Cold start and low idle problem

[jacjam]

I have a '93 190E. Recently the battery was connected to the wrong terminals in the dark by a helpful friend! As a result the ABS light remained constantly on and the car struggles to start when cold. When it does start it only just idles (at 500rpm)

A local garage suggested it was a relay that had blown and replaced it, this resulted in the ABS light no longer being constantly on, but did not rectify the starting problem.

The garage has subsequently replaced the idle valve and is now stumped as to what the cold start problem is. They are suggesting that it maybe the O2 sensor.

Any help/ideas would be greatly appreciated.

 

[sunil sood]

it sounds like your overvoltage protection relay was at fault-there are two fuses on the relay-were these changed by the garage?

 

[cmonyousaddlers]

W126 280SE

Similar problems on my 83 280SE. Having searched the archive material, seems to point to cold start valve or this overload protection relay. Finding the cold start valve is easy. Where the h*ll is the overload protection relay on a 126 to check these fuses?

 

[jacjam]

I have checked the two fuses on the OVP Relay, both are 10A and seem to be OK, I wondered if the Relay itself could be faulty even though it is a new one.

I was told by the garage that the emissions are way higher than what they should be and the car does feel really "sluggish" when driving.

 

[Andy]

Hi

Your initial problem was the overload protection relay. Now you need to find out whether it blew the KE ECU. I would get it into a MB specialist or stealership. I doubt its the oxygen sensor. Its more than likely as a result of the initial connection of the battery leads incorrectly. I doubt the vehicle is more sluggish I think that is more phychological.

Otherwise you will be changing all sorts of stuff and it will cost you more dearly than if you get it looked at by someone who knows.

Regards

Andy@ www.mercedesservicing.com

 

[jacjam]

Thanks Andy, I will give this info to the garage and hopefully that will sort it, if it is the KE ECU, how would you check this and if it needs to be replaced what is the cost involved ?

Thanks.

 

[jacjam]

Blown ECU ?

Further to your info, I asked the MB specialist to check the ECU, I can't seem to get a straight answer from them as to whether they have done this, I don't think so. They claim to have solved the problem by adjusting the Air slide valve. Rubbish. The car still idles at 500rpm in Park/Neutral when cold. The car seems to lose power when driving (on overrun, not under acceleration). Idle when warm is a little lumpy (bearing in mind they claim to have fitted a brand new idle valve). I am very frustrated by this, I am convinced it is an electrical problem as a result of the battery being incorrectly connected for a few seconds.

The car has done 112000 miles and has a full service history, in every other respect it is fine, apart from a slight whine at speed from the rear of the car. It also seems to idle about the right speed ca.750 rpm when hot.