W209 CLK500 Spark Plugs recommendation

[aliharry]

Hi there,

One of my cylinders is misfiring in my 2006 clk500 (w209). I’m looking to replace the spark plugs and ignition coil packs as they will all need doing soon enough, what brand does everyone recommend as I believe ngk seem to do the best specifications for these cars.

Could anyone tell me which spark plugs are best (exact model/ part number if possible) and same with the Ignition coil pack

Thank you

 

[IanW]

I've been using NGK FR8DPP33+ plugs since I got the car 150K miles ago, changed every 50K miles or so. Shop around - they can be expensive, especially when buying 16 !
In 13 years I had one coil pack or corresponding leads fail. The coil was replaced with a Febi unit, the leads were replaced with Bosch items. If you replace the leads, be careful as they come in a variety of lengths.
Ian.

 

[Petrol Pete]

Hi OP , How many miles on the plugs that are in there now ? . have you identified which cylinder is 'missing' ?

 

[noogieman]

How do I know when a cylinder is misfiring as this has never happened to me before?
It's good to know how to spot a misfiring problem when or IF this occurs?

Drop in RPM, shaky engine on idle, loss of power on throttle?

 

[IanW]

How do I know when a cylinder is misfiring as this has never happened to me before?

In my case it was quite easy - the engine ran like it was about to fall out of the bottom of the car, the EML was lit and I had a fault code identifying the cylinder.
Additionally, the iCarsoft diagnostic tool has a function 'Engine Smoothness' that identifies cylinders that are not firing as well as the others. For example, only one of the two plugs per cylinder firing.
Ian.

 

[breeze247]

In my case it was quite easy - the engine ran like it was about to fall out of the bottom of the car, the EML was lit and I had a fault code identifying the cylinder.
Additionally, the iCarsoft diagnostic tool has a function 'Engine Smoothness' that identifies cylinders that are not firing as well as the others. For example, only one of the two plugs per cylinder firing.
Ian.

Can I ask which model iCarsoft tool and also what the exact function was called - was it called ‘smoothness’?

I have an i980 and it would be great if it did that.

 

[Petrol Pete]

How do I know when a cylinder is misfiring as this has never happened to me before?
It's good to know how to spot a misfiring problem when or IF this occurs?

Drop in RPM, shaky engine on idle, loss of power on throttle?

Use a scan tool , or change 16 spark plugs , 16 leads, 8 coils and the whole loom that feeds them. Or use a scan tool.

 

[IanW]

Can I ask which model iCarsoft tool and also what the exact function was called - was it called ‘smoothness’?

Mine is an iCarsoft 980 as well. You probably know where to find the function, but in case anyone else wanders this way courtesy of the search function, here's the full list.

Start by ensuring that the engine is running, up to temperature etc. you'll notice that not all iCarsoft diagnostics are available is the ignition is at position 1.
Turn the air conditioning/Thermatic/Thermotronic 'OFF' - it makes a difference!
Select 'Diagnose' NOT 'OBDII Disagnose'. Go through the vehicle selection process. You should now be at the menu that lists all the different modules found.
Select 'ME-SF 12.8 - Motor Electronics' (your ME version number may be slightly different).
Select 'Actual values' -> 'Check Smooth Engine Running' - check that the conditions are met - 'ESC' -> 'Preconditions Smooth Engine Running / Fault Counter' - check that the pre-conditions are met
'ESC' -> 'Smooth Engine Running' -> Look at items 641 onwards, which give angular accelerations for each cylinder. Watch the values for a while. Don't worry about those cylinders that flicker between 0 and +/-6 (I think that's the smallest unit). You're looking for a cylinder or two that consistently give numbers well outside the range of the others - anything up to 30 IIRC.
Replace the faulty coil pack(s), plugs, leads and re-test. Repeat until you're happy.
While you have the 980 hooked up, check the 'Falut[sic] Counter' group in the same menus. That should show counts for each cylinder that failed to fire at all - i.e. coil pack failure, or both plugs/leads duff.

I suspect that the A/C compressor is an uneven load - smoothness values improved noticeably when the A/C was turned off.

Ian.

 

[noogieman]

Use a scan tool , or change 16 spark plugs , 16 leads, 8 coils and the whole loom that feeds them. Or use a scan tool.

HA HA HA!
That's a very expensive solution swapping out all ignition parts at once.
Coil packs don't come cheap if all 8 fails!!

 

[ray_hennig]

Could anyone tell me which spark plugs are best

I get MB spark plugs. Guaranteed correct.

RayH

 

[Petrol Pete]

HA HA HA!
That's a very expensive solution swapping out all ignition parts at once.
Coil packs don't come cheap if all 8 fails!!

Exactly . Thats why I suggested using a scan tool....

 

[breeze247]

Mine is an iCarsoft 980 as well. You probably know where to find the function, but in case anyone else wanders this way courtesy of the search function, here's the full list.

