vorstellung 450sl from California 1979 with TSZ-4

A bit of an update... I found out that the distributor cap had a damaged post, more arcing than the other. It was replaced but no improvements... Then I finally found the non resistor spark plugs and used the NGK BP5ES, properly gaped at 0.7mm -the packaged plugs are not gaped for our specs- I did a quick 7 km drive in town, and there was a lot more power on the steep uphill streets that we have here, and no misfire.
I will do a longer test drive during the week as it will be easier to get a tow truck if needed.

Another update... after another failed test drive, I finally bought the right fuel pressure test gauge, the first one did not have any of the right fittings, thank you amaz@n!

So it seems a bit lean when the engine is running, pressure is 3.5 bar or 50psi, recommendation are in the 2.9 to 3.2 bar. Yes the engine misses upon initial acceleration....

Best,
Michel

Hi Michel,

well control pressure depends on

• model year: 79 or 80
• WUR number: For 79 should be a 0 438 140 056
• Vacuum connected or not
• If you have WUR 056 and vacuum is connected then control pressure of 3.4 - 3.8 bar is okay

Hi Volker,
thank you, yes, I had to go back to the WUR number, it ends in 061 so it is withing specs, with vacuum connected.
Must be something else...

Otherwise at full throttle it runs very well! Idles as should be in the 600 to 650 rpm
Best,
Michel

Hi Michel,

061 seems to be the wrong one for your car.

thank you, this is a federal model initially from Chicago. I have a very strong belief that due to the low mileage nobody has ever done anything to it... but us... 12Kmiles when bought in the early 90's... 29Kmiles now with trouble free years... until 2018...

I started to check for vacuum leaks... nothing obvious, but a low manifold vacuum on the blue line to the EGR control... it was 10inch of mercury, I am starting to replace rubber connectors... now at 12inch of mercury... I guess I need to convert to Euro units...

Drove around the house to check power due to our steep hills... seems fine today.
Best,
Michel