After some more digging I came across MB - 004 545 9124/9224 - VDO Nr. 36/2/20 which seems correct - could someone advise pretty please?

 

If the cold start valve made a difference, there ought to be multiple faults.

Cold start valve is meant to be inoperative above approx 15*C and run up to 12sec at temps -20*C with only a few secs at freezing.

Without the CSV, the engine should want to start but fail. The video you posted indicate engine that fires a stroke or two... and would have fired with the starting fluid spray.

 

Thanks Djenka, based on what we've experienced the last two days it did look like the switch was keeping the CSV open longer than it should, thus flooding the engine. After the thermo switch was disconnected the engine fired up after a few attempts, and it ran ok afterwards. Yesterday the switch was reconnected and surprisingly the engine fired up, too. I checked the resistance on the switch and it's actually very close to nominal specs both hot & cold states (approx 0 and 50 ohms below 15°C and 60 & 270 ohms above 15°C). So at this point I'm not sure what to make of it other than the thermo switch got "hung" thinking it was, say, -20*C, and thus spraying the fuel for way longer than it should given the actual temperature. It's a pickle, no doubt about it!

 

You could just umplug the CSV if temp is over the 15°C when you crank... it will make no difference.

My car did have this fault a few times but it miraculously restarted bh itself... except not this time. Permanent fault are easier to find so i do feel lucky the car is home.

 

I hear you Djenka, chances are that something more sinister is going on but for now she runs just fine - hesitation is gone (that might be due to new spark plugs & injectors though) and currently temp. are around 10°C. The car never had issues starting up once warmed up / hot, it was only giving me grief when cold cranking. I think I ought to rename her to Gremlin

Regarding your most recent hiccup, did you get a chance to check both components?

 

Turn the key on push down on the air sensor plate and verify that you hear fuel running through the injectors. If yes the car should start just by pushing down the sensor plate. If it does start like that your sensor plate is probably out of adjustment. Be careful, don't push down the sensor plate more than a few seconds or you will flood the engine and could start a fire.

 

Hi roncallo, thanks for the advice and apologies for the delay in replying. I just followed your guidance and the car doesn't start, note I only pressed the plate for 3 secs as I don't want to see my face on TV news being led away by cops after having burnt down the neighbourhood

At any rate my old girl purrs like a kitty again, for now anyways!

 

Sooo.... My problem is back - the car sat in a garage for a week, and today she's cranking like crazy but won't start when the thermoswitch is connected. So I've let all the fuel evaporate from the intake, then disconnected the thermo switch and took the cold state readings (i.e. below 15C coolant):
- 48.3 Ohms on G pin vs approximately 50 Ohms in the specification
- O Ohms on W pin vs approximately 0 Ohms in the specification.

I left the switch disconnected and after a few cranking attempts she fired up and ran rough for a while, but then stabilized at idle and warmed up ok to approx. 80C. At that point I took the following readings from the thermoswitch:
- 63.5 Ohms on G pin vs approximately 60 Ohms in the specification.
- 270.1 Ohms on W pin vs approximately 270 Ohms in the specification.

At that point I reconnected the switch and the car starts just fine. I've then disconnected the cold start valve and pointed the tip into a bottle, started the car again & let it run for 20 secs - the CSV didn't spray any fuel, so I know it doesn't open when the engine is hot. Also, as part of my research I disconnected the CSV for 24h last week to check if it's leaking, and again there was not a drop in the bottle.

