no coldstart 500 SL

Hallo,

My car has a difficult cold start, about 5 sec. cranking. Then drives well.
I also think the ECU is failing (no kick down etc)

Today impossible to start, what can be the reason?

Thanks, Luc
1987 500 SL no lambda

Hi Luc,

please check 2 things:

1. Fuel pressure when cranking on flange to cold start valve
2. Voltage on cold start valve while cranking

Hi,

I checked voltage on cold start valve during cranking = OK
Also resistance on valve = OK (5 Ohm)
I can not check fuel pressure today.
(I can hear the fuel pumps running on ignition)

Thanks !
Luc

Hi Luc,

then I guess that you will see little or no fuel pressure. It might improve when you start ignition without starting engine several times before you finally crank it. If fuel pressure is bad, it can be

1. Fuel accumulator
2. Non-return valve on pump
3. Leakage of fuel form fuel distributor to air flow sensor
4. Leaking injectors
5. Leaking cold start valve
6. Leaking pressure regulator

Hello,

I checked the fuel pressures and is OK, 5.5 bar at cranking, and after cranking stays at 3 bar. Engine is flooded immediately, spark plugs are wet.
Ignition is OK, I have sparks.
So I think : bad injectors or leaking cold start valve?

Good morning
change your plugs to Sparkplugs made by NGK
BOSCH plugs are made often in Russia and have problems

 

Hi,

good hint from Andreas. If you have Bosch swap to NGK BP6ES.

If you have proper system pressure and holding pressure, points 1 and 2 are okay. Now open flap on air-flow sensor (after removing air filter) and light under fuel distributor. Is it wet there? Then remove thin hose on pressure regulator. Dry or fuel drops? If all that does fit, check injectors and cold start valve.

Hello,

I have changed injectors, now cold and warm start are OK so I suppose there was some fuel leaking from the injectors. The cold start injector is not leaking, but I am not very confident. Is it a good idea
to disconnect the csv electrically are better to disconnect the fuel line completely?
The only issu that is left is the high %CO (5 %)  When I adjust it to 2 or 3% engine becomes "unruhig"
I also checked for vacuum leakes with the brake cleaner method, no leaks.
Car drives very nice otherwise.
Thanks!
Luc

Hi,

I am still stuggling with the high CO at idle, about 5.5 %
Sparks = OK
Fuel pressures  = OK
no vacuum leaks.
When I disconnect the EHA at idle, the CO drops to 3.5 %
Any ideas?
Thanks!
Luc

Yes Russia have much problems

Gruss Karl