Misfire

Tiny
SUMMER LEE DERRICK
  • MEMBER
  • 2003 CADILLAC CTS
  • 2.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 69,000 MILES
Hi I'm needing help I'm having problems with misfire that causes my check engine light to flash and then my car dies.
I have done the following to it to try to fix the problem:
1. Valve cover gaskets
2. Spark plugs
3. Coil packs
4. Fuel injectors
5. Thermostat
6. Mass air flow
And fixing to change knock sensor 2 will that solve the problem.
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Friday, June 14th, 2019 AT 7:11 AM

6 Replies

Tiny
KASEKENNY1
  • EXPERT
Hi Derrick,

Looks like you covered the most common causes. That helps limit down the possible causes. However, at this point we are going to need to see what the PCM is seeing that causes it to either add or remove fuel.

Also, we need to see if there are codes in the system and this will tell us which cylinders are causing the issue.

Next we need to go ahead and perform a compression test. If we have low compression on the cylinders that are misfiring then that will take us in a different direction.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/how-to-test-engine-compression

Please let me know when you get the codes and compression readings and then we will need to know what to look at in the PCM. Hopefully you have a scan tool that can look at live data. If not, more parts stores can pull the codes for you but they won't be able to look at data. But even if we just get the codes and compression we can hopefully figure something out. Thanks
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Friday, June 14th, 2019 AT 1:24 PM
Tiny
SUMMER LEE DERRICK
  • MEMBER
Would the knock sensor cause it? Because I'm not showing any misfire codes now. I know bank 2 on knock sensor can cause misfire. I'm replacing a bad water pump now and the knock sensor.
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Friday, June 14th, 2019 AT 7:00 PM
Tiny
SUMMER LEE DERRICK
  • MEMBER
My codes now are:
P0134
P0140
B15A6 fault a6
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Friday, June 14th, 2019 AT 7:04 PM
Tiny
KASEKENNY1
  • EXPERT
Okay. Great. Here are the code description for each of you P codes. The B code is an interior electrical code and not related to your flashing check engine light.

The P codes are your issue. Please review the steps to diagnose these closely because if the o2 sensors shorted out, then it could have damaged the circuit in the ECM and that will require replacement as well. More than likely you have a faulty o2 sensor because as you will see the ECM needs to see a difference in the upstream and downstream sensors. When it doesn't see a change in the upstream it sets the P0134. When it does not see a difference in the downstream it sets the P0140.

However, I just to make sure you don't just put the sensors in it and then it is still not fixed in the event it needs an ECM.

Lastly, you will need a scan tool in order to monitor the sensor data to properly diagnose it. If you don't have one, you could buy one, possibly find a friend with one, or have it looked at by a shop. Again, you could just put the sensors in it but without running through the tests you won't know if that is going to fix it.

Please let me know if you need more information. Thanks
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Sunday, June 16th, 2019 AT 9:31 AM
Tiny
SUMMER LEE DERRICK
  • MEMBER
I had my computer reset and down to.
P0332
P0135
P0134
I have the knock sensor being fixed now (p0332) which is low ( grounded out) so after this I'll just be down to 2 codes.
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Sunday, June 16th, 2019 AT 8:46 PM
Tiny
KASEKENNY1
  • EXPERT
Sounds good. Here is the diag for the P0135. I sent the P0134 earlier. Again, this may be a couple faulty o2 sensors but we need to run through the test.
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Monday, June 17th, 2019 AT 1:33 PM

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