SL/R129: 1998 SL500
06-17-2021 | 10:22 PM
#1
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From: las vegas, nevada, usa
1998 Mercedes SL500 245,000 miles
1998 SL500
I have a 1998 R129.067 SL500 M119.982 that has been in limp mode and I cannot figure it out. The car idles great, revs great in idle but once you shift into gear the limp mode starts so I have changed the MAF, MAP, throttle body and all vacuum lines but still in limp mode. What have I overlooked?
Has anyone got a good recommendation for a scanner using the 38 pin connector. Something that covers all systems on my 98 R129. I have been researching and still no better off than when I started.
Thank You for your help
David Ball
Has anyone got a good recommendation for a scanner using the 38 pin connector. Something that covers all systems on my 98 R129. I have been researching and still no better off than when I started.
Thank You for your help
David Ball
06-18-2021 | 09:42 AM
#4
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I had the BANG once at around 204K miles, new tranny time.
For about a $100, the dealership or an indie will tell you what's wrong with your car.
It's way better than guessing and throwing parts at a car.
For about a $100, the dealership or an indie will tell you what's wrong with your car.
It's way better than guessing and throwing parts at a car.
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FATHERTIME (06-19-2021)
06-18-2021 | 06:47 PM
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From: las vegas, nevada, usa
1998 Mercedes SL500 245,000 miles
06-18-2021 | 06:50 PM
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From: las vegas, nevada, usa
1998 Mercedes SL500 245,000 miles
yes forward and reverse works fine but no quick acceleration just cruising around town as long as I take it easy with the acceleration once I try to gas it then limp mode kicks in.
06-19-2021 | 10:00 PM
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From: Yorba Linda CA
94 SL320 98 SL500 99 SL600 07 SL55
I would put a smoke tester on it to begin with to eliminate any vacuum leaks. they are cheap on ebay. And maybe a new fuel filter. Pull the vacuum line off your fuel pressure regulator and see if fuel is in the vacuum line, if so replace regulator. A SDS scan is a good investment too
Last edited by FATHERTIME; 06-19-2021 at 10:05 PM.
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06-21-2021 | 12:22 PM
#8
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Check the 'transmission upshift delay' module. This delays the upshift 1-2 when cold (first start) to shorten the time to catalyst light-off. When it is not working it will trigger limp mode.
06-21-2021 | 04:59 PM
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From: las vegas, nevada, usa
1998 Mercedes SL500 245,000 miles
I would put a smoke tester on it to begin with to eliminate any vacuum leaks. they are cheap on ebay. And maybe a new fuel filter. Pull the vacuum line off your fuel pressure regulator and see if fuel is in the vacuum line, if so replace regulator. A SDS scan is a good investment too
06-22-2021 | 12:07 PM
#11
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Limp mode why?
Alas, The famous bad wiring insulation problem may be the problem. It starts just as described. All the wiring inside the bundles turns to DUST--with to come shorts-and component burn outs. Slit a wiring bundle where it is hot and examine the wires inside. Typically the MAS sensor , fuel injection, and main engine wiring harnesses are affected and must be rebuilt. NOS parts are NLA. There is a fellow up in NE who rebuilds these parts for fair cost.