So, the question to all electric gurus - can the few Ohms off in both cold and hot state on the G-pin signify the switch is faulty and cause my cold start problems? The MB manual I use states the specs "approximately", it doesn't clarify that it means, for example, +/- 0.5 Ohm or +/-5 Ohms as shown below. I could really use some guidance here please as I'm running out of hair to pull out

 

Ladies and gents, mystery solved! Or at least I like to believe so, I could be gone crazy at this point.... Here's my findings:

- I measured the coolant temp - 16C, and the resistance of TTS indicated the contacts are closed.
- I removed the TTS to check p/n and I could tell the coolant where the switch is inserted was actually much warmer. Bottomline - the switch shouldn't spray ANY fuel at this point, even if the spec on it reads 15C +/-3C.
- I reinstalled the TTS and disconnected the CSV, pointing it to a bottle. I cranked the car after a few spins she fired up perfect, no hesitation, straight to idle. I checked how much fuel CSV sprayed and as you can see approximately 2-3ml; not much, but I assume it sprays much more fuel as coolant's temp decreases. This also explains why she starts fine every day as long as she ran recently, but will not fire after sitting in a garage for a week - at which point the coolant temp is equal to outside, probably 8-10C, and the CSV stays on for too long given the conditions and floods the engine.
- I then confirmed the CSV doesn't spray once TTS contacts are open, explaining why there's never any issues with hot start.
- Lastly, the alternator is putting out 13.75V so for now I'm leaving at as-is; dash light didn't come on, for now I assume yesterday was a result of messing with bits & pieces. Definitely need to watch out for that in the future.

To summarize, my conclusion is that while TTS works perfect in the higher temp range it doesn't do so at the lower temp spec, energizing the CSV for longer than needed given the actual conditions.

Now, onto the last pickle today (I hope) - I could use help confirming the correct part number of TTS as I still have no access to EPC due to upgrade to Xentry. There seem to be two p/n in circulation, 0045459124 and 0045459224 - one opens at 15C, the other at 20C, and some online portals list the as interchangeable but that's probably not the case given the different spec. Looks like mine is 15C, unfortunately the MB or VDO p/n is not on the switch itself.... So I'll appreciate some advice as I want to order a new TTS asap.

EDIT: Of course, video evidence below

 

TTS part # is 004 545 9224, confirmed & ordered through local stealership = €100 with the loyalty discount, could be worse!

 

Ladies and gents, the switch arrived today and turned out to be 004 545 9124 i.e. equivalent to 9224 - it has larger body and shorter pin, but specs are the same. At any rate, I swapped the switch, reconnected the wire, cranked the engine and after 1-2 sec she fired up as if she just rolled off the factory line back in 1979

 

Ladies and gents, the switch arrived today and turned out to be 004 545 9124 i.e. equivalent to 9224 - it has larger body and shorter pin, but specs are the same. At any rate, I swapped the switch, reconnected the wire, cranked the engine and after 1-2 sec she fired up as if she just rolled off the factory line back in 1979

Miko,

I am having an issue with my 380sl and wonder if it could be related. The question I have is if your car, when cold, would go to warm-up idle (950rmp) or would it run at normal warm idle (550rpm)?

 

NICE! :thumbsup:

 

Derek, idle worked ok so the car would run @ 950RPM until warm - once it was running it was ok, getting it started was the challenge.

 

OK, So I'm chasing something else. Thanks,

 

So what's wrong with your car when it starts? It drops to 550 even if cold?

 

It will crank right up, but will only go to 550-ish idle. If I try to drive it, it will bog down and stall. In rare instances, it will crank, but not start. Something is not telling the car that it's cold and needs to go to warm-up idle. Once the car is warm, it drives great.

 

Well, then it also could be the thermotimeswitch or CSV acting up. Have you tried disconnecting CSV and checking it makes any difference? If you follow my thread you'll see troubleshooting steps to determine if either component is faulty.

 

When I disconnect the CSV, the idle jumps up to about 1200 when the engine is either warm or cold.

 

Does the CSV spray continuously or just a few drops of petrol?

 

Brain fart, need to back-track. I pulled the plug from the idle air start valve, not the Cold Start Valve. Let me re-read that section above and try that this afternoon and let you know.
Thanks,

 

Reached out to Pierre Hedary (pierrehedaryandco.com) for advice and he said that it sounded like the WUR was overpressurizing the fuel system. I not familiar with the WUR, other than basic operation, so I'm going to have to dig into that a little.