D jet problems continue

Hello

I would gratefully accept your advice on my w108 3.5 which continues to stall when warm and then cannot be started (won’t even turn over). Therefore can only drive for distance of around 2-3 miles. 

have checked MAP and is fine 

my mechanic is also stumped.

please advise next steps!

I had this problem earlier and it has now recurred 

Hi Unknown,

I cannot address you directly as I do not have your first name.

If your starter does not even turn, then it has nothing to do with injection. You have an electrical problem with your wiring harness or battery.

Dear Dr,

Sorry for the unclear symptoms. The car will start and run well when cold. When the engine is warm it will cut out at idle. Then it will turn over for a short period and then fail to turn over. If one leaves the car for an hour or two it may start and then the cycle repeats.

I wonder if somehow engine is getting flooded during warm idle ?

Kind regards

Hemal

Occasionally there will also be sawing of idle when cold but infrequently.

Unfortunately I do not have much experienced mechanics in such vehicles in my areas so not sure how to proceed

Best,
Hemal

Hi Hemal,

I am Volker, also a Dr. but that is a different story. So please just call me Volker.

Maybe I fall over your word "engine turns over". I interpret that it does stop running, Then it cranks slowly a little and then even cranking does not happen.

Hi Volker,

Yes you are correct. So you don’t believe it’s a D jet problem?

Kind regards

Hemal

No,

starter has nothing to do with D-Jetronic.

Thanks but the car will stall when warm to reach this situation. What might be the cause of that ?

Ignition switch, wiring harness, battery, ...

Hi Hemal,
if there were an extreme leakage at the cold start valve and / or the injectors, one cylinder could be flooded with gasoline and get totally blocked. The starter couldn't turn the engine anymore until the fuel had dropped down (thinning the engine oil) or has evaporated.
I think, you should check the fuel pressure, especially the behavior after switching ignition off.
Use a t-piece to connect the manometer instead of connecting to the hose of the cold-start-valve because this could be the reason for the leaking.
The system has to hold the fuel pressure for a while...

Please do this and tell us the results.

Regards
Norbert

Hi Norbert,

sorry but I consider that unlikely. If a cylinder was filled completely with gasoline and starter would not be able to crank engine, then it would not be possible again after some minutes. Gasoline would not escape from such a cylinder so quickly.

Anyhow, Hemal should hear the difference between a starter that switches on and cannot turn the engine and a starter that does not turn or is starting and stops again due to loss of power.

Hi Volker,
in this case I have to disagree with you.
I have experienced this myself several times.
The cylinder has not to be filled completely, I think about maybe 80 ccm of fluid will block the engine.
But it doesn't take long until enough has flowed down through the piston ring joints so that the engine can turn again.
Of course, this cylinder doesn't start running again straight away - but it does after a short time.

Let's wait for the results of Hemal's measurements...

Regards
Norbert

Hi Norbert,

again what learned - I never came across such a horror case.

I had this problem once. Caused by old starter wires. Worked fine when cold then wouldn't start when hot. I replaced all of my starter cables and wires and fixed the problem.

Thanks all for your input. Maybe I am not stressing sufficiently that the primary problem is a too low idle during warm running which is causing the stall. Then only do the starting troubles begin…

What is the cause of too low warm idle?

Hi Hemal,
I'm sorry for having misinterpreted the situation.
I read your first posting 'engine turns no more after having stalled' and not your next posting 'engine turns for a short time, then doesn't turn further on'.
If the cylinder were filled with fuel, the engine would be totally blocked.

We have to begin at the beginning.

As Volker wrote before, you have to check the electrical wiring, battery and so on.
The D-Jetronic is an electronic device and the electric system of the car has to be o.k. for a correct operation of this system.

Then we need some more information:
Has the valve clearance been checked?
Was the ignition checked, adjusted?
How many revs is the idle?
Did you measure the CO?
Did you take out the spark plugs, are they wet, black or...?

Maybe you cannot answer all the questions at this time, but we need a starting point.

You will find useful information, for example how to adjust idle here: jetronic.org/de/jetropedia/107sl-wsm-con...-107sl-ri-engc-m116D ?

Regards
Norbert

Hi Hemal,

the AAV causes idle to go down when engine gets warm. It should go down to 750/min and you have to adjust idle rpm on warm engine via adjustment screw. Then cold engine can run - depending on engine temp - roughly 1000/min. If it runs much faster, than your AAV is an issue.

But the fact that it won't start again unless you wait some minutes is a different one that seems to be related to wiring and ignition lock.