1997 E320, suddenly looses acceleration - PeachParts Mercedes-Benz Forum

Bigdaddybenz · #1 02-12-2008, 07:02 PM

This happened twice......Driving along, suddenly gas pedal does not accelerate the engine when applied, tach stays at idle, engine runs smooth, no check engine light, car coast to a stop.....

Pull over, restart engine and vehicle accelerates correctly as if something was "rebooted"

This happened twice today, I suspect that it will get worst, please any advice would be greatly appreciated!

Thanks, in advance!

Arthur Dalton · #2 02-12-2008, 07:52 PM

Car is going into Limp mode ...have it scanned for codes

Also, does it do it right after brake application?

Bigdaddybenz · #3 02-12-2008, 08:53 PM

Scanned for CAN codes?????............I would think that limp mode would cause the check engine light to come on.......I experienced the infamous misfire problem because of a defective spark plug connector last year and the engine management system apparently cut off the fuel injector in an attempt to save the converter.......I was under the impression that this was considered "limp mode" as I was still able to operate the vehicle in a diminished capacity.

I am certainly not questioning your advice, I simply wish to better understand the concept.

Bigdaddybenz · #4 02-12-2008, 08:59 PM

ps, no check engine light activated during this episode........Check engine lamp works as it briefly turns on (tests) during the normal engine start up procedure.

Arthur Dalton · #5 02-12-2008, 11:56 PM

A limp activation can come from traction system , EA , or CC fault and that is why I asked about the brake.

So, again, did you notice the problem after using the brake pedal????????

Is yes , then change the infamous brake lamp switch.

Bigdaddybenz · #6 02-13-2008, 04:21 PM

Actually, this happens during my commute at highway speeds between 50-70 mph, without brake application.....Had several episodes of this today in the 40 mph range without touching the brake pedal........If I were to describe the "feel" of the gas pedal when this happens, I would say that it feels "airy" and it is completely unresponsive, no matter how many times I step on the gas pedal, the engine remains at idle speed and will not throttle up!.....If you look at the tach, it remains in the 800 rpm (idle range) as aI coast to a stop, at which point I remove the key and restart the engine then proceed to drive as if nothing happened at all until the next episode.....

If this were not a Mercedes, I would best equate this to a broken throttle cable that somehow repairs itself once I restart the car.......ps, at no time does the engine stumble or misfire during these episodes, it jus simply drops down to idle speed, remains SMOOTH running and will not respond to the gas pedal being depressed.

You mentioned "limp mode" earlier, but wouldn't limp mode allow you to move the vehicle, to some degree????? When this happens, my car just coasts and will not accelerate at all......Just for the sake of diagnostics, I pulled over, put the tranny in park then shifted into gear, I could feel the trans kick in but when attempting to accelerate I get ZERO response and the car will not move..................Once I restart it, BAM! Everything's normal.........Today the frequency of episodes is increasing and I'm clocking them by miles, it is occuring about every 20 miles driven, or so.

Hope the helps, please reply and thanks for th email!~