W210 E200 flat spot at 2500-3000rpm

[nb78]

Have changer the air mass sensor as the car would not start and idle, have also changed the fuel filter, but the car has a hesitant flat spot in all gears at around 2750 - 3250 rpm. Any ideas?

When you add an aftermarket air mass sensor, does anything require reset?

Also have a lesser power battery on the car, I know this sounds stupid, but would this affect anything?

The car is lovely otherwise, it has been off the road for a long while without the battery connected - any ideas?

 

[Parrot of Doom]

How long has it been sat there? Petrol goes off with time.

 

[nb78]

It passed its mot with the new air mass sensor, but this flat spot is really getting me mad. Put the old mass sensor on and it idles like a dog, but if i manage to get it to 3000rpm, there is no flat spot

 

[television]

Sounds a possible EGR valve stuck open ?

Malcolm

 

[nb78]

EGR valve? Is This a simple fix?

 

[television]

http://www.detali.ru/cat/oem_mb2.as...607722.618&CT=M&cat=19Y&SID=14&SGR=090&SGN=03

This valve sits in the exhaust manifold and returns harmful gas back to the intake or inlet at cruising speeds,if stuck open this will cause rough idle.

You can test by taking of the pipe where it joins to the inlet and blank it off to test.

Malcolm

 

[nb78]

Can it be repaired?

The air mass I put on is an aftermarket one off ebay and am a little worried this could be the problem. If I rev the car in neutral there seems to be no real flat spot, but it could have a little hesitation in there. It does not do it all the time, for instance if i really accelerate and change gear in high revs the flat spot is not there.

Do you need to reset the ecu after changing the air mass?

 

[nb78]

The car is a 98 e200 petrol manual, if that helps?

 

[television]

The car is a 98 e200 petrol manual, if that helps?

Thanks it does help. I thought it was a 320.

On the 200 there is no EGR valve that I can find.

Can you unplug the MAF with the electrical plug and try it mad see how it runs.

Was the part number on the one from Ebay the same as yours

malcolm

 

[nb78]

The part number was the same and it passed the emissions test, but this flat spot is there most the time at 2750-3250 rpm, like a judder. I changed the fuel filter today as it sounded like fuel starvation.

The guy i got it off ebay said the ecu required resetting?

 

[television]

The part number was the same and it passed the emissions test, but this flat spot is there most the time at 2750-3250 rpm, like a judder. I changed the fuel filter today as it sounded like fuel starvation.

The guy i got it off ebay said the ecu required resetting?

Most MAF's run them selves in after 50 miles or should I say adapt, I will have a look in the morning to see if it has to be programmed.

malcolm

 

[nb78]

"Have you adjusted idle/reset ecu on ours as it is a factory part"

This was there latest response.

Many thanks for giving me your time on this issue, nick.