1986 560sl very sluggish when step on gas - PeachParts Mercedes-Benz Forum

robaincltnc · #1 07-31-2005, 08:37 PM

Does my car have an air mass sensor? Could my problem be a clogged fuel filter. When I step on the guess the vehicle is very sluggish and fights for acceleration until finally it let's go and gives me a couple of G's..I noticed some threads speaking of this sensor but most of the vehicle examples were newer than my vehicle. Thanks for any help and/or advice!
rob armstrong

mattcara · #2 07-31-2005, 10:46 PM

its normal to be sluggish.

i have an 88 560SL

they are powerful cars,, but they are also heavy tanks..

only light cars light porsches are fast off the line.

dont worry about it or spend unessessary money trying to fix something that isnt wrong.

Strife · #3 08-01-2005, 12:18 AM

Keep in mind that unless it is manually shifted to "B" first, or has been modified, the car starts in second gear.

t walgamuth · #4 08-01-2005, 12:19 AM

you have a vacuum leak. check vac lines. i am assuming you know how it is supposed to feel.

tom w

robaincltnc · #5 08-01-2005, 07:11 AM

Thanks Tom..I hope that this is all that it is..MattCara and Strife.. I know they car isn't the fastest off the line but this is something different. It likes the car boggs down, the efficiency meter is burried and the car barely moves until...bam, it takes off! So a vacuum leak? I'll have to get it to my Indy. Any idea of where the leak may be from?

robaincltnc · #6 08-08-2005, 02:43 PM

I was thinking vacuum line but my problem is intermittant. I drove the vehicle the other day w/o any problems at all. Today, the problem was back. The engine bogs as I accelerate and then boom..it takes off. Any other reason for this other than vacuum. Could it be a clogged fuel filter or something to do with fuel?

mattcara · #7 08-08-2005, 02:51 PM

Rob.

you should have it checked out then. I just meant that our SL's are heavy and off the line wont be too qucik. but you seem to have a legit problem..

i just try to help out fellow SL's enthusist. because our cars arent cheap to fix. and most of us, will spend unness $$ to make sure our babies are ok....lol

Im having a dilemma as we speak. I have written a few threads about getting my SL to be a smoother ride. and im still not sure if its normally a bit ruff rider or if i shouls investigate and start replacing suspension parts~!

MrCjames · #8 08-08-2005, 02:51 PM

It can be several different things but here is something off the top of my head. When the syptom reoccurs you might want to try and perform a fuel volume check. 1 Liter in roughly 30 seconds.

robaincltnc · #9 08-08-2005, 03:08 PM

What is a fuel volume check? How do I perform this?

MrCjames · #10 08-08-2005, 05:24 PM

The "volume" check determines the fuel pump(s) ability to deliver adequate fuel based on performance demand. Hard throttle means increased demand on the engine and during this time the engine requires more fuel to develop the smooth performance anticipated by the driver. Low volume from one the fuel pumps can, and often does, contribute to sluggish engine performance during hard throttle situations. I am not certain your vehicle is suffering from a bad or faulty fuel pump but for the length of time it takes to perform this test it is time well spent.

Disconnect the fuel return line after the fuel pressure regulator (bolted to air/fuel mixture housing) and connect a hose to the outlet side. Place the other end of this hose into a glass container (.5 gal or larger), cycle the key several times to determine the volume. If you are savvy with electrical you can remove the fuel pump relay then bridge the fuel pump connections, this is a little tricky on the 107 chassis. If you need some pics to guide you along I might be able to muster a few of them up.

Roncallo · #11 08-08-2005, 10:21 PM

Check your ignition timing. 560SL are not sluggish. They may not be the fastest cars off the line with 2.47:1 gearing, but they are still under 8 seconds 0-60. Hardly sluggish even starting in 2nd.

John Roncallo

robaincltnc · #12 08-09-2005, 08:46 AM

Mr. C.the economy guage is buried when I am having the sluggish problems...however when the car is running fine the gauge works as normal (meaning I really have to step on the throttle to bury it)..note that fuel pumps do whine on this car. Have been whining for awhile. I was told that was normal for an aging fuel pump.

t walgamuth · #13 08-09-2005, 09:31 AM

guage is nothing but a vacuum guage, so if it is buried that means low vacuum. so this could support the idea that you have a vacuum leak. i suggest checking all the soft connecting parts in the vacuum system. these often work loose with age. if you find loose fittings you can temporarily seal. perhaps but best to replace them. i have seen people check for vacuum leaks by spraying either on each connection with the engine running. if it speeds up you found the leak.

happy hunting

tom w

MrCjames · #14 08-09-2005, 06:44 PM

Hi Rob

If you have a test ignition coil available to you, try that and see what happens. Also double check your distributor cap around the center terminal, look for a black ring surrounding the terminal (carbon buildup), this is an area that is often overlooked as a potential problem.

spanish cossie · #15 08-21-2005, 02:35 PM

i know just what you mean, my 190E 16v is the same, floor it at any thing under 4,000 and it's as flat as a f**t, gets to 4,000+ and lifts off like a rocket.

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