2002 WS6 - p0300 - Random Misfire
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Teching In
Joined: May 2006
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From: Jefferson, WI
2002 WS6 - p0300 - Random Misfire I have an 02 WS6 that started having this issue. After winter hibernation I noticed this a few times, but went away. Now this is consistent and I am getting the p0300 code. At idle it is running rough and as I bring up the RPMs (while not driving) it just becomes more noticeable. I thought it was maybe the system is running rich, but it seems the rich smell is from the misfiring.
New Fuel pump, I checked for vacuum leaks, I sprayed water on the plug wires (MSD 8.5s) and there seems to be no spark leak. O2s were replaced as well.
I have HP Tuners software, but cannot figure out how to show what cylinders are misfiring.
Any thoughts or help would be appreciated before I start pouring money into the car. My next option is to reseat the plugs on the PCM since I was told it controls the spark.
New Fuel pump, I checked for vacuum leaks, I sprayed water on the plug wires (MSD 8.5s) and there seems to be no spark leak. O2s were replaced as well.
I have HP Tuners software, but cannot figure out how to show what cylinders are misfiring.
Any thoughts or help would be appreciated before I start pouring money into the car. My next option is to reseat the plugs on the PCM since I was told it controls the spark.
Thread Starter
Teching In
Joined: May 2006
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From: Jefferson, WI
Well I tried reseating the following electrical plugs: plug wires, Injectors, PCM, TPS, MAF and no change. I ran the car at 2600 and took temp readings off of the headers of each cylinder and got temps from 190 to 450. Seemed the average temps were about 370 deg. 1, 4, 5, and 6 seemed to be a lower temp ( by 100Deg +) So I left it running at about 3K and noticed the headers on the driverside started glowing they were so hot. The passenger side did not seem to be glowing. WTF......
Thread Starter
Teching In
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From: Jefferson, WI
My next step is replacing plugs and wires. Easiest and it has been 65K since they were last replaced. I am considering the crank sensor next.
I will most likely put Iridiums back in, but I have heard that some people are using copper plugs and are getting the same power if not more. I am sure there is a comparison on the Internets to prove one or the other.
I will most likely put Iridiums back in, but I have heard that some people are using copper plugs and are getting the same power if not more. I am sure there is a comparison on the Internets to prove one or the other.
Thread Starter
Teching In
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From: Jefferson, WI
Well new plugs and wires were installed and there was no change <sigh>. The odd thing that I found was Bank 1 the plugs looked perfect. Bank 2 all the plugs were black as night. So I am guessing bank 2 is either getting too much fuel or the misfire is just that side. I am guessing that I might have a bad O2 Sensor or a bad PCM/ECM. The frustrating thing is that O2 sensor was replaced 2 times. I replaced both in October of 2013 and after the winter I was getting a code Heater circuit failure which indicates a bad O2. I replaced it and the car ran good again. 3 O2 failures in a year is frustrating.
Thread Starter
Teching In
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From: Jefferson, WI
I think I might have found the issue. I connected my HP Tuners up and Bank 2 Sensor 1 (O2 sensor) was not responding. Bank 1 Sensor 1 was had a good Wave Pattern from 900+ mv to 50 mv. Bank 2 Sensor 1 was a flat 10 mv and once the computer went into close loop the voltage went to 2 mv. My fuel trim for Bank 2 was through the roof.
New O2 sensors ordered. Going to swap them tomorrow to make sure the issue follows the O2.
Oh and no effing code was tripped that the Sensor was bad..... Stupid Sensors....
New O2 sensors ordered. Going to swap them tomorrow to make sure the issue follows the O2.
Oh and no effing code was tripped that the Sensor was bad..... Stupid Sensors....
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Teching In
Joined: May 2006
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From: Jefferson, WI
I switched the O2s and the issue following the O2 that was on Bank2 over to Bank1. So as of now the issue seems to be a faulty O2. My fuel trim normalized on bank2 and Bank1 fuel trim went through the roof.
I ordered 2 new O2s with the plug attached so they do not have to be wired to the car.
The new O2s should arrive today or tomorrow.
I ordered 2 new O2s with the plug attached so they do not have to be wired to the car.
The new O2s should arrive today or tomorrow.
Thread Starter
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From: Jefferson, WI
Ok.......So new O2s arrived and were installed. Issue fixed so far. I connected up my HP Tuners and the O2s have good patterns and the fuel trim is back to normal.
I took her out and ran it hard. Pulled hard up to 5500 and no detonation. Looks to be back to normal.
Time for a wash and wax for the weekend!!
I took her out and ran it hard. Pulled hard up to 5500 and no detonation. Looks to be back to normal.
Time for a wash and wax for the weekend!!
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Joined: Aug 2010
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From: Ann Arbor, MI
Let me translate that:
I searched forever - with me it was 2 defective coils.
Replaced them with AC Delco Performance coils.
---------------------
Welcome to the forum.
Hopefully you will find it useful, although it is all in English.
I searched forever - with me it was 2 defective coils.
Replaced them with AC Delco Performance coils.
---------------------
Welcome to the forum.
Hopefully you will find it useful, although it is all in English.