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Alright, I recently bought a 1995 Mercedes SL500 with 97,000 miles on it. Got new valves and all the engine harness (wires) redone using insulating tape, new spark plugs and all parts related. Car idles perfect and accelerates well, the problem comes when I press on gas pedal little too hard to the point when tires are about to lose traction, car shuts itself down. As well as when I brake. This is not happening all the time. I decided to test it, went on a "dirt" road and tried to spin the tires. It would not spin the tire with/without abs system, but instead car would shut itself down. Then when I put it in park and start it, it would start right back and so on. Also on freeway when there is little bumps and tires jump up and down (just a little) car would seem to almost shut down(loses power), but after giving it little gas while in motion it goes back in normal Not sure if this is related, but when I turn on the ignition in position 2, the tachometer arrows vibrates so to speak What might be the issue? Thanks in advance.
 

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2013 SL550 Grey/ Red/Black Ash wood with every option
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1995,
There is a lot of reading on the internet regarding this issue. You state that you redid "engine harness (wires) redone using" insulating tape. Is this on each individual wire, or just wrapping the whole harness? The way the shielding crumbles, if you just wrapped the whole harness, you'll have issues because of contact between the wires. There are two harnesses to replace, the engine harness and the battery harness. If I remember, the battery harness connects on the main starter lug and has two other wires, I believe they are oil pressure and oil level, it's been a long time since I had my SL500. However, you'll need to check the harness to the throttle actuator. Your SL500 has ASR, which is designed to reduce power if the rear wheels break loose. And you have the ASR switch at the accelerator pedal too. Anyway, just my thoughts on this. If I had to speculate, I'd say the culprit is the throttle actuator itself, or the harness. Keep us posted on what you find. I kind of recall that when I replaced both harnesses I removed the throttle actuator and sliced open that heavy shielding and found all wires were a crumbled mess. If I remember correctly, with new wire, heat shrink tubing, and was able to solder in new wires from the plug end to the actuator. You can only work with the plug end just so far, as it doesn't come apart. I don't recall how far I went into the actuator, probably just work with what was exposed, and hoped for the best. I never had any ASR issues with mine before or after.

Thorgod
 

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Discussion Starter #3
Right, yes I redid each individual engine harness (wires) using insulating tape. The top wires that go on top of the engine, I believe to the sparkplugs, as well as the lower wires that are connected to the bottom where oil panel is. This is where the confusing part comes to play, I don't have neither ASR nor other warning light related to traction control on. I just tested and did a burn out on a flat ground with tires facing forward using brake and gas pedal at the same time and it worked with no problem what so ever. Couple minutes past by, while I was take a turn to a higher ground so to speak, car turned off. Put it in park, started right back
 

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Alright, here's what happened. I took the car to mechanic shop that specializes in classic Mercedes Benz vehicles and on my way there, car turned off twice without a reason, at this point it didn't even do it when the tires spin. And on one of such stops it was an a stoplight, turned key to position off and then back to second position, when the car is waiting to be started. Every light on dashboard lit up expect "check engine" light, and I didn't here the fuel pump work. I unplugged the battery, waited for about 2 minutes. Putted back on and car started working as it's brand new. I got to mechanic shot, on the computer he didn't find any error codes, expect that the soft top does not work and the rollbar doesn't go down (it's in up position). Our guess would be that the computer thinks that the car is about to roll over and that is the reason it cuts off the power, or the ignition switch is bad. He told he that he had a customer with same problem and he end up spending $12,000 and still couldn't figure out what's going on with the car. Dealer didn't not either, that guy is selling the car now, in great condition. But there is that problem. Overall my advice would be to if you disconnect the battery and the car does the same thing over and over again, it is most likely something wrong with electronics, there is bunch of things that can go wrong with this car, unless you are willing to spend crazy amount of money on the car or potentially replace the whole electrics in the car, sell it. One of the reasons electronics go bad is that in 1995 they used recycled plastic "planet friendly". And it is much different from the actual German type. Hope it was useful! Have a great life
 

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R129 500 SL 1991
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Our guess would be that the computer thinks that the car is about to roll over and that is the reason it cuts off the power, or the ignition switch is bad...
Power is not cut when roll over bar deploys. Go with your second guess. Sounds very much like the ubiquitous ignition switch problem. Or the wiring harness.
 

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Try replacing the crankshaft sensor. Had an issue with my engine just shutting off once the engine was hot and it was the sensor.
 
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