missing

[Sam SL]

On my 71 with a recently top end rebuild, I experience a slight miss cruising between 3000 and 4500 rpm's with it most noticeable at 3500.  When I say noticable I mean the sound of the exhaust and the actual missing motion is slight.  The car otherwise run well.  Any clues?  I am thinking it might be something to do with a midrange adjustment in the injection pump.  By the way, I did not notice this before the rebuild.  Sam

Sam

[mdsalemi]

Sam,

Hopefully others will offer an opinion here as well.

My car has been rebuilt and restored.  The idle is extremely even and smooth at about 750-800 RPM.  Top-end running is also extremely smooth--accelerating on the highway from 70-90 MPH, for example.

However, similar to your observation, I notice a little and subtle "misfiring" at steady-state.  This would be around 45 MPH in 4th gear, which is probably just below the RPM's you indicate.  When NOT accelerating, but just doing 45 on level road, I can hear a little bit of misfiring and even detect a tiny bit of backfiring.  Very subtle--most people wouldn't detect it, but many of us 113 guys would.

Pete Lesler (well-experienced 113 guy known to many here) tells me that this is normal, and his 113's always did this.  His only suggestion is that MAYBE I'm "one-click" too rich on the FI pump.

Note also I changed plugs from Bosch W7DC to NGK BP6ES; this improved the situation a little bit, but it's still there.

Any expert opinions for Sam and Mike?

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[JPMOSE]

If it's a sputtering sound, you're likely running too lean.  Perhaps you could provide us with more detail about the sound you are hearing?

Best Regards,

J. P. Mose
1968 250SL

[Cees Klumper]

I had this "miss intermittent" after I first bought my car, while cruising at around 45 MPH. It went completely away without changing the IP settings (except for the idle mixture). I am not sure what cured it, but I did change the ignition over to electronic and rebuilt the ignition (051) itself. Another thing that might have influenced it was the accelerator linkages, which I serviced with new balljoints, new bearings on the stalk that goes across the valve cover etc.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[JimVillers]

Sam ... I would first investigate the ignition system.  A distributor rebuild and an electronic unit would be benificial but new plugs and an inspection and cleaning of the rotor, cap and plug wires and the testing of the plug wire ends will probably solve your problem.  Pay particular attention to the wires wire loom holders and wire ends.

Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor