Mercedes-Benz Forum banner

1 - 12 of 12 Posts

·
Registered
2002 Mercedes C240 Elegance
Joined
·
155 Posts
Discussion Starter #1 (Edited)
Hey guys,

Before I go on I just wanted to thank everyone for your time and advice in these forums, every post saves users alot of money from your knowledge and experience so thank you.

As for my car, I have a 1986 Mercedes 300e in beautiful condition, when I get a chance I will post some pics and you won't believe that its the origional body. I've done alot to this car and I will name what has been done in the past year so you can knock it off the list.

  • Fuel filter
  • Spark Plugs
  • Starter
  • Distributor Rotor/Cap
  • Air Filter
  • Oil change (every 3000)
  • Transmission Flush
  • Alternator
  • Full Brake joob
As for the the non-related things I named, I know it has nothing to do with the car hestitating but I thought I'd mention it anyway. Now for the problems I will number them because there are unrelated issues here.

My first problem: The car is hesitating from a full stop or red light. No matter how much I floor the car or give it gas for the first 3-5 seconds, the RPM drops and does not accelerate fast, its very slow. After 5 seconds, it kicks in and the car runs like its brand new (at higher speeds or regular 50km/h+). Its just horrible when it starts off for the first 0-5 seconds, and can not even accelerate normally.

Second problem: The car is horrible to start in the winter! Anytime its cold outside (-3 or less), I have to let it sit for about 5 minutes. It is always VERY difficult to start on cold mornings and when it is running, if I give it too much gas it will stall. I have to press the gas very lightly to let it warm up. Once it begins to warm up its fine, but that takes 5min+. I'm guessing the fuel is not going through the COLD VALVE?

Third problem: The car is overcooling, it will not go over 1/4 unless its at a stop and even then it just hits a 1/4 or JUST over. I've owned many 300e's and I know they normally stay at half or just below at normal operating tempature. (I'm guessing this is the theromstat being stuck open) but thats just a guess.

I would appriciate any input from people who know the 300e very well, it could be many things and I want to narrow it down and have a full tune up done. Thank you in advance for all your time. I know 300's slightly but not as well as some of you. PLEASE give me your input if you think you know the problem.

p.s. I've searched a bit and here is what I've come up with for the three problems.

  • OVP relay
  • 02 sensor
  • Engine Coolant Temperature (ECT) sensor B11/2.
  • EHA Adjustment
  • EHR Valve
  • ENGINE TEMP SENSOR
 

·
W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
Joined
·
12,756 Posts
Marco,

Thanks for your questions. Use the search feature of the forum and look for "air/fuel ratio adjustment" Read all the threads and determine if what you read matches your problem. I suspect the car moves on smartly once you can get past 1500-1800 rpm.

If you would, take a few minutes and complete your profile. All of us, including most importantly you, will benefit.

Welcome,

Jayare
 

·
Registered
2002 Mercedes C240 Elegance
Joined
·
155 Posts
Discussion Starter #3
Completed the profile, I'm going to get a paid membership for this site, the information is just great!

I've researched the air/fuel mixture, I believe it may be one of the few problems that I'm having. Thanks for the reply :)
 

·
W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
Joined
·
12,756 Posts
Need help with this, I drive far each day and its getting worse :(
Marco,

What is your DIY skill level? What is the extent of your tools? Do you have a multi-meter with a duty cycle feature? The air/fuel adjustment and all related components of system are very clearly discussed in the search links I suggested yesterday. For the moment, get a long handle 3mm allen wrench and turn the air/fuel adjuster CCW about 1/3 of a turn. If that adjustment doesn't improve things, turn the adjuster about another 1/4 turn.

Jayare
 

·
Registered
2002 Mercedes C240 Elegance
Joined
·
155 Posts
Discussion Starter #6
Hey,

Thanks again for the reply, I will try this and let you know. My DIY skill is pretty high as I've worked on cars for quite some time. I have a great set of tools and an advanced multimeter.

I will made the adjustment settings as you stated and let you know if the car starts running better. I believe this will help the hestitating issues but not the overcooling and coldstart but we must tackle one at a time. My next update will be the results of this adjustment!
 

·
W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
Joined
·
12,756 Posts
If your meter has a duty cycle feature, put the pos pin in the #2 socket of the X-11 connector (round connector with cap behind the ABS pump) and the neg pin in the #3 socket. With the car fully warmed up, check the readings. I suspect you'll find a high number fluxuating around. You want that number to be 50% or a bit less 47-50%.

The CCW turn leans out the mixture. By design, the car runs rich when cold and leans out as it warms up. That is if the engine temp sensor and O2 sensor are working correctly. As for your car running cool, the likely suspect is the thermostat. Get a new one.

Jayare
 

·
Registered
2002 Mercedes C240 Elegance
Joined
·
155 Posts
Discussion Starter #8 (Edited)
Okay thanks alot to the forum and Jayare's help I was able to solve this but I do need some further input. Problem three was solved due to replacing the thermostat. The first and second problem are from the OVP and here is where I am confused.

Every morning the car runs like crap (when the car is very cold it sounds like its running on 1 cylender), AS soon as I give the OVP area a hit or move it slightly, the OVP starts working perfectly and the car runs like it did when it was brand new.

Does this mean the connection itself to the OVP is bad or has a bad ground? Is there a way to test the connection of the OVP fuse itself? I should replace the OVP anyway if its old. I think trying to resoder it and rewire would be a nightmare and could cause further issues. When this OVP is working properly, EVERYTHING about the car seems to run perfect...

Most mechanics have not even heard of a OVP as its only on a few older Mercedes, I can't imagine what some people have paid due to mechanics misdiagnosing this car. Please let me know what you think I should do. I dont want to mess up the OVP connection or wires by resodering it.

Thanks.
 

·
Registered
1994 E320, 1993 300E
Joined
·
364 Posts
Replace the OVP if it is old. It can cause all kinds of problems and are known as failing with age.
 

·
Registered
W124
Joined
·
5,175 Posts
Replace the OVP as has been mentioned because you don't want to mess with it if you have to drive the car a distance every day. But don't throw out the original. Take it apart and look for cold solder joints. The fact that you can change the running characteristics is a great indication you don't have a serious problem with the OVP.

Another thing to consider is that the fuel injection needs to see some temperature to run well. If the thermostat is/was open, it might be contributing to your issues.

Good luck.
 

·
Registered
american 1986 300E 3.0l
Joined
·
107 Posts
yes i agree just go and buy an OVP if it works great and no change then keep it in your glove box just incase. if you read up on it, it does alot and if it goes then u have one in the glove box.(i do)
if i can recall the price(over $100 under $200 cdn) at the dealership
 
1 - 12 of 12 Posts
Top