stephanielamb

Our 1987 300E has been having little problems that seem to have gotten worse now that it's "cold" out (70 in the morning instead of 95). We've had the car since July, and it's only noticeable under the hood problem is a small transmission fluid leak (isn't this everybody's car though?)

When it was warm outside, every once in awhile I would have engine troubles in the morning. It turns over okay (but does take a few seconds) and idles just fine. However, when you push down the accelerator you can ear it occasionally missing. If you put the car in drive, it jerks around a little when you hear the engine missing. I used to be able to just give it a little more gas and it would overcome this and go 'zooooom!' (hope I'm driving in a straight line) but the sub-100 temperatures don't seem to help.

Now, it's doing this not only in the morning, but also when I start the car after work. As soon as the engine temp gets to 80 C, it's fine! My best solution thus far has been to rev the engine in park and drive around slowly in a parking lot before actually going anywhere.

Yet another symptom - last week this happened twice. One morning I had driven it around a little..not quite enough to get up to temp.. stopped at a light. When I gave it gas to get going again, the car shuddered a little, made the same noises, and killed the engine. I started it again and it happened again. On the 3rd try or so I got going, with no further problems. This also happened at lunchtime later that week!

I'm not looking for an exact diagnosis, but it would be great to hear if people have had similar problems and whatnot, so I can decide if we need to take it to the reputable mechanic across the street asap or if I need to try and get it to the Benz mechanic across town whenever he's got time.

Further information about the car:
200somek miles
Had tune up/spark plugs/wires done in May or June (just before we got it)
Transmission leaks a little
Added fuel injector cleaner last week, hasn't helped yet (and we ONLY use premium gas)

Am I missing something?
Thanks!

shadowgriffen

Re-check your sparkplugs, pull one out at a time.

Same thing was happening to me, I figured since I had just finished giving my car a tune up the spark plugs were out of the question.

Well turned out spark plug on cyl #3 was toast

replaced and voila! no more spuspuspusputterring!

stephanielamb

I thought i'd give a little update on this, the problem has been more complicated than we expected!

The stuttering when cold kept getting a little worse at a time, so we finally took it to the shop. Guy pulled the spark plugs first thing, and they were all black. He told us the fuel was way too rich, adjusted the mixture, and installed new Bosch plugs/wires. When we got the car back, it idled great! No more misfires! I drove off around the corner and.. stutttt-t-t-t-t-ter.

It's like you're going in slow motion when it does it, I feel like I could push the car faster even though i'm giving it gas.

Anyway, we took it back to the shop after that, where the guy did some more distribution adjustments, and wow! Now i've never heard it idle so great haha. I drove for quite awhile that day without problems, then it did it once when I was making a turn after sitting at a stoplight.

It's been a week since that trip to the shop, and every day it seems to be a little more 'eh.' When we first got it back, we were sure it was driving better, only stuttering maybe once per trip when it was cold. However, we also noticed that it may or may not stutter when accelerating from a dead stop when the engine is warm!

Today was probably the worst. It was cold-ish and rainy outside. At one point I was stopped at a light and when I got to turn the car actually stalled! I thought I couldn't believe it at the time, but a few hours later (on a cold engine) it did it again at a light, in traffic, and I probably made a lot of people mad. :P

It DOES seem to start again just fine. And once the engine is warm it almost always goes just fine!

I'm running out of ideas here.. I'll probably take it back to the shop but i'm afraid of getting into a big hole replacing part after part and getting nowhere.

Does this sound like a telltale sign off anything? MAF sensor? Fuel filter? OVP? (The mysterious part that seems to break that I know nothing about..)

Oh, and the car definitely doesn't misfire now!

Thanks!

YNVDIZW124

Search the forum, this has been covered but check your cold start valve and OVP relay. It's red with a clear cap and has a 10A fuse that's red too behing the computer.

Also maybe the temp sensor and i always say this because once i changed mine my car has been running really nice...

shdoug

I don't think the OVP has the same issue it does on the newer M104 engines. Yours is the M103 engine with Bosch K-Jetronic CIS fuel injection. It sounds to me like possibly a flaky temp sensor if it only does it sporadically when cold. It also sounds like your mechanic is guessing as well, but he's definitely made some improvements so I wouldn't give up on him yet.

YNVDIZW124

I can comfirm the OVP does go bad on the m103 engine because there are two versions of between 1986-93 and mines has blown fuses and goes bad with moisture.

It can maybe be a bad cold start valve that's colgged or leaking...

Also, remember the temp sensor is the one at the rear of the engine not the green middle on. That's just a temp sensor for you a/c and the dash...

stephanielamb

Thought i'd finally update! Between a dead hard drive and craziness at work, it's been a month since i've been here..

I was stupid and took it to the same stupid shop again.. they kept finding nothing, and nothing, and then finally a corroded connection on the cold start valve, which they replaced. (luckily only a $10 part). When I picked up the car they told me it still had a little trouble starting but NO stutters whatsoever..so I drove away and...stutter stutter. :p

And to think, if we had taken the car back there their next idea was to replace the entire fuel distributor!

Luckily, found a good shop to go to (Myerstar in the Phoenix area for those interested). Took it in yesterday, picked it up today!

Turned out to be a bad coil. Not anything I ever thought about? Haven't driven it fully cold yet but seemed to run like a charm when I picked it up!

danholm

Thanks for the update.

hineywineries

I'm not sure you are out of the woods yet. A defective coil is a slim shot on these models. If that did fix the problem, congrats, but if not, you might look at the distributor cap, the temp sensor, and the EZL module. Also you said the plugs were black which may indicate that you are running in open loop. I hope the mechanic didn't over correct the mixture in the lean direction. You can get a good quality DVM, remove the pass floor mat, disconnect the signal wire to the 02 sensor, and monitor the voltage. With the engine at operating temp readjust the mixture to swing at about .6 volts. Good luck.

stephanielamb

Thanks, i'll keep that in mind, but so far it seems to be running flawlessly.