Hi Guys,

My 04 E320 developed a little shake in idle at 66K miles so I decided to do the spark plugs. Went to Autozone, Advance Auto, and O'Riely looking for the OEM Bosh plats but all these places listed Bosch +2 as the OEM replacement. I replaced all 12 very carefully last week and car became smooth as silk.

since then, I have developed a strane problem. Once in an odd while, I will start the car and drive for lunch or a small chore (maybe 2-4 miles) park the car and 10 minutes later it will crank repeatedly for 10-15 seconds but not start. On two-three tries or so it starts. If it takes second try, no issues - but over two tries, it throws th MIL "Check Engine" light with no stored codes but a I/M message of "Misfire".

I have taken the cover off and inpected for lose plug wires. found one on pass side that seemed not to have clicked. Driver side is very tight so I am having hard time confirming that wires clicked right (I have medium size hands but there is really no space in there.

I did check the harness on each coil on pass side and they were good and tight, But then I accidentally hit the trans dip stick cover dropping it in engine bay and got distracted trying to recover it

any ideas? Someone else I was talking to said are you sure +2 are ok in this car - I dunno - thats what all these auto stores showed. There is no gap adjustment on those either. Please help!

When you put in el cheapo plugs, what do you expect?

Put in plugs recommended by Mercedes.

If you'd like to do a little research, peruse the UK and German websites and see if you can find the plugs you've purchased. You'll discover these are USA only and are nothing but KMart specials.

These are recomended by mercedes! At $4.80 a piece times 12 plugs - not cheap either.

Ok. apart from bashing Bosch+2/+4 - are you stating that these plugs are causing misfire because they are Kmart specials?

I called two local MB Dealer(s) and they both confirmed that Bosch Platinum+2 is an approved replacement plug for 3.2L engine.

I am not trying to start a word war here - jsut seeking a solution. On that note I did replace both air filters at the same time as plugs!

[QUOTE=mobinakhtar;3674674]I called two local MB Dealer(s) and they both confirmed that Bosch Platinum+2 is an approved replacement plug for 3.2L engine.

QUOTE]

Check the owners manual for replacment plug.

Bosch F8DPP332. I used Bosch 7422 which is OEM

Bosch +2 is a big open area. Does the Bosch part number MATCH the owners manual. Doesn't matter where you bought or paid or dealer states. It only counts if it works in the engine.

So lets go with real part numbers. What Bosch part number did you use. Bosch +2 is only the type not the part number.

Actually quite cheap compared to MSRP of OEM Mercedes boxed plugs......

Also how did you "yank" off the cables, if you did not use the correct tools you may have damaged one or more of them-----now those are DEFINITELY not cheap.....

Good question I forgot to ask. For my e500 I rotated the caps then used the 17MM wrench to slowly raise them up. Also you must really push hard to reseat the cap on the new plug. It is easy to leave them up and have a air gap for the spark to jump just to get to the plug. This might cause misfire and ignition system failure.

I have run into a nasty aftermath now. Today Car randomly died at a stop light but started afetr 2nd try in the morning.

On the way back from office, died again at a stop light 15 mins from work and would not start again for anything - just cranked and cranked. I tried relentlessly giving 3-5 mins between cranks for 15 minutes then pushed it into a gas station.

I called the tow service, but their ETA was two hours. 45 mins later, i tried again and it started on first try and ran fine until I got home (17 miles in city traffic).

New Course of Action: I am removing all coils again, all cables, reinstalling them with two caveats:

1) I will check resistance on all cables to ensure they are not damaged.
2) I will not overtighten the coils - on another post over-tightening coils caused misfires (dunno why)

I used a 17mm ranch and an "L" plier to "pop" the wires off the plug and then carefully removed them. No apparent damage to wires but who knows (Ohmmeter will tell).

Will update once finished. Apparently several other MB enthusiast have used Bosch+2 with no issues. I am pretty sure my problem is cable related as I did not hear the "POP" sound on any but couple plugs when pushing the cables back on spark plugs.

Wish I can get the idea on what bloody cylinder is getting misfire. My car had no code stored - but an I/M information "misfire" per my OBD-II scanner. It says "1-fault no stored codes. I/M - Misfire"

This time "Check Engine" came back - I will try to take it to autozone to see if their scanner will read the stored code. getting frustrated at my OBD-II canbus scanner too - thinking maybe its the scanner not being able to read the code.

Any ideas appreciated!

