Misfires on all 12 Cylinders? '07 CL600 w/78k miles
Thread Starter
Senior Member
Joined: Oct 2004
Posts: 433
Likes: 9
From: Phoenix, AZ
2007 CL600
Misfires on all 12 Cylinders? '07 CL600 w/78k miles
I'm getting misfire codes on all 12 cylinders. Plugs replaced with factory recommended. Voltage Transformer + one coil pack replaced from v12icpack.com. The other replaced about 15K miles ago with OEM coil pack. Car recently coded to replace right side cat which was replaced with new O2 sensors. Does anyone have any thoughts on what would cause misfire codes on on 12?
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Joined: Feb 2012
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From: Phoenix
222 S-65
Do you have access to XENTRY?
Good place to start.
You live in the desert. Look for evidence of our little friends (rodents) having had their way with wiring.
Replaced a crankshaft position sensor? Those should get replaced every 4-5 years just because. It can make a no code failure.
Good place to start.
You live in the desert. Look for evidence of our little friends (rodents) having had their way with wiring.
Replaced a crankshaft position sensor? Those should get replaced every 4-5 years just because. It can make a no code failure.
Thread Starter
Senior Member
Joined: Oct 2004
Posts: 433
Likes: 9
From: Phoenix, AZ
2007 CL600
Thanks for your response. I've no access to XENTRY.
I wanted to check the connection to voltage transformer and disconnected the battery. I did little more than disconnect and reconnect the battery. When I reconnected the battery and tried to start the car, the starter turned but the car would not fire up. I'm having the car towed to a specialist this week to get it sorted. That might be a good time to replace the crankshaft position sensor.
I wanted to check the connection to voltage transformer and disconnected the battery. I did little more than disconnect and reconnect the battery. When I reconnected the battery and tried to start the car, the starter turned but the car would not fire up. I'm having the car towed to a specialist this week to get it sorted. That might be a good time to replace the crankshaft position sensor.
Last edited by WIldcat465; Dec 4, 2024 at 12:21 AM.
MBWorld Fanatic!
Joined: Feb 2012
Posts: 2,608
Likes: 1,208
From: Phoenix
222 S-65
Thanks for your response. I've no access to XENTRY.
I wanted to check the connection to voltage transformer and disconnected the battery. I did little more than disconnect and reconnect the battery. When I reconnected the battery and tried to start the car, the starter turned but the car would not fire up. I'm having the car towed to a specialist this week to get it sorted. That might be a good time to replace the crankshaft position sensor.
I wanted to check the connection to voltage transformer and disconnected the battery. I did little more than disconnect and reconnect the battery. When I reconnected the battery and tried to start the car, the starter turned but the car would not fire up. I'm having the car towed to a specialist this week to get it sorted. That might be a good time to replace the crankshaft position sensor.
Senior Member
Joined: Dec 2019
Posts: 406
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From: Houston, TX
2005 SL600
Seeing that your ignition system should be good, I'd look for an air leak in the intake tract somewhere behind the MAP sensors. This would cause an excessively lean condition in all 12 cylinders. The system should detect the lean condition via the O2 sensors and try to compensate, but it's still not going to run entirely right while there's air entering the engine that is not accounted for by the MAP sensors. Possibly a crack in the intake boot, or the intake boot might be slightly misaligned. Check vacuum lines as well.
MBWorld Fanatic!
Joined: Feb 2012
Posts: 2,608
Likes: 1,208
From: Phoenix
222 S-65
Seeing that your ignition system should be good, I'd look for an air leak in the intake tract somewhere behind the MAP sensors. This would cause an excessively lean condition in all 12 cylinders. The system should detect the lean condition via the O2 sensors and try to compensate, but it's still not going to run entirely right while there's air entering the engine that is not accounted for by the MAP sensors. Possibly a crack in the intake boot, or the intake boot might be slightly misaligned. Check vacuum lines as well.
OP certainly using smoke to find any intake leaks is good practice.
Were there an intake leak you will find the throttle body further closed than normal to make idle speed and low speed fuel trim to be off.
A boost leak will be clearly audible as the turbos try to make boost.
OP have you replaced a crankshaft position sensor yet?
That sensor looks eerily similar to the CPS used in the bent eight K engines that are known for failing to all manner of mischief without a code.
Oh.... Most common way the CPS fails is ‘Engine cranks, does not start.’
Last edited by JohnLane; Dec 7, 2024 at 03:36 PM.
