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Billy
Billy, Trainer/Master tech.
Category: Mercedes
Satisfied Customers: 3498
Experience:  Trainer 8+ years, Master tech. 10+ years, SAE member
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Mercedes-Benz C280 98 c280; goes into limp-home mode during

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'98 c280; goes into 'limp-home' mode during normal driving. (I assume it's limp-home, because full throttle will only achieve very light acceleration and has excessive peddle play) After reseting the throttle it works normaly, for a while, but eventually the throttle becomes almost inoperative.
simptums are:
Extremely timid acceleration
No passing gear
No 'Check-Engine" light
Will (eventually) reach full RPM and shifts normally or manualy
Any ideas? I'm desperate! I really hate this "feature". Someday it'll get me killed when I step on the gas and nothing happens.

Billy :

Hello and thank you for using Just answer! I'm Billy and i will assist you with this. Feel free to ask if further info is needed.

Billy :

I would appreciate some further info on the matter:

Billy :

- please confirm that check engine light or no other warning lights are on..........and that check engine light does turn on with ignition and then off

Billy :

- how are you resetting the throttle?

Billy :

- did you check anything yet?

Customer:

No 'Check-Engine' light.

Billy :

- how are you resetting the throttle?

Billy :

Given the info i already have, i can tell you the following:

Billy :

- if check engine light is operational (turning on for a second, with ignition on, and then off all the time), then you are not experiencing the limp home mode......

Billy :

You have a lack of power, which could be caused by a number of factors, but in my opinion, it is a faulty throttle actuator motor.

Customer:

check engine light comes when ignition is turn to 'On', goes off on start-up.

Billy :

You should have the throttle actuator inspected, and if possible, connect the vehicle to a scan tool, and read the live data while driving the vehicle, and this should show the faulty component.

Customer:

resetting throttle: turn ignition to 'on' wait 5 secs, press peddel to floor, turn ign off, wait 5 min, restart

Billy :

ok

Billy :

Again, you are not experiencing limp home mode.............but you are having reduced performance, due to a faulty component......

Billy :

I would first suspect the throttle actuator motor, as it is a common issue on your model, and it would cause the same symptoms..........however, i think you should have a scan hooked, read the live data, to figure out what sensors are reading etc...to get to the faulty item.....

Customer:

That makes sense, I'll follow up on having it scanned and focusing on the throttle actuator.

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