300E conking out at idle - PeachParts Mercedes-Benz Forum

JordaanDMC-12 · #1 06-27-2014, 01:04 AM

Hey all, been having an issue with my beloved 91 300E

It happened when I was driving to work, everything was normal and had no warning of an issue when suddenly at a stop light, on a busy street she died out completely. I tried restarting and she would crank and try to start up but wouldn't. I had her towed home and assessed the situation the next day. The longer she sat, the longer she would run. If you hold the RPM's up she could run forever, but when shes at idle, she'll start to miss and then conk out.

I had her towed to a indy and they told me it was the fuel pump and wanted 700$ to fix. But it really doesn't feel like a fuel pump issue to me. The pumps aren't making any wonky noise and I don't have a loss of power other than just idle. Today I put fuel system cleaner and fresh gas, drove her around the streets for 45 minutes and had a little "bumps" at idle here and there. But I made a sudden stop and she died out. So i tested it, every time I brake hard or suddenly she dies out

I feel like it's something electrical... Can anyone give me any leads of where to start? Thanks!

Ferdman · #2 06-27-2014, 06:23 AM

When was the Oxygen sensor replaced last? I have experienced similar stalling issues with a faulty/worn out Oxygen sensor.

gatorblue92 · #3 06-27-2014, 06:52 AM

What do I do when my M103 is giving me trouble: A rough guide - Mercedes-Benz Forum

pawoSD · #4 06-27-2014, 09:01 AM

Crank position sensor is bad. Test and replace. With a warm engine it should read about 700-900ohm on a multimeter. If it reads outside this its faulty.

lorainfurniture · #5 06-27-2014, 09:55 AM

When was the last time you gave your car a tune up? Cap rotor wires and plugs? Start with the simple things first

pawoSD · #6 06-27-2014, 09:56 AM

Quote:

Originally Posted by lorainfurniture

When was the last time you gave your car a tune up? Cap rotor wires and plugs? Start with the simple things first

Agreed, M103's need cap/rotor/plug repairs all the time. I think I did it twice on mine in 4 years/40k miles

lorainfurniture · #7 06-27-2014, 02:04 PM

Quote:

Originally Posted by pawoSD

Agreed, M103's need cap/rotor/plug repairs all the time. I think I did it twice on mine in 4 years/40k miles

With genuine wires I was able to get 5 years. Bosch cap and rotor last about 3 or so years, spark plugs every year. Buying quality ignition parts is a must on these cars otherwise they go bad rather quick.

JordaanDMC-12 · #8 06-28-2014, 02:35 PM

Thanks guys for the replies, I took your advice and started with the simple stuff and may have possibly found the problem. I've done maintenance with this car, wires, plugs, fuel filters but somehow I just happened to forget about my distributor cap and rotor

Well I read what you all put and decided to check it out. The same cap and rotor have been on the car since we bought it 5 years ago

and who knows how long it was on before that... Popped it off and this is what I found.. Needless to say i'll be ordering the parts today!

Ferdman · #9 06-29-2014, 06:57 AM

Wow, I have never seen a distributor cap and rotor in such horrible condition. I am eager to hear how the engine runs after installing new Bosch parts.

slk230red · #10 06-29-2014, 09:47 AM

Quote:

Originally Posted by lorainfurniture

When was the last time you gave your car a tune up? Cap rotor wires and plugs? Start with the simple things first

Yep....start with the simple things first! A while back a guy was getting off the interstate and his W201 2.3 died and wouldn't start. He was going to check the fuel pump, relay, etc. I told him to check the plugs, wires, distributor cap, and rotor. Here is a picture of what he found when he removed the distributor cap.

pawoSD · #11 06-30-2014, 11:01 AM

Wow!! How was that engine even still functioning? That is the worst condition cap/rotor I've ever seen.

rayhennig · #12 06-30-2014, 01:15 PM

Quote:

Originally Posted by pawoSD

Wow!! How was that engine even still functioning? That is the worst condition cap/rotor I've ever seen.

I keep ranting on about "starting with the simple things". And I always rant about the HT systems in these cars and how they must be 1st class with no cheapo parts.

I sometimes think that people have a masochistic streak and they want the problems to be serious and costly. I've fallen into the same trap myself.

Do let us know how it goes after you've installed your pristine new distributor bits!

RayH

johnflight1 · #13 07-01-2014, 02:30 PM

The pictures posted by Jordaan dmc looks more like a mechanical failure, as if something migrated and started rubbing.I would take it apart after installing the new parts after a few miles just to see if the new parts are holding up without damage. There is no reason a cap and rotor should be eating each other up because of contact.

rayhennig · #14 07-01-2014, 03:56 PM

Quote:

Originally Posted by johnflight1

The pictures posted by Jordaan dmc looks more like a mechanical failure, as if something migrated and started rubbing.I would take it apart after installing the new parts after a few miles just to see if the new parts are holding up without damage. There is no reason a cap and rotor should be eating each other up because of contact.

Good thinking. I wonder if the cap and rotor are not matched. It looks as if the top of the rotor has been in contact with the underside of the cap, around the middle contact.

RayH

JordaanDMC-12 · #15 07-01-2014, 11:35 PM

Well, today I got the parts in for my 300E, couldn't wait to get off with work and put them in to see if I could finally drive her again without issue. Got home, opened the box, everything looked good and I went to the install. I had to get the metal post off the old rotor arm since the new one didn't come with it. The three bolts holding it in would just not budge and were stripping, sprayed tons of nuts off and it did nothing.. I tried the manual way with a grip wrench and it only cracked the plastic it's in there so tight. MASSIVE disappointment... The car gods just didn't want me to repair today... Called Mercedes to see if I could order the parts so they could be in tomorrow. I'm told parts just closed at 7... look down and it's 7:02

But I noticed the ceramic? plate that lies against the metal backing has a crack in it.. Not sure if this will affect the performance, but something inside me tells me to just get a new one just to be safe... Should I or is this something that wouldn't affect anything? Please see pictures below.. Hoping to have her going by Thursday