Erratic idle, cold start, 190e

[johntom]

Hi
i've just bought a '91 190e 2.0, auto, petrol (68k, totally original, in fact near mint). The car seems to turn over for a few seconds before starting from cold (although it starts straight away when warm) it then runs fine, however when warm the tickover is erratic between 500 & 1000rpm? Help?

 

[Stevie A]

OVP relay being faulty causes hard starting and erratic idle. If ABS light has been coming on sometimes then more than likely OVP relay.

 

[television]

Make sure that your OVR is putting out the full 12v on pins 87.
As Stevie A says a common fault after a number of years, often bad soldering but also suffer from decay.

Malcolm

 

[johntom]

Hi
would the ovp relay cause erratic idle when warm? ps i haven't seen the abs light come on.
thanks Johntom

 

[television]

Hi
would the ovp relay cause erratic idle when warm? ps i haven't seen the abs light come on.
thanks Johntom

Yes it can cause that, and a voltage test would confirm, tapping the relay during test for a stable 12v out

Malcolm