hadam

Today while driving in city I got CEL with message on display "Engine Electronics".

I went to Autozone and read the Code and it came out as following.


P0308 Cylinder 8 Misfire Detected



My car is 1997 E420 and now has 130K miles on it.

I believe I need to put new plugs and change wires.

Any body think of any other reason that I should replace MAF or O2 sensors?

How much plug and wire/ignition coils cost? Is it DYI kind of job?

Any one know what type of plug should I buy for 1997 E-420 and part number for coil/wires.

Thanks in advance for your reply and feed back from all W210 fanatics.

citruspilot

Well, I have had the same code in the past. I replaced the coil and spark plug in the particular cylinder then cleared the code. It never came back. Not a hard fix at all. I think I paid around $65.00 for the coil from MB and the spark plug was like $3.00. Dont remember the brand plug I installed but the coil is Bosch. You can put it in or have it installed by a mechanic in about half an hour.

Good luck.

Jeff

Racin_fool

just call the local dealership and ask the parts guys what brand is recommended from the factory for the spark plugs.

As for the wires, thats your choice.

Replacing the spark plugs and wires takes care of most misfire problems.

Musikmann

I would not replace the MAF or O2 sensors unless/until you get an error code for those (both will create a CEL message too); I think you're talking about throwing $1000 at your car by doing that. Will they eventually go bad? Probably, but I would wait on those if I were you.

If you don't know how many miles are on your plugs/wires I'd start there, or as citruspilot suggested, zero in on your #8 cylinder.

hadam

Hi, all thanks for reply.

Today I went and changed all 8 spark plugs and reset the Code and started car, but I got again Code P0308.

This tells me that this must be bad coil issue then. I will go ahead and install new coil on Cylinder 8.

Do you know which one is cylinder 8, it is back on driver side (next to master brake module) or passenger side (next to controller moudle)?

see the photo and please let me know.

hadam

Yester day I installed the new plugs, then I reset the code. I started the car and got again code P0308.

Today I will install new coil on Cylinder 8.

Can someone tell me which one is Cylinder 8?

Is it one close to Firewall on driver side (Next to master brake unit) or the one close to Firewall on passenger side?

Racin_fool

#8 is the one on the drivers side, closest to the firewall.

try swapping that coil over to a different cylinder and see what happens. Also, take a look at the end of the black sleeve that fits down over the spark plug. If the end of it is all torn up and cracked, I would suggest replacing that suppressor end and see how that works.

citruspilot

Heres the solution. Go buy a new Bosch coil. Remove the cover off the head and pull the coil off the #8 cylinder, back by the drivers side firewall. Put your new coil in its place. Reinstall the cover. Start the car. Drive the car. "IF" your coil replacement stopped the engine miss then your done simple as that. Dont worry about resetting the computer or clearing the code. After you drive it for a good bit stop the car and shut the ignition switch off. Restart the car. The computer will do a "driveability check" and if everything is hunky dory it will automatically clear the code itself. You may have to drive it 30 or 40 miles and shut it off a few times but it will clear itself. How do I know this. I did it just the other day to mine and this is "exactly" what mine did. Total cost was around $75.00 and about 30 minutes of my time in labor.

Disclaimer: I AM NOT A CERTIFIED MB TECH. But I did stay in a Holiday Inn last night!

Jeff

hadam

citruspilot and Racin_fool Thanks for your quick reply.

The Ignition coil is costing me about $90 from stealer. I will go and buy it this afternoon.

I will let you know how does it goes tonight.

One more question for all, which one is cylinder #7, is it the one on passenger side Firewall? or is it next to cylinder #8 driver side?

Racin_fool

#7 is directly infront of #8 on the same side of the engine.

2nd from the back on the drivers side.

hadam

Thanks Racin_fool.

So cylinder on passenger side close to Firewall is cylinder 4?

Here is how this goes then.

Cylinder 4, 3, 2, 1 On passenger side starting from closes to Firewall.

Cylinder 8, 7, 6, 5 On driver side starting from closes to Firewall.

I hope my understanding regards to Cylinder layout is correct. If any one find mistake in my layout, please correct it.

citruspilot

You got it!

Jeff

hadam

Thank you all for your help.

The problem was IGNITION COIL.

I changed all 8 spark plug ($3 each from dealer, why MB use Copper tip). MB P/N A 003 159 67 03

I changed one plug connector [MB calls it “Cable Plug"]. ($13) MB P/N A 000 159 41 42

I changed one ignition coil. ($95) MB P/N A 000 158 72 03

No more CEL, rough idle is gone, Car runs better then before.


Local German Shops wanted $400. [Why in the world these local German shop want to charge you $95 per hour rate, this is horrible, the reason you go to local shop so you can save, but you really don’t save too much with them.

Stealer wanted $650.

DIY cost me $140 plus 4 hours of my time.

DIY your self is PRICELESS.

VonderHaarAMG

I got a cylidner 8 misfire code yesterday. Plugs are all new. I popped off the airbox to look at the ignition coil, and it looks fairly easy to get off. So my question is, how hard to replace is it? My mechanic wants a 1/2 hour labor to do it (about 40 bucks labor). So, anybody have any idea how easy this coil changeout is?

Thanks,
VH

5-Salt

I have same issue but forget exactly how to pull the codes for diagnos'ing the issue - can any point me to a tutorial or advise as to how?

THX!!

Musikmann

You pull codes with an OB2 scanner plugged into the connector to the left of the steering column. In the lower dash you will see a small door hiding it. Post back once you have the code(s). If you don't have a scanner a lot of car parts stores will read them for free.

5-Salt

Have scanner. Will pull codes and advise - thank's for the help!!