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Discussion Starter · #1 · (Edited)
Hi
I need help please..
I have w140 s500 v8 1995. I have a perfect start and run when my car cold and when it go to normal temperature or after 10 mnts from the drive my car loss of power and have more fuel consumption.
What's the problem?? 馃様馃様
Thanks for help 馃檪
 

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'99 S420 122K
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There could be several issues to be explored.

What is the mileage?
Has any recent service been performed?
Have any CODES been pulled?

Off hand I'd suspect a malfunctioning O2 sensor, a bad MAF sensor, or a temperature sensor sending bad inputs to the computer telling the MAF to enrich the fuel mixture.
 

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Discussion Starter · #6 ·
There could be several issues to be explored.

What is the mileage?
Has any recent service been performed?
Have any CODES been pulled?

Off hand I'd suspect a malfunctioning O2 sensor, a bad MAF sensor, or a temperature sensor sending bad inputs to the computer telling the MAF to enrich the fuel mixture.
There could be several issues to be explored.

What is the mileage?
Has any recent service been performed?
Have any CODES been pulled?

Off hand I'd suspect a malfunctioning O2 sensor, a bad MAF sensor, or a temperature sensor sending bad inputs to the computer telling the MAF to enrich the fuel mixture.
My car have 165,000 km
I replaced the ecu, engine coolant temperature sensor, Air filter, fuel filter, plugs, all of this new. And no fault codes right now馃槖馃槖
 

Premium Member
'99 S420 122K
Joined
1,611 Posts
My car have 165,000 km
I replaced the ecu, engine coolant temperature sensor, Air filter, fuel filter, plugs, all of this new. And no fault codes right now馃槖馃槖
Many Mercedes vehicles built from '93-'97 suffer from eco-wiring, where the plastic flakes off of the wire and exposes the copper wire. This can cause shorts in the wiring, ALL THE WIRING, not just the wiring harness.

I suggest you retrace your repairs/replacements to inspect the wiring around the areas you were working.

Why did you replace the ECU? Who diagnosed that as needing replacement? Ditto the coolant temp sensor. What symptoms were you observing before replacement?

When replacing the air filter, did you possibly damage any of the air intake plastic hose pieces?

My guess is that something is altering the air/fuel mixture causing your current symptoms and I strongly suspect a temp sensor telling the ECU your engine isn't warming up.
 

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Discussion Starter · #8 ·
Many Mercedes vehicles built from '93-'97 suffer from eco-wiring, where the plastic flakes off of the wire and exposes the copper wire. This can cause shorts in the wiring, ALL THE WIRING, not just the wiring harness.

I suggest you retrace your repairs/replacements to inspect the wiring around the areas you were working.

Why did you replace the ECU? Who diagnosed that as needing replacement? Ditto the coolant temp sensor. What symptoms were you observing before replacement?

When replacing the air filter, did you possibly damage any of the air intake plastic hose pieces?

My guess is that something is altering the air/fuel mixture causing your current symptoms and I strongly suspect a temp sensor telling the ECU your engine isn't warming up.
I was have some problems.
and the mechanical put the car on the computer and the fault codes showed. That's why I replaced the ecu and the engine coolant temperature sensor. What a bout the transmission?
May it cause this problem?
Because the transmission work good when the car cold and I have some slipping between the gears when it go to warm temperatures
 

Premium Member
'99 S420 122K
Joined
1,611 Posts
I was have some problems.
and the mechanical put the car on the computer and the fault codes showed. That's why I replaced the ecu and the engine coolant temperature sensor. What a bout the transmission?
May it cause this problem?
Because the transmission work good when the car cold and I have some slipping between the gears when it go to warm temperatures
Transmission is probably not the culprit, but it sounds like it is need of some attention, also.
 
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