cold start valve vs. ovp
 

I have read many threads about the same thing. And now its hapening to my 89 300e.
Low idle.
Stalls at lights.
Rough cold start
abs light on.
At first I was told that it could be the cold start valve and a few threads confirmed that that could be the issue. Now however I have seen some poastings that say it could be the ovp relay. This seams like it also be a likley problem ass well. Oh and the abs light is on.
I love my car and I want to fix her myself. However I dont have the money or time to fix phantom problems. And judging by some of the posts that I have read I dont want to trust a mcanic to fix my problems. or at least try fail and charge.
Hey you guyes colectivly know a hell of a lot more than me so any help would be much appreciated.:D

There are some bulletins on this issue and I can tell you that most likely that you have 2 seperate problems. OVP can be tested with readily available tools. I can send you the document.

sweet!
 

Ok thanks for the reply if you want you can e-mail the doc to me jke3e@yahoo.com
I dont know though I kinda hope its the ovp.

for the stalling/Cold start:

1. no speed signal from the speedometer to the cise control unit
2.crankshaft postion sensor
3. EZL ignition system
4.electrical connections at ignition coil
5. Sockets of OVP and fuel pump relay bad solder connections
6. cise control unit
7. A/C compressor control unit
8. cold start valve
9. loose connections(grounds, cise wiring harness
10. Internal fuel leakage

had a similar problem on a 190E 2.6 and it turned out to be an internal fuel leakage problem. You may also have malfunction cise components

Wow thanks man I apreciate the help. of the problems that you listed which would be simplest to fix? Im thinking like easy to hard you know?:D

The easiest things to check are checking the OVP ,fuel pump relay, fuel hoses by visually inspecting them. The relays should have no loose sockets and connections. Also check the fuse in the OVP. Check the fuel hoses by looking carefully for cracks etc or gas smell on the hoses or the pumps. Also check the fuel pump cover for drip marks. Thats how I found my leak is by leaking at the cover and saw that they were drip marks that stood out from everything else. Alot spots on the cover light then I saw some dark spots which told me there was a leak there. The next thing would be to test the connections make sure everything is tight and not loose. Clean up ground connections. Then you could test continuity of the cise unit to the componets in the engine compartment by taking a dvom and measuring the resistance of the wires to and from the control unit. The wires should have .3 ohms or less of resistance.

the other things i didnt mention have test programs

thank you
 

Hey I got an early call tomorrow but after work I will be under the hood I will kep you posted on my progress. Thaks a lot!

If the ABS light stays on, check the OVP relay. First, check the fuse on top of the OVP relay. Also, check that the OVP relay is fully seated into the socket. If problem still exists, then you will probably need to replace the relay.

To bench test: Ground on 31 and Battery on 15, relay operates. Then, with battery applied to 30, 12v should appear on pin 87E and 87L.

http://i179.photobucket.com/albums/w.../OVPRelayA.jpg

http://i179.photobucket.com/albums/w...d/OVPRelay.jpg

The OVP supplies power to the ECU and the ABS computer. The car will run badly if the ECU is not on. As said previously, check the fuse on top of the OVP. If it's good, and you can check with an ohmmeter, take the relay out and remove the case. Resolder the connections at the bottom, put the case back on and plug it in. There is no cost for doing this and will save you some money. If this does not work, get a new OVP.

My 95 E320 just started doing the samething. It died a few times at start up, is running like crap, doesn;t have a steady smooth idle, and the abs light comes on. I bought this car as a project and have replaced all of the normal issues with this model except replacing the OVP.

Start with the OVP. It's $65 for a new one on-line, and from reading here: if it isn't bad, it will be. I ordered one for a spare and have had a bad one in one of my diesels, I'm a believer.

The ABS light with the bad running is almost a sure sign.

FWIW, I've been a professoinal MB tech for 12 years and have never replaced a cold start valve on a 103 engine. They just don't go bad.

Then why do they seem to have such a hard time cold starting and idling?? :o (Maybe I am just bitter....)

Just thought I would pass this along, make sure you have spark plugs with a heat range of 145 installed.

Bosch part number bosch H 9 DC or bosch H 9 DCO

"Then why do they seem to have such a hard time cold starting and idling?? (Maybe I am just bitter....) "



The cold start valve is a very simple part of a complex system. There is a reason the newer cars don't have CIS injection. Most manufacturers gave up on it well before Mercedes did.