c280 sport 1994 idling problems

[tariqm]

Hi I am a new member and need some help please. Have a c280 automatic which tries to cut out when idling at junctions / traffic lights. Seems OK when the car is cold but when it warms up then it has this problem Also, when I rev the engine in neutral / park, the revs drop before increasing. Have tried changing Air Flow Mass sensor (not a genuine merc part though) and this has not made any difference.

Any help would be appreciated

 

[bigasotonuk]

Hi
I,m no expert but have you thought about replacing the throttle body

 

[tariqm]

is it cheap / easy to do?

 

[bigasotonuk]

hi
not sure on price easy to do look on euro car parts web site

 

[C220GJS]

Before you think about changing the throttle body try cleaning the butterfly valve and throat of the throttle as they can get gummed up with the oily fumes from the cambox breather.
The throttle body is a very expensive item and would normally be reconditioned by someone like BBA electronics.http://www.bba-reman.com/
George.

 

[tariqm]

Thanks for the tips. Will try and let you know how I get on

 

[kid-jensen]

Sounds like a sticky Idle controller to me.

Certainly worth cleaning it out with Carb Cleaner (the Comma stuff is good and aggressive--that's what you need). May be better to take it off to make a thorough job.

If no improvement, and you're pretty sure that's the problem, get one from an online scrappy.

A work-around would be to wind-up the mechanical stop (if it has one) if not, tighten-up the throttle cable outer).

It won't be a proper fix if there's somethinng else wrong, but it may get you out of trouble.

 

[tariqm]

The car has also had a distinct lack of power ever since I have had it - would have expecting a lot more punch from a 2.8 litre. Does this point to a different problem or can it be associated to any of the above?

 

[Stevie A]

According to Haynes check for vacuum leak at throttle body area as this will cause lack of engine power and stalls. So too would a clogged fuel filter. When was the fuel filter changed? If you don't know, get it changed and change spark plugs too asap. These items will cost only a few pounds, try this before worrying about more expensive stuff as it is usually simple stuff that causes trouble and simple stuff gets overlooked.

Idle control valve can be problem according to what I've read but that does not explain the lack of power.

 

[television]

Wanting to cut out and hesitating before picking up shows that you have a weak fuel mix. Why not get the codes read out, the EGR valve could be stuck open,the lambada could be giving false info.
It could be expensive running in circles.

Malcolm

 

[C220GJS]

The idle speed actuator and throttle valve are part of the same unit.

 

[Stevie A]

So could be idle control valve as George has pointed out correctly as I don't know much about this area.

 

[kth286]

first step should be to get the codes read by a Merc specialist, not anybody else.

 

[tariqm]

i've changed the spark plugs and ht ignition leads and also the MAF. Problem now is that if I rev very slowly from standing position the revs drop to almost zero before I get a surge. If I accelerate hard then the problem is not so bad. Could it possibly be the fuel filter? I've not changed it in the four years I have had it (done 50k miles in that time). Any advice will be very appreciated

 

[Stevie A]

Get the fuel filter changed, it's only £10. You'll be burning your fuel pump out if the fuel filter isn't changed.

 

[television]

i've changed the spark plugs and ht ignition leads and also the MAF. Problem now is that if I rev very slowly from standing position the revs drop to almost zero before I get a surge. If I accelerate hard then the problem is not so bad. Could it possibly be the fuel filter? I've not changed it in the four years I have had it (done 50k miles in that time). Any advice will be very appreciated

Hardly likely to be the filter as the car uses more petrol running at 50mph then it does at idle.

Malcolm

 

[Stevie A]

Hardly likely to be the filter as the car uses more petrol running at 50mph then it does at idle.

Malcolm

It's only £10 for the fuel filter Malcolm and is something that should have been changed and could arguably, according to Haynes, cause symptoms mentioned.

 

[television]

It's only £10 for the fuel filter Malcolm and is something that should have been changed and could arguably, according to Haynes, cause symptoms mentioned.

I agree with you,always left too long and over looked.

Malcolm

 

[eric242340]

You say the MAF was changed, but was it re-programmed with DAS? If not it will give the wrong signals to the ECU. This coding/programming can only be done with Mercedes Benz Star diagnostics. And 100 percent you must change the fuel filter. Also, with the engine running, pull the vacuum pipe of the fuel regulator - any fuel leak from the regulator - then change the regulator, its not expensive.

 

[tariqm]

Changed all the filters but no difference. Is programming MAF essential? I changed the MAF (not merc original) but it made it slightly worse so I have reverted to original MAF. I thought as long as ignition was off when MAF is changed then it shoudl be OK? Also tried running car with MAF totally disconnected. This way the idling is OK but it doesn'trun very well - backfires when under heavy load