vorstellung 450sl from California 1979 with TSZ-4

Hello,
New member here, from California with some ignition issues. Thank you for this site, I could download the correct testing procedure, the Mercedes CD manual that I have did not have the correct testing procedure for the R107 / 450sl 1979 with 46Kkm/ with he breakerless distributor.
In my case once the misfiring started, I pulled over and let the engine cool... it was a hot day, not even 20C, but the coil was very hot. I managed to drive home stopping every 10min. I installed one of the Jeep coil and it ran fine, albeit the specs are different. The last test drive was good but after 20min the misfiring and loss of power was very noticeable. Let the coil cool for 10 min while checking resistance numbers and realized that my voltmeter is not good enough to measure low resistance, so I will use a differential method. The engine restarted and had plenty of power to go up our many hills in San Francisco. Now I am back to testing the various output because I have the right instructions. Now I will be able to so some tests when the ignition starts to fail after 5 to 20 min.

I was lucky to find 2 450 at the local junkyard and retrieve 2 ignition box

I hope that google translate did not make too many awful mistakes

Cheers
Michel

Hallo,
Neues mitglied hier, aus den USA. Vielen dank für diese seite, ich konnte das korrekte testverfahren herunterladen, das Mercedes-CD-Handbuch, das ich hatte, nicht das korrekte Testverfahren hatte, weil unser R107 / 450sl 1979 mit 46Kkm / den breakerless Verteiler hat.

In meinem fall, als der Aussetzer losging, fuhr ich los und ließ den motor abkühlen ... es war nicht heiß, die außentemperatur 20 ° C, aber die spule war sehr heiß. Ich schaffte es alle 10 minuten nach hause zu fahren und anzuhalten. Ich habe eine der Jeep-spulen installiert und sie lief einwandfrei, obwohl die technischen Daten unterschiedlich sind. Die letzte Probefahrt war gut, aber nach 20 Minuten waren fehlzündungen und stromausfall sehr auffällig. Diesmal hörte ich nicht auf und schaffte es kaum nach hause. Lassen sie die spule 10 Minuten lang abkühlen, während sie die widerstandszahlen überprüfen, und stellen sie fest. Mein Voltmeter ist nicht gut genug, um einen niedrigen Widerstand zu messen. Daher verwende ich eine Differentialmethode. Der motor sprang an und hatte genug kraft, um die vielen hügel in San Francisco hinaufzufahren. Jetzt bin ich zurück, um die verschiedenen ausgaben zu testen, da ich die richtigen anweisungen habe.
Jetzt kann ich so einige tests machen, wenn die zündung nach 5 bis 20 min ausfällt

Ich hatte das Glück, 2x 450sl auf dem örtlichen Schrottplatz zu finden und 2 Zündboxen zu holen

Ich hoffe, das google translate nicht zu viele schreckliche Fehler gemacht hat

Grüße

Michel

Hi,

am I right that the 1979 450SL is no D-Jetronic? Is, at least, the ignition system similar?

Best regards,
Recardo

Dear Volker,

thanks for your explanation. I am always impressed about this incredible knowledge. Good to have you.

Best regards,
Recardo

Hi, it has been a long time to update my post, I hope that everyone is fine.
I found 2 extra switchgear at the local junkyard and the engine started in the driveway, for a few minutes run. One of these switchgear is installed, and I have another one ready if the engine stops running to do test and eventually do a quick road side swap.

Also in case the switchgears from the junkyard have the same issues I retrofitted a MSD CDI box to connected to the electrical system. I disconnected the coil wire and the switchgears plugs, and made a crude connection to the Green wire from the distributor which is a non standard "phono jack" or "radio antenna jack" This will be good for testing but in the future I will make a weatherpack connector if needed.

As soon as we are allowed to venture outdoor, we will take the little car for a drive

Thank you for the wealth of information available on the site, I have made a list of what to look at for the next roadside repair...

Stay safe, well and resilient

Michel

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 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

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

Hi Volker,
Thank you for this precision, it makes sense as the 450 last month of sale for the US was March 1980, before the release of the 380. It is common at least in the US to have an older model with newer model parts. It is a challenge for these overlapping years when trying to find what should fit.
From the documents in the trunk you or one of this board members can probably have more insight.
Best,
Michel
 

here we go for your collection

Engine 117985 12 033539
trans 722004 02 108258

 

Best

Progress made: I secured the pressure test gauge to prevent the hoses from touching hot engine surfaces... and did the usual drive until the engine started to act up, usually 3 to 5 miles. Pop the hood installed the gauge on the fender, secured it with a large magnet and a padding from an old inner tube.
As soon as the engine reaches 2000 to 2200 rpm, the control pressure drops from 3.5 bar to 3.2, engine misses, pressure drops further to 3 bar... let go of the throttle, pressure comes back to 3.5 with full power as long as the rpm is below a certain rpm.

Time to check the fuel pump when it is warm. I did an amp test last year, but it was on a cold engine.

Hi Volker,
Success, I bypassed the fuel pump relay, drove 16 km the first day on city streets. I then secured the hood to prevent it from flying open, the only way to see the fuel pressure is to have the gauge being held with a large magnet on the fender and a piece of inner tube between the magnet and the fender paint!

Then I went for 45 km without hesitation even on our steep uphill freeways... going 110km (speed limit almost observed), fuel pressure steady at 50psi...

Now I have to find the culprit, on either the fuel pump relay or the ignition relay circuit -the one under the fuel pump relay- that I removed after the failed test in April.

Thank you for your suggestions, will post progress as it is always good to convey our findings, failure or success.

Best,

Michel

P.S: now I have to figure out why the E32 has high Nox! No code founds, I need to get a copy of INPA 3.0

It never stops, I repeated the fun ride... at some point... hesitation in a turn... but there is still plenty of power with a bit a rich exhaust ... then engine quits and smell of gas.... that was an easy one, fuel hose from fuel filter to accumulator cracked, at least we did not have to call the fire department...
Cheers
Michel