transmission oil filter, and thanks to god car now runs so much better and i hope its stays like this.
 
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