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Got the codes read: P0300, P0304, P0305, P0306

31K views 29 replies 6 participants last post by  Michael Pillay 
#1 ·
My OBDII scanner arrived today and the I got the following codes:

P0300, P0304, P0305, P0306

Having elimated the following:

1. Bad gas. Pulled off the expressway and filled up when the vehicle started to have problems.
2. MAF- removed and cleaned with CRC Mass Air Flow Sensor cleaner
3. Oxygen Sensors- replaced all 4

This leaves me with the following:

4. Spark Plug wires and plugs
5. Catalytic converter. I'll assume passenger side since cylinders 4,5,and 6 misfired. (4,5,and 6 is one the passenger's side...right????)

For those of you who have had to deal with this before, could it just be the plugs and wires? If you think that it is sure to be the cat, any idea where I can buy a new one? Thanks

I have included a link to my original post so that someone else who has this problem will have less searching to do.

http://www.benzworld.org/forums/w163-m-class/1295685-need-help-will-not-drive-over-25mph.html
 
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#2 ·
It seems to be a clue that all of your misfires are on one side PO304-Cylinder4, PO305-Cylinder5 and PO306-Cylinder6. I would look into the possibility of an electronic problem such as the coils that the wires plug into.
 
#12 ·
sorry.
http://i68.tinypic.com/spb41y.jpg
http://i66.tinypic.com/35mgwuq.jpg

Those are readings on stopped truck on traffic light or parking, but at 50km/h speed it's similar. Car is working very unstable on idle, and a little better, but still bad, at driving.
Also, I'm running petrol/LPG, truck works similar on both.

Yesterday I've reseted errors after replacing maf. Should I drive like 30 minutes on 90km/h and then make screenshots of torque?

EDIT:
I have new reading from 10km ride to work. Probably I should heat my engine outside of city, right?
 

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#13 ·
Scroll up screen so value at the top starts with STFT1 and throttle position at the bottom. With engine at operating temperature make few runs with 100% throttle. Have assistant take screenshot just before 2-3 shift. Do it few times so we have more samples.

Was replacement MAF genuine Bosch product of fake in Bosch box? Your LTFT2 value is at the lean stop. Engine is getting too much fuel or not enough air. Blocked exhaust will cause poor air flow.

 
#14 ·
Scroll up screen so value at the top starts with STFT1 and throttle position at the bottom. With engine at operating temperature make few runs with 100% throttle. Have assistant take screenshot just before 2-3 shift. Do it few times so we have more samples.

Was replacement MAF genuine Bosch product of fake in Bosch box? Your LTFT2 value is at the lean stop. Engine is getting too much fuel or not enough air. Blocked exhaust will cause poor air flow.
Bosch MAF was replaced from another 3,2l working MB. Isn't my LTFT reading frozen, because car is working only at closed loop? I will heat engine and then make testes with 100% throttle.
 
#19 ·
You are not the first member to post very similar problems when running on LPG.

Glad it is working fine on petrol. When you have the time to look into replacement/rebuilding or cleaning of the LPG injectors see if you can find the original shop that did the conversion to LPG.
 
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