amgmercedes

This isnt about my own SL, but someone else's.

My friend's 500SL has a problem wherein the engine sputters and hesitates when you step on the gas when the engine gets into normal operating temp.

Everything is fine when the engine is cool, as when you start it up and drive off in the morning. The trouble appears once the engine gets hot, about 100 degress or so.

Any ideas?

Thanks.

blueSL

Could be anything from fuel starvation to engine management to bad ignition/spark plugs. Typically, this fault could be caused by one of the engine management sensors going bad at high temperature causing the engine to mis-behave. The engine management system can only control the engine based on the information the sensors are telling it.

Only solution is to take it into the dealer who can do a diagnostic readout which may point to the problem.

morebhp

I had this or similar on my 94 SL500 - it ran fine until about the 6 miles mark then ran like a pig for about 10 miles then fine again. Also fine if used regularly.

Main Merce dealer did diagnosis, recommended and fitted new air mass sensor and return valve (I think this is what it was called - may have been regeneration valve). End result with diagnosis - I'm £1200 down and car is running just as bad as when it went in!

Back street dealer fitted two new distributor caps (about £230) and it solved the problem.

I'd suggest starting with the two distributor caps!

Obviously it could be something completely different, and in my case it could have been a combination of capos and air mass, etc.

Good luck.

Dudereeno

I have the same problem with my 1994 SL 500. I bought the car when it was 1 year old with less than 12,000 miles. Over the past three years this problem has cost me over $10,000 in botched/ineffective repair attempts by my dealership. Replacement parts have included:
2 fuel pumps
Distributor cap
Wiring harness
Spark plugs
Ignition control module (this cost me $3k for the part alone!)
Other minor parts etc etc etc, plus LABOR etc etc etc

Problem is still with me. After the car warms up (second start of the day) it sputters and feels like it's going to stall until I reach about 15 MPH. Then it smoothes out. Scary if you need full acceleration to pull into traffic or are sitting in front of a big truck at a stoplight and can't move when the light says GO.

Anyone have an idea? This post is old, it's now 2014.

ioang26

I am having a similar problem with my '86 560SL.If you feather the gas pedal the car will not stall but if you step on it then stall or would accelerate after 2 sec delay.I have changed a lot of parts too- fuel pumps,distributor cap,fuel distributor,fuel pump relay,fuel pressure regulator ,injectors and more.
Did you find what was wrong with your car?

Dudereeno

Well here is my LATEST update. First let me say that I have a great deal of confidence in my MB dealer. their mechanics have been superb with everything except this recurring problem.

In March of this year (2014) I took the car in and told them it was doing it again, despite over $10,000 in repairs over the past three years for the same problem. They assigned it to their most senior and supervisory mechanic. He's been dealing with this forever. Like yours they've done and replaced EVERYTHING conceivable. This time they found oil in the distributor and he thought he had it nailed. Apparently there is some sort of rod that comes out of the actual engine into the distributor. the seal around that rod was leaking oil into the distributor and they felt this was the problem. I told them that I am not spending another penny on the repair and that they should deliver on the promise to make this repair without me delving into my pocket again. The cost of over $500 for taking apart the engine and replacing this internal seal was waived. They did that repair. THEN while test driving it over a couple of days, the problem came back. So it's still not fixed and I go and visit the car once a week like it's in prison. It's in the #1 bay in their shop, up on a lift and won't move until they fix it. So far they've had it for a month. No one is assuring me any longer that it will be fixed soon, but they're trying. It remains to be seen. So in a nutshell... No one knows what it is yet.

scottejupiter

I feel your pain. My 1991 500SL has problems in the morning before it warms up. Doesn't want to go over 20 mph for the first block.

Gotten new plugs & wires, one distributor cap, new OVP relay. Not sure what else to try.

Someone said that they are slow in the morning until the catalytic converter warms up. But I don't think it should be this bad.

Once it warms up, shifts perfectly with lots of pickup.