1995 S420 Help Please!! - PeachParts Mercedes-Benz Forum

basafa · #1 10-29-2006, 01:26 AM

I own a 95 S420 for 7 years. About 2 years ago the car sat in the garage for about 5 weeks, when I tried to start the car, it would not start. I charged the battery, the car started but ran rough. When I stopped the car it would not restart. If it sits for a while ( 30 min ), it will restart normal. Surprisingly the check engine light is not on. I took the car to an independent shop they scoped the car and it showed problems with the cruise control actuator, but he was not sure that this was the problem. The car sat till last week. After purchasing a new battery I took the car to another shop. The mechanic tried to restart the car but it would backfired and failed to start. His diagnosis was that the throttle body actuator was bad and the distributor caps and rotors also should be changed. He suggested to also replace the camshaft position sensor. I checked with MBZ dealer and the throttle body actuator is also referred to as cruise control actuator or E-Gas actuator. I have read in the forums that there is a problem with wiring harness in these Mercedes models. How would I know if the problem is the Cruise Control Actuator or the Wiring Harness? Is there diagnostic tools that gives more information than others? Your suggestions and advice are most appreciated.

Thank you in advance,

Minnet · #2 10-29-2006, 05:08 PM

I don't believe in throttle body actuator.

The throttle is operated by a computer following situations:

In idle to control idle speed
In cruise mode to control vehicle speed

If you have electronic accellerator and antislip, it will also control the throttle in normal driving mode instead of a mechanical link.

In any case the actuator will simply act as throttle control, whereas your problem more sounds like an ignition or mixture problem.

I once had similar symtoms, where it would run without problems for long time. But in certain temperature/humidity conditions it would stumble and stop being very hard to start again, and then driving perfectly alright for another period of time. That turned out to be the ignition coil.

But a manifold vacuum leak could also create your symptoms, so try first to look for any leaks.

whunter · #3 10-29-2006, 05:19 PM

Quote:

Originally Posted by basafa

I own a 95 S420 for 7 years.
2 years ago the car sat in the garage for about 5 weeks, when I tried to start the car, it would not start.
I charged the battery, the car started but ran rough.
When I stopped the car it would not restart.
If it sits for a while ( 30 min ), it will restart normal.
Surprisingly the check engine light is not on.
I took the car to an independent shop they scoped the car and it showed problems with the cruise control actuator, but he was not sure that this was the problem.
The car sat till last week. After purchasing a new battery I took the car to another shop.
The mechanic tried to restart the car but it would backfired and failed to start.
His diagnosis was that the throttle body actuator was bad and the distributor caps and rotors also should be changed. He suggested to also replace the camshaft position sensor.
I checked with MBZ dealer and the throttle body actuator is also referred to as cruise control actuator or E-Gas actuator.
I have read in the forums that there is a problem with wiring harness in these Mercedes models.
How would I know if the problem is the Cruise Control Actuator or the Wiring Harness?
Is there diagnostic tools that gives more information than others?
Your suggestions and advice are most appreciated.
Thank you in advance,

Where are you?
Nearest major city.

Drain the fuel, and refill with fresh fuel.
Bleed the bad fuel from the lines.
Try starting.

Evaluating Electronic Engine Controls
http://www.peachparts.com/Wikka/EngineControls

This Volvo club page has a good overview of K-Jetronic Fuel Injection
http://www.volvoclub.org.uk/tech/fuel_injection/k_jetronic.shtml

You need to be aware of this issue on your car.

MB Wiring Harness Failure
http://www.peachparts.com/shopforum/general-information/128181-mb-wiring-harness-failure.html#post927185

Have a great day.

basafa · #4 10-30-2006, 02:07 AM

Thank you Minnet & Whunter for your replies.
I live in San Carlos (Northern California) about 30 miles south of San Francisco. Unfortunately, I’m not mechanically inclined. Trying to learn what is the best way to get my S420 repaired. Minnet, in your reply you are stating that you don’t believe in Throttle body actuator do you mean that it can not be the cause of the problem or that the throttle body actuator and cruise control (e-gas) actuator are not the same parts. When I drove the car to the shop last week, as I stopped at signal lights. To move on, I had to give gas gradually so the car wouldn’t die. Once it got going the major hesitation would go away. Please advice me, as what I should do next. How would I know if the mechanics diagnoses is correct.
Thanks again for your help.

Qamar · #5 10-30-2006, 05:06 AM

Use any good fuel injector cleaner in your full fuel tank and run the car on 160Km for about 5 minutes or so. Hope all will sttle down. This what my mechanic did on my car. I have 95 E320 and was having more or less the same problem which you are having at the moment.

Hope this helps and keep us posted

whunter · #6 10-30-2006, 03:12 PM

Quote:

Originally Posted by basafa

Thank you Minnet & Whunter for your replies.
I live in San Carlos (Northern California) about 30 miles south of San Francisco. Unfortunately, I’m not mechanically inclined. Trying to learn what is the best way to get my S420 repaired. Minnet, in your reply you are stating that you don’t believe in Throttle body actuator do you mean that it can not be the cause of the problem or that the throttle body actuator and cruise control (e-gas) actuator are not the same parts. When I drove the car to the shop last week, as I stopped at signal lights. To move on, I had to give gas gradually so the car wouldn’t die. Once it got going the major hesitation would go away. Please advice me, as what I should do next. How would I know if the mechanics diagnoses is correct.
Thanks again for your help.

There are some good MB repair shops near you.
ShopForum > General Discussion > Good MB Shops
California
http://www.peachparts.com/shopforum/california/

Minnet · #7 10-31-2006, 05:42 AM

Quote:

Originally Posted by basafa

[FONT=Times New Roman][SIZE=3] Minnet, in your reply you are stating that you don’t believe in Throttle body actuator do you mean that it can not be the cause of the problem or that the throttle body actuator and cruise control (e-gas) actuator are not the same parts.

What I say is, that the throttle actuator is used for many purposes: Idle speed, Cruise speed, E-gas etc, and that it does the same thing as you do with a mechanically linked accellerator: Opens the throttle.

The throttle does apparently move, but the engine does not respond correctly to its movement. So the problem is probably not in the throttle actuator but in other parts of the engine control.

I would rather look at ignition system or mixture control.

Or as the other replies suggest, it could be impurities in the fuel, clogged fuel filter etc.

mioba · #8 10-31-2006, 06:45 AM

when you recharged the battery did you spary it, was it still connected to the car,

if so you caused a malfunction in the ecu, you can reset this by removing the fuse, and reinserting after about 5 mins.

pcmaher · #9 10-31-2006, 08:28 AM

You need to have a good mechanic pull any stored fault codes from the car. It is very difficult to diagnose these cars without knowing what fault codes might be present. Keep in mind though that many items in this car are tied into each other. The failure of one part can create false fault codes. The ETA (Electronic Throttle Actuator) could be bad. Wiring insulation failure is a wide-spread problem. In addition, there are potentiometers inside the ETA's that wear out with time. That will also cause all sorts of problems. These links may help...

http://v12uberalles.com/throttle_actuator_rewire.htm
http://pages.prodigy.net/jforgione/MB_asr.html

basafa · #10 12-14-2006, 02:44 AM

Thanks to all for great advice. The mystery problem was the engine wiring harness.
As repeatedly mentioned by many, this is a common problem for this type of vehicle. In addition, I ended up doing a major tune up including replacing distributor caps, rotors and fuel injection cleaner.
All is left now is to purchase 4 new tires and the car is good to go.(for now)
Let’s see what goes wrong next? Hopefully nothing!

Thanks again.