ZorroAMG

Hey all,

My 1990 300E has been quite goofy for some time and I am compiling this thread so that I can get all my thoughts out and fix it. Some of you have replaced some or all of these parts and I'd love your feedback/advice

Symptoms:

- Hesitation/sputtering/shaking acceleration until higher rpms
- Hard shaking at idle, does so in park and neutral as well

I did a tune up last year (plugs, new cap, rotor etc) problem still persists.

Diagnosis:

I have searched all the threads on here and mercedesshop etc. and this is what I've come up with for parts to replace. May just do em all eventually over the next few months anyway seeing as my car has 100k Miles approx.

- Idle Control Valve - Bought one off ebay. Any help as to WHERE it is and how to replace it? Do I need to get the shop to do it? Also I read that we should replace the tubes as well. Thoughts? Source?

- O2 Sensor - Got a bosch unit in stock at a supplier for $210. Can any shop/mechanic do this? Part number? Better source?

- OVP relay - I've seen "newer" 2 red fuse units before and I wanted to source that one if it's the one to go with. Source? Part Number? How hard is it to replace?

- EHA Valve - Holy crap, these can be expensive. $1000 for a re-man one...found one on e-bay for 219'ish. Thoughts? Is this necessary? Part Number?

- Fuel Pump Relay - Part number and source?

Is this what it looks like:

or this?


What's an MAS? Same as MAF?

- MAF - Mass air flow sensor? Source? Part number?

- Fuel and Air Filter - I have no idea how long it's been for fuel filter, I have a K&N in the air cleaner that I've never oiled or anything since I put it in back in 2002. Should I put a new one in?


I realize this can all be found by searching and I have searched (hence knowing what parts to start with) but I thought some of you that have recently done these R&R's may have part numbers and sources handy.

Any OTHER possibilities for my issues? Fuel related? Fuel pumps etc?...

STLe320

I believe MAS and MAF are the same thing...but I can't guarantee that.

ZorroAMG

Yeah, I've been seeing the two words interchanged too...

Also, called the parts place I use and they couldn't find an MAF listed for the M103, does this engine have one?

roach_juts

i have the same problem to , the cars idle's goes up & down, i think i think the fuel filter is 1 of the problem .... on my opinion

Saijin_Naib

AFAIK, the MAS like the second picture is what my m104 uses, not sure if it applies to the m103.

berti_00

yeah idel up and down for me was the fuel filter... i changed mine and it was soooo sooo dirty dang.......

change your spark plugs again, they are not much but very helpful

ZorroAMG

Source for a good fuel filter? Should I get a new K&N or just replace with an OEM one?

ZorroAMG

So my car has an MAS, like the one pictured above, not the MAF?

What does the fuel pump relay look like and location?

neanderthal

also look into your spark plug wires for the erratic running. the inline 6 is a smooth running engine at higher speeds and can easily hide a misfire.

and engine mounts for the rough idle/ hard shaking.

STLe320

I had the OEM filter and later switched to a K&N. Granted, it didn't really give me anymore horsepower, but a felt a little difference when I got into it and it kicked down. It also (somehow) helped with my rough idle.

In my opinion, I'd just try little hit and miss things like that and see what happens. Maybe new plugs/wires and a new OEM or K&N. Oh, and check your engine mounts just to see if that could be a culprit of your rough idle.

Bigpete123

Mark, make sure you do those things 1 at a time. No sense in buying all of those parts if you don't have to.

The Idle Control Valve is under your air filter assembly. Simply remove it and you'll see it in plain view. You may need to change the hoses, but look yourself first. If they are flexible like they should be, I doubt it's the problem.

The ICV is very easy to swap out yourself.

And like Saijin said: M103's don't us an MAS Control Unit. And be glad yours doesn't... I had to replace my MAS Control Unit and it was not cheap for that little thing. It houses the fuel pump relay and also does all kinds of other crap. All I wanted to change is the fuel pump relay but I had to buy the whole damn thing.

By the way, your symptoms are identical to symptoms i've had for 4 years. I have spent thousands on thousands taking my car to highly qualified mechanics who can't seem to sort it out.

It's an elusive problem for me. I've changed all of the parts you list above and many more. It seems like every time we swap out the spark plugs, the problem goes away for about 300 miles and then comes right back.

I have given up. The problem has not gotten worse but it hasn't gotten better. I will drive my car until it needs another major repair ($1,000 or more) and send it to the scrap yard or sell it for peanuts... it's only worth $3k and I'm tired of the heartache!!!

