1992 190E 2.6, Very hard starting cold
 

I am working on a 1992 190E 2.6 75,000 miles. The car is very, very difficult to start cold and runs poorly until it warms up. It obviously is starved for fuel during cold starts, since it fires right up with a little starting fluid. It runs and drives fine after the engine warms up.

The thermo sensor switch on the head seems to be ok, but the cold start valve has been checked and is functional, but it is not being energized during cold starts.

The electronic control boxes and relays are behind the battery. I do not see a fuel pump relay as most others. There is a "MAS" box, a over voltage relay and two large control boxes ( one for the ABS and the other the main engine ECU I suspect).

It seems like whatever controls warm up running and cold starts on this version is the culprit. Can someone point me in the right direction. I hate to replace expensive ECUs or relays if not needed!
__________________

CHeck fuel pressure
test coolant temp sensor
starting device(cold start valve)

check the fuse in the ovp or the ovp itself.what you have described is a car trying to start in limp mode.

Is ABS lamp ON ??

Fixed!

You guys are great. Yes Arthur the ABS light was on and now it is off. David, I went out and re-checked the fuse on the OV relay it was still OK. I replaced the relay with a good used and the car started up cold and ran just fine! Maybe you can explain to me why the ABS light was on Arthur if you get a chance.

Thanks again. Let me if you need any help on any pre 1975 MB (my specialty).

ja17@att.net

The ABS light is a common indication that the OVP is causing problems. It was on when I bought both of my w124's, and a new OVP fixed both.

Thanks ps2cho!

JA,
ABS Module is same OVP power feed as MAS/ECU ...so , a quick test is to look for ABS lamp default, indicating OVP feed problem. Knowing this is the same feed, the Tech is simply using the ABS lamp default as a power glitch/interruption detector tool. So, if one sees a post responce asking "ABS lamp ON ? " , OVP diagnosis is where we are heading.......
The orig OVP was a Siemens and they were a problem , so the replacement was a redesign.
Very Common on models thru 95 w/IL-6.
The chassis you are working on will still run manual/less electric controls /closed-loop w/bad OVP , but if you get any later HFM /SFI -full electronic ones ,[ 93-95] they will not b/c they are fully computized engine management dependent.

So, an ABS lamp coupled with a start/run complaint on either system [ 103/104] is a quick tip-off that first suspect is a faulty OVP relay.....so common a fail rate that we keep a " TEST OVP " in the tool box for a time saving swap test instead of DMM tracing.
If you have no test relay available, sometimes a few relay taps will indicate the relay also...but not always.

PS ..I see the TTS problem was resolved @113. He left a nicely written responce........

Thanks Arthur,

I reallyappreciate it!

You're Welcome..............

1991 Mercedes 300TE 4matic Hard Start
 

I am currently experiencing the same issue almost exactly but my ABS light is not on. Would you still think the OVP relay is a good place to start?

Yes.

It's good to see Arthur posting again regularly.

I can't seem to find this part for my 190E 2.6. I replaced 1 blown fuse and now the car idles correctly, when it was dying. Still hard starting. Like it not getting fuel. When it does finally start it idles just fine.

190 E cold start OV relay hard start
 

Hi; Im working on a 190 E gas . I read A reply about OV relay and replaced it On the first start the ABS light went out and car started and ran great engine temp was at 38 degrees F. I drove it for a few miles and it ran great! After letting it sit out in the cold for 4 hours I cranked it only to have ABS and no start. Is there anything that can take out the new relay? the battery had 12.5 volts . Bad relay? short some were? Thanks in advance for your help
Bobby