Start by ensuring that the engine is running, up to temperature etc. you'll notice that not all iCarsoft diagnostics are available is the ignition is at position 1.
Turn the air conditioning/Thermatic/Thermotronic 'OFF' - it makes a difference!
Select 'Diagnose' NOT 'OBDII Disagnose'. Go through the vehicle selection process. You should now be at the menu that lists all the different modules found.
Select 'ME-SF 12.8 - Motor Electronics' (your ME version number may be slightly different).
Select 'Actual values' -> 'Check Smooth Engine Running' - check that the conditions are met - 'ESC' -> 'Preconditions Smooth Engine Running / Fault Counter' - check that the pre-conditions are met
'ESC' -> 'Smooth Engine Running' -> Look at items 641 onwards, which give angular accelerations for each cylinder. Watch the values for a while. Don't worry about those cylinders that flicker between 0 and +/-6 (I think that's the smallest unit). You're looking for a cylinder or two that consistently give numbers well outside the range of the others - anything up to 30 IIRC.
Replace the faulty coil pack(s), plugs, leads and re-test. Repeat until you're happy.
While you have the 980 hooked up, check the 'Falut[sic] Counter' group in the same menus. That should show counts for each cylinder that failed to fire at all - i.e. coil pack failure, or both plugs/leads duff.

I suspect that the A/C compressor is an uneven load - smoothness values improved noticeably when the A/C was turned off.

Ian.

Brilliant post.

Thank you.

 

[aliharry]

Hi OP , How many miles on the plugs that are in there now ? . have you identified which cylinder is 'missing' ?

Hi there, was told it was cylinder 3 misfire and my obd scanner confirmed this. The spark plugs and pack were changed yet it’s still misfiring which confirms it is the leads I believe but I’m not sure. Another weird issue is since getting it back after a when I drive it with any sort of heavy foot the engine light for misfire appears and all the dash lights come on the power steering and abs and electronics all stop working till I turn the car off and on again. I was told this could be the computer going limp mode due to the misfire ??

 

[aliharry]

How do I know when a cylinder is misfiring as this has never happened to me before?
It's good to know how to spot a misfiring problem when or IF this occurs?

Drop in RPM, shaky engine on idle, loss of power on throttle?

Fluctuations in rpm, shaky engine and loss of power are all symptoms yes

 

[BlackC55]

Hi there,

One of my cylinders is misfiring in my 2006 clk500 (w209). I’m looking to replace the spark plugs and ignition coil packs as they will all need doing soon enough, what brand does everyone recommend as I believe ngk seem to do the best specifications for these cars.

Could anyone tell me which spark plugs are best (exact model/ part number if possible) and same with the Ignition coil pack

Thank you

Don't forget the leads too. They are more common to cause misfires than anything else. ONLY buy genuine leads, nothing else.

 

[Dickster]

I get MB spark plugs. Guaranteed correct.

RayH

+ 1

 

[breeze247]

Don't forget the leads too. They are more common to cause misfires than anything else. ONLY buy genuine leads, nothing else.

When you say genuine leads, do you mean leads from a main dealer?

My understanding was that Mercedes don’t keep leads in stock (at least for the M113) and actually make leads up for you if you need them, using parts.

For my W209 CLK55 I did a lot of research and concluded that Beru leads were a high quality alternative. They may have been an OE supplier. Certainly they were on the expensive side compared to others. No issues once fitted and the quality was clearly better than what came out (not sure what was in the car previously).

 

[ray_hennig]

My understanding was that Mercedes don’t keep leads in stock (at least for the M113) and actually make leads up for you if you need them, using parts.

Yes. I had a set made up by MB in Bochum but have yet to install them.

I paid the extra because the recently procured Beru set felt of inferior quality to the 10+ year old Beru leads. The new ones were very difficult to snap on to the plugs and did not inspire confidence.

The old Berus are currently installed but the new ones will go in soon, together with the new MB cap, rotor, shield and plugs.

RayH

 

[breeze247]

Yes. I had a set made up by MB in Bochum but have yet to install them.

I paid the extra because the recently procured Beru set felt of inferior quality to the 10+ year old Beru leads. The new ones were very difficult to snap on to the plugs and did not inspire confidence.

The old Berus are currently installed but the new ones will go in soon, together with the new MB cap, rotor, shield and plugs.

RayH

Interesting! Any chance the new Beru leads were eBay fakes? Mine looked great and were solid. Definitely at the expensive end. From memory, around £200 when cheapest leads were around £40.

The last set looked like an old cheap set that somebody had then replaced leads on one by one, with newer leads that were still cheap.

 

[Gollom]

When you say genuine leads, do you mean leads from a main dealer?

My understanding was that Mercedes don’t keep leads in stock (at least for the M113) and actually make leads up for you if you need them, using parts.

For my W209 CLK55 I did a lot of research and concluded that Beru leads were a high quality alternative. They may have been an OE supplier. Certainly they were on the expensive side compared to others. No issues once fitted and the quality was clearly better than what came out (not sure what was in the car previously).

These look interesting - the guy makes them up to order

https://www.ebay.co.uk/itm/123967077713