Help - intermittent momentary engine miss

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Help - intermittent momentary engine miss

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Mercedes Forum >> Mercedes Benz Models >> Mercedes SL Class >> Help - intermittent momentary engine miss

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Help - intermittent momentary engine miss - 5/27/2008 1:42:55 PM

backert1

Posts: 2
Joined: 4/16/2007
Status: offline

I could really use some help with this one. I own a 93 500sl with ~84,000 miles. Last summer and this spring I have noticed a very slight missing that occurs is noticiable at any constant engine RPM or road speed. The missing is very short lived, just feels like a little tug backwards. Most of the time it doesn't even show up on the tach - other times I believe I can catch a fleeting every so slight dip in RPMs. It can occur when the car is hot or when cold. It can occur when the weather is hot or cold. It can occur if the gas tank is full or near empty. It can occur if the car is idling or moving at 90mph. It can occur some days and not at all on other days. It can occur every few seconds or every few minutes. The only things I can tell is that when it occurs, the engine speed is steady (never notice anything during accelration) , and when it occurs it appears the missing seems to be consistent in time from miss to miss although that miss interval may be different different days. Any ideas? If it had any dependence on RPM, temp, car speed, gear, tank level, etc it would be easier to diagnose. Seems to irregular to be fuel filter, injector, fuel tank pressure, fule distributor, etc....... I worry about impending failure of some component but don't have an idea of where to start.

Thanks,

Todd

Post #: 1

RE: Help - intermittent momentary engine miss - 5/27/2008 10:11:40 PM

brookings

Posts: 135
Joined: 6/1/2007
Status: offline

do you have any service records showing that the spark plugs, plug wires, distributor cap, and rotor been changed since new? If you change out the plugs make sure to use Bosch, don't put in cheap.

(in reply to backert1)

Post #: 2

RE: Help - intermittent momentary engine miss - 7/4/2008 12:25:10 AM

bilby

Posts: 1
Joined: 7/3/2008
Status: offline

Hi,

I''m a new member and have just seen this posting.

I''ve got exactly the same problem that you describe in my ''96 SL500. Very rare, unpredictable and only at constant revs - occaissionally mine even cuts out (re-starts fine). Other than this, the car runs fantastically.

Can you please let me know if you ever found a solution to your problem please ? I''ve got new Bosch plugs and the leads seem all fine.

Thanks & regards,

Gareth.

(in reply to backert1)

Post #: 3

RE: Help - intermittent momentary engine miss - 7/17/2008 12:50:28 PM

jshyshka

Posts: 1
Joined: 1/1/2008
Status: offline

I have a 98 SL 500 (don''t know if things are the same on your 93 or 96) and it was doing the same thing ... ended up being the Mass Airflow Sensor (MAF) ... I had it replaced and it runs fine again. In some cases you can get away with just cleaning them but mine was in bad shape.

(in reply to bilby)

Post #: 4

RE: Help - intermittent momentary engine miss - 9/2/2008 9:46:18 AM

lylehutchison

Posts: 1
Joined: 9/2/2008
Status: offline

My 74 450SL does this, sounds identical. Found no pulse to the injectors. Have in garage now. The distributor has points for powering the injectors 2 stokes before the spark which I suspect. Called trigger points and are $588. Let me know please if you solve your prob. I''ll let you know what I find on mine.

(in reply to jshyshka)

Post #: 5