Anyway, lol, good luck to you. I'm sure you'll have more success that I've had.

ZorroAMG

Are engine mounts expensive to replace? Labor intensive?

ZorroAMG

Yeah, BigPeterOneTwoThree,

I will do them one by one. I ordered the ICV so I'll do that and a K&N and fuel filter first. What is that picture above that I posted that has M103 on it and MAS written on it?

As far as selling it etc, I know our cars aren't worth much, monetarily, but I love the way mine looks and drives and will only replace it with a C63 at LEAST. That has to wait as I am going back to school in Jan and all my free cash is tied up in various developments.

Thanks for the help guys!

PS where is the fuel filter located?

New dual red fuse OVP? source?

neanderthal

fuel filter should be just aft of the passenger rear wheel (right rear) where the fuel pumps are located. small, cylindrical object inline with fuel piping, and IIRC it comes before the fuel pumps if you are tracing the piping from the back to the front.
ie fuel goes from tank > filter > pumps.

you can do it yourself. but be prepared to have gas all over you.
i believe its just hose clamps that you need to undo, so a screwdriver should be all you need, although i would recommend having at least two vice grips to pinch the fuel lines and ergo minimise spillage. a fire extinguisher should be on hand, just in case.

ZorroAMG

^^LOL....looks like that's a job for Mr. Mechanic.

Thanks for the help! Got any answers for my other questions? New OVP source/part number, fuel filter source and part number?

Appreciate it!

Oh I forgot to mention, over the last year the car had a bad battery and I left lights on a couple of times, requiring a jump. That would be bad for the OVP, correct?

190E 16V

Mark, sorry to hear about your beloved.

I have K&N air filter, too.
Yes, you need to do something with it.
Whatever else you do, this is long overdue. You will need to buy a kit with cleaner fluid and fresh oil - about $20-$30, I think.

Might not be cheaper to buy a paper element each time, but you will not be washing petrochemicals down the drain each time you rinse the filter out, either. Something to think about.

Also, I would suggest sparkplugs, but I understand that it is very critical to get the exact ones and NOT deviate from the tried and true.

Best of luck

190

ZorroAMG

Thanks dude....will get a new K&N I think. Cleaning it is a PITA from what I've heard.

ZorroAMG

Ok, so after reading Zedstyle's thread on his start/idle issues, I found a source to buy the following brand new items:

Fuel Pump Relay - $27
OVP Relay - $62
O2 Sensor $122 ($45 for ford retrofit model)

Thoughts?

ps2cho

Head over to Autohouse Arizona. They have the best prices compared to ANYWHERE.

Engine mounts are pretty easy assuming you have a jack. Disconnect Exhaust at manifold then just put a thick piece of wood under the engine block, jack up high enough -- One bolt on each mount and out they come.

I would IMO leave mounts seeing as you know performance issues are showing. Call around some local mechanics (doesn't have to be benz exactly...european is fine) and see if they can smoke test the car. This is so you can rule off a number of vacuum related issues.

Trust me. If I had done my vacuum smoke test in the beginning it would have saved me a lot of cleaning up, mess, time and the most important, money.

battlecat714

those prices seems reasonable. Still need those part numbers?

ZorroAMG

No, thanks battlecat, I ordered those items already.

ps2cho, thanks for the tips, I will ask for a smoke test once I swap out the OVP and O2 sensors.

X03

I have a fuel pump sitting at home if you want it for cheap, its the same one you have in your 1st picture. It has a different part # though (002 545 13 05). Thought I needed to replace mine but in the end never used it...

ZorroAMG

Fuel pump relay or fuel pump?

2PHAST

If at idle your car shakes, but it goes away when your driving, then that would be a problem with the motor mounts and it would be time to change.

The MAF is a mass airflow sensor, later model M104's had them, the M103 did not.

Your K&N should be taken out, cleaned and then re-oiled. Not a complicated process, you spray the cleaner on the filter as per the directions, wait 10 minutes or so, then rinse it out. When it dries, you re-oil the outside of the filter very lightly and your good.

If at acceleration your car lacks power or it seems like it is running on less than 6 cylinders, be sure to check your distributor cap and rotor, these can cause this type of problem as well.

X03

Its the fuel pump relay.

If my cars idle in D is lower than normal (550) and shakes a lot - does this show a problem with my motor mount? When I pop it into neutral or drive it runs normal with no shakes...