1980 450sl does not run when warm

On May 30, 1:21 am, "Tiger" <tiger0....RemoveThis@hotmail.com> wrote:
> Then adjust the fuel mixture with 2.5mm allen wrench in that hole by the air
> flap...It is too rich which is why it died when hot.

Tyger, the mixture must allways be adjusted with the car at normal
temp, isn't it?
My 2 cents: If you find lambda after the car is at normal temp,
measure the fuel pressure at the intake fule line: this pressure must
remain for 30 minutes or near that even with the car not running; if
not, you have a bad fuel pressure accumulator.
RSalles
 >> Stay informed about: 1980 450sl does not run when warm 

No, not necessirly... if you change the distributor, the car will not start
up, so you have to fiddle around with the mixture setting until the car
starts up.

Once the car is warm, you do the final adjusting. In this case, I am
assuming the car is running lethargically during the warm up... so by the
time it is warm, the engine will die from too rich of fuel mixture.

He/she didn't mention hard starting issue... which is what you are thinking
of. and the technique you are talking about is for static fuel pressure that
will tell you why you have hot start issue.
 >> Stay informed about: 1980 450sl does not run when warm 

On May 30, 4:07 pm, "Tiger" <tiger0....TakeThisOut@hotmail.com> wrote:
> No, not necessirly... if you change the distributor, the car will not start
> up, so you have to fiddle around with the mixture setting until the car
> starts up.
>
> Once the car is warm, you do the final adjusting. In this case, I am
> assuming the car is running lethargically during the warm up... so by the
> time it is warm, the engine will die from too rich of fuel mixture.
>
> He/she didn't mention hard starting issue... which is what you are thinking
> of. and the technique you are talking about is for static fuel pressure that
> will tell you why you have hot start issue.

As Tiger says, the basic mixture is set by the screw next to the air
flap (air mass meter). This should be adjusted when engine is warm.

During warm up (2-3 minutes) a warm-up regulator will enrichen the
mixture and gradually decrease the enrichment with the rise in engine
temparature.

Your situation could be, that your basic setting is too lean, but due
to the warm-up enrichement, it will run until warm, i.e. until
enrichment stops.
 >> Stay informed about: 1980 450sl does not run when warm 

On Jun 3, 12:44 am, Jens <j....DeleteThis@minnet.dk> wrote:
> On May 30, 4:07 pm, "Tiger" <tiger0....DeleteThis@hotmail.com> wrote:
>
> > No, not necessirly... if you change the distributor, the car will not start
> > up, so you have to fiddle around with the mixture setting until the car
> > starts up.
>
> > Once the car is warm, you do the final adjusting. In this case, I am
> > assuming the car is running lethargically during the warm up... so by the
> > time it is warm, the engine will die from too rich of fuel mixture.
>
> > He/she didn't mention hard starting issue... which is what you are thinking
> > of. and the technique you are talking about is for static fuel pressure that
> > will tell you why you have hot start issue.
>
> As Tiger says, the basic mixture is set by the screw next to the air
> flap (air mass meter). This should be adjusted when engine is warm.
>
> During warm up (2-3 minutes) a warm-up regulator will enrichen the
> mixture and gradually decrease the enrichment with the rise in engine
> temparature.
>
> Your situation could be, that your basic setting is too lean, but due
> to the warm-up enrichement, it will run until warm, i.e. until
> enrichment stops.

....on the other hand, if the engine previously has been running well
with the present setting of the mixture screw, you should not change
it but instead look the cause of the change!

Definately you are running too lean, since pressing the air flap
provides better running condition.

I can see two possible reasons for the lean mixture:

1) If you have an intake manifold vacuum leak, which allow air to
bypass the air meter (flap).

2) Defective oxygen sensor, lamda control circuit or frequency valve.

At normal operating the output voltage from the oxygen sensor will
fluctuate between 0.1 and 0.9 volts, where 0.1 volts represents too
lean mixture and 0.9 volts represents too rich mixture. If the oxygen
sensor is stuck in the "rich position", it will cause the frequency
valve to lean the mixture. Or if the frequency valve is stuck in the
"lean position" (either by itself or by wrong signal from the control
unit), you would have the same symptom.

When both above things are cleared, the output of the oxygen sensor
should fluctuate as said with a duty cycle around 50%. The ealier
mentioned mixture screw is used to adjust this.... but of course only
when everything else is OK.
 >> Stay informed about: 1980 450sl does not run when warm