SL/R129: 1998 SL500
Thread Starter
Junior Member
Joined: Jul 2018
Posts: 24
Likes: 0
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
Super Member
Joined: Aug 2019
Posts: 702
Likes: 207
From: Lutz, FL
1997 MB SL600
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.
Thread Starter
Junior Member
Joined: Jul 2018
Posts: 24
Likes: 0
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.
Senior Member
Joined: Dec 2014
Posts: 326
Likes: 47
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; Jun 19, 2021 at 10:05 PM.
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Senior Member
Joined: Apr 2019
Posts: 428
Likes: 96
From: Houston
001 s600, 94 sl600
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.
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Thread Starter
Junior Member
Joined: Jul 2018
Posts: 24
Likes: 0
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
Senior Member
Joined: Apr 2019
Posts: 428
Likes: 96
From: Houston
001 s600, 94 sl600
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.
