SL/R129: 1990 500SL stalls, gauges wacky
Thread Starter
Junior Member
Joined: Apr 2006
Posts: 18
Likes: 0
From: Ontario, Canada
R129, W124
1990 500SL stalls, gauges wacky
Hey folks, I'm hoping someone might have some insight into this, no comments on this post over at Mercedesshop:
If I start my 1990 500 SL after it has been disconnected from the battery for awhile, both the engine and the instrument cluster are fine (ECU has been reset??). However after shutting down long enough to gas up, and restarting, the engine stumbles and stalls and the gauges go wacky. The tach will show slower than the engine is running, the fuel economy gauge bounces back and forth like a pinball machine, and the other gauges may or may not work at all.
If I do get the car moving (by not accelerating too hard) the speedo underreports my speed by about two-thirds. And the car will surely stall again at the first light. Once up to speed though, its fairly smooth.
Disconnecting the battery for awhile starts the process over again.
Help!!
If I start my 1990 500 SL after it has been disconnected from the battery for awhile, both the engine and the instrument cluster are fine (ECU has been reset??). However after shutting down long enough to gas up, and restarting, the engine stumbles and stalls and the gauges go wacky. The tach will show slower than the engine is running, the fuel economy gauge bounces back and forth like a pinball machine, and the other gauges may or may not work at all.
If I do get the car moving (by not accelerating too hard) the speedo underreports my speed by about two-thirds. And the car will surely stall again at the first light. Once up to speed though, its fairly smooth.
Disconnecting the battery for awhile starts the process over again.
Help!!
Thread Starter
Junior Member
Joined: Apr 2006
Posts: 18
Likes: 0
From: Ontario, Canada
R129, W124
Any other ideas? It does seem like the engine is getting too much fuel - at least the fuel gauge seems to indicate that.
We disconnected the cold start sensor and that did work for awhile - connected it would stumble, disconnect and it would start up well and run well, but then when we shut down and restarted it would stumble again even though the sensor was still disconnected. Arggh.
We disconnected the cold start sensor and that did work for awhile - connected it would stumble, disconnect and it would start up well and run well, but then when we shut down and restarted it would stumble again even though the sensor was still disconnected. Arggh.
Member
Joined: Mar 2004
Posts: 132
Likes: 2
From: Dallas, TX
2007 Mercedes SL550 Sport
jumping gauges
having the same problem on my 97 SL320. the battery light starts to flash, and the oil and other gauges start jumping around. the battery is new and it is charging close to 14. mechanic said these cars had a problem with grounding. any ideas???
Member
Joined: Dec 2005
Posts: 89
Likes: 1
From: UK - south east
'93 SL500
Do your Tell-tale lights extinguish intermittently when they shouldn't?
Bet's on your ignition switch...
It's well documented on several forums that SL ignition barrels are prone to failure. Had to replace mine a while back...all OK now
http://www.mercedesshop.com/shopforu...light=ignition
Bet's on your ignition switch...
It's well documented on several forums that SL ignition barrels are prone to failure. Had to replace mine a while back...all OK now
http://www.mercedesshop.com/shopforu...light=ignition
Thread Starter
Junior Member
Joined: Apr 2006
Posts: 18
Likes: 0
From: Ontario, Canada
R129, W124
Well after many months and lots of trial and error (including changing the ignition) we got to the bottom of the problem: bad ignition coil.
Put a new one in and it ran as smooth as a dream with no bouncing gauges.
Who'd a thunk it.
Give it a try and let us know if that fixes your problem.
Put a new one in and it ran as smooth as a dream with no bouncing gauges.
Who'd a thunk it.
Give it a try and let us know if that fixes your problem.
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