98 c280 - 59k limp mode? Trans issue
 

Hey guys,

Trying to help a friend out with a car.

98 c280 with 59k - he just bought it it was the "theoretical" old lady's car - not a mark in the leather, nothing.

So at part throttle it drives pretty much perfectly at least at in town speeds.

When you bury the throttle, it bogs and revs to 4 grand and sits there, like it doesnt want to shift or it's in the wrong gear... You can barely get the car to 60 it feels like you have to fight the trans.

Car idles perfectly, and has NOT thrown a CEL yet....

Drives perfect at part throttle. Just will NOT accelerate at speed.

Any and all ideas would be appreciated.

Thanks,

George

Try washing the air mass sensor with special air mass cleaner.
Has the fuel filter been replaced?
Does the car have original spark plugs?

It sounds like the MAF sensor is reporting too little air. This is the most common failure scenario, IMHO. This causes the fuel mixture to be too lean at WOT/heavy acceleration.

So even though there were no codes -

I swapped the MAF and the car is like a brand new car.

Thanks guys!!

Take care,

George

It would've started throwing fuel trim codes once the engine management ECU reached it's limit to correct the fuel mixture.

I guess what threw me for a loop was the fact that it fell on its face when you gave it gas and just sat there - wouldn't rev past 4k, and went nowhere.

That's what got me thinking trans or limp mode. I never thought the MAF being incorrect would stop it from revving. I just figured it would throw the lean codes as you described, as the car wouldn't be able to provide enough fuel via the trims to keep the 02's happy. That didn't happen, the car just straight would not go.

Take care and thanks again,

George