Ok. There could be multiple problems here. First thing's first. When you replaced the spark plugs, did you replace the plug surpressor ends/plug wires??? I have run into it time and time again in the dealership, where plugs have been done and the culprit ended up being wires. Usually we recommend doing them as a pair to avoid this issue. Checking the resistance of the wires is a good first step. One other thing to check is the metal shielding ends on the wires. This is the part that goes over the plug. When you look at them, there should be no signs of discoloration, corrosion or traces of water that has vaporized (white chalky film on the outside). If you do find any of this, I would recommend replacement. However, you can try to clean them with a "clean" wire brush. The reason for this is simple. The metal ends on the plug wires actually contact the spark plug at the hexed portion to create a ground for the ignition system. If this contact surface is dirty, you will have intermittant misfires. Second, the fault codes that you had read out at Autozone should have been whats known as a P-O code. Should have been like a P0300 or a P0301. They are as follows:
P0300: random misfire
P0301: misfire cylinder 1
P0302: misfire cylinder 2
etc........
The cylinders are arranged with 1-2-3-4 on the passenger side of the car from the front and 5-6-7-8 on the driver side from the front on a V8. The V6 is the same only 1-2-3 and 4-5-6. Also, if the misfire was bad enough for a long enough time, you may have to reset the flywheel adaptations. The engine control module will learn the way the engine is running and become accustomed to it. If you change the plugs and fix the misfire, the engine may still try to run as it did before. At least that's what Mercedes Technical tells us all of the time.
Now, to the other problem I mentioned. The stalling out is most likely not even due to the plugs. 9 time out of 10, if a vehicle comes into the shop for a stalling issue that will not restart right away. And usually restarts after the vehicle sits for 15+ minutes. The problem is almost always the crankshaft position sensor. As the car warms up the resistance in the sensor changes and eventually goes open causing no reading from the sensor to the engine module. Which in turn causes the vehicle to stall. Oh, and 97% of the time, never sets a code or check engine light. I hope all of this helps.....

I took the car to an indy - and guess what - he thinks its the CPS, and nothing to do with spark plugs. specially as the car does not start but if we wait 20-30 mins it starts right up with no misfires. Maybe thats why there are no misfire codes. There is only I/m information and no stored codes.

Thats a pretty common problem on the 113 and 112 engines. I would definately start with the crank position sensor, especially if you have to wait awhile before you can start it again. We see them all of the time at the dealership... Good luck..

Thanks Rizzy. A neighbor friend of mine has the same car and at 13K miles it got flooded (sucked water via air ducts) and destroyed a piston + rod so he swapped complete engines (he got lucky ad found one with 15K miles) couple years back.

He still has his old engine sitting in the garage. I am going to swap his old engine's CPS for mine tonight.

Part is so cheap - $35plus shipping from ebay/ $50-60 internet/$112 dealer - but this one is available NOW and for FREE!

Two questions:

1) Will this swap automatically clear the MIL or should I reset it?
2) Do I need to reindex? If yes, does anyone know the procedure to re-index (I did search but mostly found "index finger" LOL.

thanks,

MOby

Probably won't clear the codes but if it starts and runs that is a good indicator. The pickup is basically coil and if yours is failing it can do exactly what you are experiencing. IF you make the change it won't take long to see if it solves the problem. If it does solve the problem then clearing the code is a smaller issue to not running.

The Check engine light will have to be cleared. As far as the crank sensor indexing. There is no indexing of the sensor. It's pretty much a plug n' play set up. It's recommended by Mercedes Benz to have the Flywheel Adaptation data cleared. This will be done automatically over time though. Your vehicle will recognize a change in the running characteristics and start to adapt, though this way is slower. As long as your car didn't have a violent shake/vibration due to misfires before, you should be OK. Oh, and when you take the bolt out, be very careful not to drop it. It's a special reverse torx so it can clear the sensor body. You can stick some dum-dum, sticky puddy, or even but not recommended, chewed gum in the end of the socket so the bolt sticks to it and does not fall into the abyss. Going back in, I usually lay a piece of paper over the socket and then press the bolt head through the paper into the socket. The paper takes up the gaps and holds the bolt. Hope this helps......

Great advice Rizzy. I already had it replaced by my buddy yesterday - He is very much experienced and did exactly what you suggested - placed a paper to not lose the bolt. I had some oil on the sensor (a thin film) which is very, very odd. I know my pan-cover leaks a bit but not enough to reach "that" part.

So far so good - it has not cut out on me yet. probably in a few days running - I will know for sure.

thanks every one for their kind replies and help.

The oil on the sensor is most likely due to a rear crank seal leak. Pretty common on the 112 & 113 series engines. Glad to hear its running good.