idle drops when in gear

[mr rosher]

hi guys, and girls, i own a 1993 e280 auto, and over the last year or so, i`ve had the problem of idleling, when in p - n idles 750 - 800 rpm, as soon as you put her in D - R the idle drops to 550 - 600 rpm and she starts to judder as if its going to cut out, today i was told by a work colleague that on autos theres an electrical switch that when you go from P-N TO D-R the switch increases the rpm, is this true, and if so where is it ??. on the gear box, or in the engine bay, any help would be appreciated as this may be the problem,

 

[television]

Cars up to 1990 had an idle relay that increased the idle by 50 RPM, the same goes for air con, and this did the same.

I believe that the relay was under the dash on the earlier version, but your is electronic, try cleaning all of the relay and control unit pins in the link

http://www.detali.ru/cat/oem_mb2.as...2433&VIN=*&CT=F&cat=44R&SID=54&SGR=075&SGN=04

 

[mr rosher]

ok malcolm, i'll try this in the morning and let you know how i get on, the relay on the left of the o.v.p.r, could this be the idle relay

 

[television]

ok malcolm, i'll try this in the morning and let you know how i get on, the relay on the left of the o.v.p.r, could this be the idle relay

I am lost on the cars from 1990-1995 as they use the Engine ECU to control most of this, Its a blank for me, I would love to help

 

[mr rosher]

Cars up to 1990 had an idle relay that increased the idle by 50 RPM, the same goes for air con, and this did the same.

I believe that the relay was under the dash on the earlier version, but your is electronic, try cleaning all of the relay and control unit pins in the link

http://www.detali.ru/cat/oem_mb2.as...2433&VIN=*&CT=F&cat=44R&SID=54&SGR=075&SGN=04

hi malcolm tried what you said, cleaned all the relays but still idles slightly under the 600 rpm when in drive, which causes her to judder slightly and when you start to accelerate theres a small flat spot, which i guess would be the cause of the low idle,