Misfire - Spark Plugs - Ignition Wires puzzle
10-04-2018, 11:26 AM
#1
Member
Thread Starter
Misfire - Spark Plugs - Ignition Wires puzzle
I've decided to keep the car and fix it as my budget allows. My biggest headache is finding a reputable mechanic in the area, but I already posted another thread about help with that.
This post is about a misfire.
A month ago I replaced all 16 sparks plugs on my E430, 10 days ago and while replacing the rear catalytics, the muffler shop used a CenTech diagnostic tool and found codes P0300 and P0302, which indicate "Cylinder 2 Misfire Detected". The muffler shop also had a mechanic and when I asked him about how to fix this misfire, his first words were "let's replace all the spark plugs". I said thanks and ran away from there, since I had just replaced all spark plugs and knew this muffler guy was trying to pass himself as a real mechanic.
By the way, while standing at lights, the car's RPM is not stable and feels faulty. My first mechanic had told that the engine mounts need to be replaced, and I have that on my list, but engine mounts will not cause the engine to sputter.
I took it to a second shop, 1 of 2 Authorized Mercedes Mechanics in the Bronx. This second shop is recommending that we "start by replacing all ignition wires". What bugs me is that they didn't even look at the wires before saying so. The car has 148K miles and I'm sure these ignition wire have never been replaced. Is it common that these wires give out and need replacement?
This post is about a misfire.
A month ago I replaced all 16 sparks plugs on my E430, 10 days ago and while replacing the rear catalytics, the muffler shop used a CenTech diagnostic tool and found codes P0300 and P0302, which indicate "Cylinder 2 Misfire Detected". The muffler shop also had a mechanic and when I asked him about how to fix this misfire, his first words were "let's replace all the spark plugs". I said thanks and ran away from there, since I had just replaced all spark plugs and knew this muffler guy was trying to pass himself as a real mechanic.
By the way, while standing at lights, the car's RPM is not stable and feels faulty. My first mechanic had told that the engine mounts need to be replaced, and I have that on my list, but engine mounts will not cause the engine to sputter.
I took it to a second shop, 1 of 2 Authorized Mercedes Mechanics in the Bronx. This second shop is recommending that we "start by replacing all ignition wires". What bugs me is that they didn't even look at the wires before saying so. The car has 148K miles and I'm sure these ignition wire have never been replaced. Is it common that these wires give out and need replacement?
10-04-2018, 07:16 PM
#3
MBWorld Fanatic!
On rear cat's - note you had them replaced - so that you know if "blockage" was the reason the rear were replaced - frankly the OE rears could have been cut out - shaken empty - overnite soaked in 50/50 dishwasher detergent and water - blow dried - and reinstalled - no replacement for technical reasons - but can replace for "sound" or "look".
Let clarify symptoms - what you experience - and not pay attention to the codes for a moment
1. If at a braked stop - as the engine RPM starts dropping to idle - if the engine seems to drop below idle like it's going to "choke" - then catches itself before stall and goes back up a bit past idle - then drops back down.. cycle repeats - then this type of "stumbling" or "choke/surging" is generally associated MAF. A genuine Bosch #0280217810 from ONLY a reputable internet seller like Amazon or Autohausaz will be $125-$135 - do a fresh Mann or Hengst air filter for another $14 to boot. With 148K miles - cleaning the MAF won't help - at 148K it is common for original MAF to be off enought on spec to cause "choking"
2. If "missing" - and you suspect spark plugs wires for that cylinder - then the sections coil-to-plug for that cylinder (2) plugs are either "shorter" Bosch 0356912948 - or longer 245mm long/ 9 1/2" Bosch 0356912954 - most commonly one of each - then there are ignition coils.
Switch wires and/or coils with a cyclinder on the other side and see if the "miss"/codes change to that cylinder - I would hate to spend $150 for a wire set and a couple hours labor and find wires are NOT the problem - and if wires/coils to that cylinder are the problem you can order replacement wires/coils for that specific cyclinder.
3. OE Sachs/Lemfoerder engine mounts #2289901 are like $50 each - plus labor - are well worth it when you can get there - if for no other reason as it will cut down the vibration that has been hustling thru the exhaust system - that accelerates break down of the front cats - which in turn block up rear cats
Let clarify symptoms - what you experience - and not pay attention to the codes for a moment
1. If at a braked stop - as the engine RPM starts dropping to idle - if the engine seems to drop below idle like it's going to "choke" - then catches itself before stall and goes back up a bit past idle - then drops back down.. cycle repeats - then this type of "stumbling" or "choke/surging" is generally associated MAF. A genuine Bosch #0280217810 from ONLY a reputable internet seller like Amazon or Autohausaz will be $125-$135 - do a fresh Mann or Hengst air filter for another $14 to boot. With 148K miles - cleaning the MAF won't help - at 148K it is common for original MAF to be off enought on spec to cause "choking"
2. If "missing" - and you suspect spark plugs wires for that cylinder - then the sections coil-to-plug for that cylinder (2) plugs are either "shorter" Bosch 0356912948 - or longer 245mm long/ 9 1/2" Bosch 0356912954 - most commonly one of each - then there are ignition coils.
Switch wires and/or coils with a cyclinder on the other side and see if the "miss"/codes change to that cylinder - I would hate to spend $150 for a wire set and a couple hours labor and find wires are NOT the problem - and if wires/coils to that cylinder are the problem you can order replacement wires/coils for that specific cyclinder.
3. OE Sachs/Lemfoerder engine mounts #2289901 are like $50 each - plus labor - are well worth it when you can get there - if for no other reason as it will cut down the vibration that has been hustling thru the exhaust system - that accelerates break down of the front cats - which in turn block up rear cats
10-05-2018, 09:56 AM
#4
Member
Thread Starter
1. If at a braked stop - as the engine RPM starts dropping to idle - if the engine seems to drop below idle like it's going to "choke" - then catches itself before stall and goes back up a bit past idle - then drops back down.. cycle repeats - then this type of "stumbling" or "choke/surging" is generally associated MAF. A genuine Bosch #0280217810 from ONLY a reputable internet seller like Amazon or Autohausaz will be $125-$135 - do a fresh Mann or Hengst air filter for another $14 to boot. With 148K miles - cleaning the MAF won't help - at 148K it is common for original MAF to be off enought on spec to cause "choking"
I'm going to have a mechanic try the idea of swapping the wires from one cylinder to another to see if that diagnoses the problem. I also don't want to spend a full set of wires, if only a couple of them are bad.
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CarlitoE430 (10-05-2018)
10-08-2018, 08:58 PM
#7
Member
Thread Starter
It was the pair of ignition wires for that cylinder. Paid $50 for that plus a full diagnosis with me under the car being shown all the parts that need to be replaced.
