Engine misses when accelerating at low rpm

[n/a]

bonjour!!

After a smooth 100 miles ride to eastern Long Island on friday evening (cruising at 75 mph) I noticed the car starting to miss when I start at red lights and when I accelerate from low speed (5/10 mph, engine in low rpm mode, usually below 20rpm). It doesn't happen all the time, but tends to happen when I accelerate strongly.

I met with Doug Kim on saturday and we test drove the car.... Only to observ the same symptoms. The car was serviced last week (new thermostatic valve) and I believe the fuel pump might have been cleaned..?!?!
we noticed it even occasionnally misses when in N position and we run the engine.
Lastly, I noticed last night on the way back some kind of metallic noise when I accelerate at low rpm/low speed when in 3rd or 4th gear....I am not sure about this noise, wether it is the engine which is worned out or some part from the exhaust that is getting loose.

We both thought it would be an interesting question to ask here... any insights???
As for the ride, It was VERY nice to be cruising at 80mph top down last night around 10pm on the way back to New York...

Fabrice
Silver 1971 280 SL
New York City

[Naj ✝︎]

Fabrice

Bonjour.

Could be bad driving [:p]

I would check the vacuum pipe from distributor to inlet manifold throttle venturi. May have just come off at the throttle body!
Good luck ( sorry knowledge of French very limited - bon chance??)
naj

naj
'Kloines Scheisserle'
65 230SL
68 280SL

[n/a]

Talking about bad driving....you want to start a topic there? ....
...Sorry, but we don't drive on the wrong side of the road........   ...

I will try to check tonight, gives me an excuse to use the car!!!
To me, it could sound like air some where, the fuel tank hose was also changed last week...


Fabrice
Silver 1971 280 SL
New York City

[George Davis]

Fabrice, I suggest you check your points.  Mine misfired at low rpms like yours.  The points were burned and dwell way out of spec, and they were fairly new points.

George Davis
'69 280 SL Euro manual

[Cees Klumper]

If it is the points, maybe this will be a good time to consider switching to electronic ignition.

[ja17]

Hello Fabrice,
A good place to start is the spark plugs. They can give you a hint on where to start looking. Learn to read them. If the new parts in the injection pump are causing the injection to run lean, the spark plugs will fail. In this circumstance, the spark plugs will be very clean and white, instead of the optimal tan or brown color. Often the exaust pipes turn a very light grey if a lean situation is present. Let us know what you find. Good luck.




Joe Alexander
Blacklick, Ohio

[n/a]

the points are new but I think Joe is right on the spark plugs. The car is at the mechanic today, I will pick it up tonight. the first reaction of the mechanic was to change some of the spark plugs as well as modify the richness of the mixture (sorry, don't know how to say it in proper english - no offense, hope no-one from Oxford is reading !!).
I should have an answer tomorrow hopefully...

Fabrice
Silver 1971 280 SL
New York City

[n/a]

Even though I didn't test drive the car, it looks like it was the spark plugs... I saw them, they were very black, no trace of white though. They had been in for the past 2000 miles, driving both in the city and on the highway... (probably troo much city anyway)
I left the car at the mecahnic to have a couple of hoses changed, following his advice.
Next step, I leave the car at a body shop for a repainting of the lower back fenders to original silver + hopefully pinstripe removal....Hoping to have the car nice and clean for august 17th!!!

Fabrice
Silver 1971 280 SL
New York City