Mercedes-Benz Forum banner

1 - 20 of 30 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter #1
1999 ML430

Getting code P0305 - cylinder 5 misfire

New spark plugs
Fresh oil change
New air filter
Professionally cleaned & balanced injectors
Compression on cylinder 5: 175
Compression on cylinder 6: 178
Resistance on spark plug wires ~2.2k ohms
Switched coils 5 & 6

Still getting code... what should I check next???
 

·
Registered
Joined
·
6,647 Posts
Is it just setting code or actually misfiring? Is CEL flashing? Swap injectors, swap ignition wires. Wires may check OK with ohm meter but that does not eliminate insulation breakdown.
 

·
Registered
Joined
·
19 Posts
Did you try swapping plug wires and plugs 5to 6?
I had a simmilar problem where i had a intermittant miss at idle for over a year before it finally set a code indicating #5 miss...i swapped #5 coil,wires and plugs from #5 over to #2 and even though everything looked/tested fine this cured the miss never missed since and never a fault code(over a year ago)...go figure..but if you have faulty plugs or wires when you swap over fault code should follow...Id swap wires and plugs if code follows then you can determine which are faulty...if not then you know its not coil, plugs or wires...
 

·
Registered
Joined
·
31 Posts
Discussion Starter #4
Swapped almost everything... no luck.. new codes

Coils, wires, & injectors have all been swapped. I still have code P0305 - misfire in cylinder 5.

I drove the ML430 a few miles and 2 new codes came up, P0156 & P0161.

These new codes point to the bank 2,2 post cat oxygen sensor.

I will be swapping the left and right side oxygen sensors to see if there is a change.


Any other ideas????
 

·
Registered
Joined
·
19 Posts
Catalitic converter failure/plugging
you could swap o2 sensors around to verifiy code follows , but should really check cat or get checked b4 doing much else..
 

·
Registered
Joined
·
31 Posts
Discussion Starter #6
Switched post cat oxygen sensor - new codes

Still getting 0305 (cylinder 5 misfire) but now I have 0300 (random misfire) & 0141 (bank 1 post cat)

I am planning on replacing all 4 O2 sensors since they all have 110k miles on them.

I am still baffled why I am getting a specific misfire on cylinder 5.
 

·
Purple Moderator
Joined
·
21,705 Posts
Be careful as the generic OEM Bosch sensors have given people trouble.
Get the specific Bosch numbers for your truck. The front two are the same number
and rear two are the same number. (however the front and rear are not the same numbers)
Front:2 of Bosch # 13782 (Amazon is the lowest at $65 apiece free shipping)
Rear: 2 of Bosch # 15202 (Amazon is the lowest at $80 apiece free shipping)
The dealers want nearly $200 apiece for them and they are identical to the Bosch.
Bosch makes them for MB.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #8
Bosch website says front & rear are the same PN

Their website says 15202 for front and rear.

NGK/NTK states that 25567 will work for front & rear as well.

???
 

·
Purple Moderator
Joined
·
21,705 Posts
It is wrong. I have been through this several times.
Look them up on autohausaz.com

It is your truck and you can put in what you want I am just telling you what is out there.
Why would MB still list two different numbers as current if all four were identical?
MB # for Fronts: 001 540 60 17 ($204 apiece)
MB # for Rears: 001 540 37 17 28 ($398 apiece)

You can dig back through the forums and see what happens when members used all four
of the same. And I would take the Bosch over the NGKs.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #10
Do you know the difference between the to PN's?

Are they totally different sensors or is the wire length different?

Here are the numbers off the post cat O2

001 540 28 17
 

·
Purple Moderator
Joined
·
21,705 Posts
001 540 28 17 is still available at $228
Your vin must be close to mine. I had the same number.
See attached screen capture from MBs EPC Net. You
will see the parts boxed in red. Item #14 and 17. I used the Boschs
that I listed (as have many others) and they worked perfectly.


The internals are different from front to rear.
On the Bosch 15202s the cables are all the same length.
On the correct fronts and and rears there is a difference in length.
 

Attachments

·
Registered
Joined
·
31,633 Posts
I would agree with changing the O2 sensors, but have a couple of other thoughts as well.

Did they remove the injectors when they cleaned them or just do the pressurized-rail treatment? Nothing wrong with pressurized-rail cleaning, but it is also possible you have a leak at one of the injectors; o-rings can and do fail. It's easy enough to reseal all of them, just be sure you clean things up before you take it apart, very easy for dirt to drop in those openings.

The other thing is that this may not actually be #5. I had a slight miss I could feel for a long time and the car finally set a P0303 code (M112 engine). I tried the swaps and no effect and finally ended up replacing the ignition wires (hunch? dumb luck?) when I was doing some other work. I marked the wires as I removed them just for the heck of it, and when I started it up the miss was gone. When I later tested the wires I found that one of the wires on #4 was beyond spec for resistance. So basically the stored code was for the wrong cylinder. (Lovely...sigh.) So test/inspect everything, not just #5, and consider resealing the injectors, too.

Good luck.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #14
O2 sensors etc

I removed the fuel injectors and had them balanced and blueprinted at RC Engineering. They also installed new seals. On the install I made sure they were clean and went in smooth.

I am picking up 4 Bosch 13782 O2 sensors today. I spoke to Bosch this morning and they sais the 15202 is not being made any more and the 13782 is the new part for front & back.

Next step.... install O2's and see if some issues go away. If it does not help I will then be installing new plug wires and moving around my coils.

Lots of fun!!!
 

·
Registered
Joined
·
31,633 Posts
What do you recommend for spark plug wires?

There are a lot of options out there.
Replacement Bosch are great and come with a lifetime warranty. When I bought mine Amazon had the best price, and though they were in stock they took almost a month to receive. :rolleyes:
 

·
Registered
Joined
·
31 Posts
Discussion Starter #17
New O2 sensors.....

New O2's but still have misfire condition and code 0305.

I am ordering new wires... I have had suggestions to replace the MAF.

Still a little stumped.
 
1 - 20 of 30 Posts
Top