1988 190e 2.3 idle stall OVP?
 

I have a 1988 190e 2.3

for the last 3 or 4 years i have been replacing the OVP every 6 months or so. The car runs great for 6 months, then starts to stall occasionally, the stalling begins to happen at idle or if I am pulling up to a stop light, but gradually gets worse. After another month or so of this it will begin stalling at highway speeds. I pop in a new OVP and it runs perfect for another 6 months.

I was trying to find out the cause of this and thought that maybe the fuel pump relay was causing the OVP to wear out prematuerly. So i ordered a OVP and FPR and installed them both. The car was running fine before i installed the new parts except for the stalling. After i put in the new OVP and FPR it was a little harder to start and stalls all the time at idle now. I pulled out the new FPR and left in the new OVP. It seems a bit better but still idles very low and stalls now and then.

I have studied the posts here religiously but cannot solve this problem. SInce I do not have diagnostic equipment or know how, I tend to pull parts and replace to see if that solves the problem. Would someone please share thier thoughts or similar experiences here? I love this car. This is a great site.

Hello Machnumber2,

I have the same problem with my 260E, 1988, 370 000 km.
I opened ( very carefully) the pump relay and the OVP ( both original from 1988) and found some broken weldings of electronic components.

I welded them, and replaced both FPR and OVP in the car.
Seems to work, but the probelm is so erratic , that I can't say if it has been soved.

Let me know what are your findings if you do the same.

Sometimes it makes the problem stop but then its back again right away, something must be causing the ovp and over parts to fail early is my guess

In examining ours, I found the failure is due to improper assembly line procedures - a very common situation in electronic fab, unfortunately. The practice is, solder the connection, then trim the excess lead. What happens is that the trimming equipment unavoidably puts a high shear force on the connection, breaking the alloyed metal. A hairline cylindrical fracture results, and the poor contact and arcing that occurs deteriorates the contact until it no longer functions.

Often these fractures are invisible, or nearly so. Oxidation of the metal may not make a simple solder reflow a good solution. The solder should be removed, and new flux used in remaking the connection. If there is no contact between the parts being soldered, that should be corrected at this time.

Steve

Thx for the info

try adjusting the CO mixture.
a low sensor plate position causes fuel starvation at idle

my car had similar problem before and was repaired by an MB tech.

read my post.