Power loss at "take off" ('95 S320) - PeachParts Mercedes-Benz Forum

sab · #1 07-08-2003, 07:30 PM

I have an unpleasant condition, where my S320 has no power at "take off" from e.g. a traffic light. Once I completely depress the throttle (WOT) it has full power.
The car runs completely normal when it is cold. Once it is warmed up, especially when I shut it off and then back on, it starts to have an intermittend surging idle and this pesty power loss.
When I got a read out from the check engine light a while ago it indicated the O2 sensor, I changed both O2 sensors and the condition persists.
I reset the check engine light after changing the O2 sensors and the light came back on.
What could this be? MAF sensor? Vacuum leak?
I tlooked for vacuum leaks, but could not find one.
Where can I get the codes read out from my check engine light? Or should I buy the tool?
Thanks,
Sab.

suginami · #2 07-08-2003, 10:37 PM

I would suspect either a vacum leak, Mass Air Meter, or Throttle Actuator.

If I was a gambling man (and I'm not), I'd put my money on the throttle actuator.

sab · #3 07-08-2003, 11:59 PM

How do I check the throttle actuator?

Would that set off an error code?

And just a clarification to the idle problem, it intermittently bounces between 600 and 1000 rpms.
Thanks,
Sab.

suginami · #4 07-09-2003, 12:04 AM

If you get your car scanned, it might have codes stored.

One way to check your throttle actuator is to swap it out for a new one, but it's not very cost effective as it's about a $1,000 part. :-(

One sign that your throttle actuator is going out is a failing or intermittent cruise control. The throttle actuator is also called EA/CC/ISC module (electronic accelerator / cruise control / idle speed control). All three functions are combined in one part.

Your problem could just as likely be a vacum leak or a Mass Air Meter.

I would take your car to an independent mechanic that specializes in Mercedes.

sab · #5 07-11-2003, 10:56 AM

Just before I have to bite the bullet and bring it to the dealer.
Chances are not very favorable in South Florida that I will get honest service. From my expirience I would say about 300 to 1 that I will get ripped of again or get the part installed faulty at a high labor rate. YMMV

The car also has a strange symptom, where the engine does only rev to 4000 if in neutral.
In gear it will go to the actual redline with good power.
Does that sound like the mass airflow sensor?
How much is the tool to read the error codes and where can I get it?
Thanks,
Sab.

Arthur Dalton · #6 07-11-2003, 11:29 AM

4K rev limit in N/P is Normal.
Torque Converter safety limiter...