280SL reacts too slowly

[wildatheart]

I have noticed that when I put my foot down hard from standstill, the revs don't rise immediately; there is a short delay, perhaps half a second or so, before the revs rise and the car pulls away. I am not sure if it has always been like this, but is this how it should be?  It happens with the auto box in all Drive settings, from 1 to 4. There is a more instant response when the car is in Park or Neutral, when the idle speed is higher, of course. Perhaps my car idles too low when it is in gear with the brake on (my guess would be around 500 rpm)? Or should I look at other causes first?

many thanks for any thoughts

Jaap

1970 280SL
1965 Volvo 122S
1986 Ford Capri 280 Brooklands

[rwmastel]

Jaap,

Hi.  I don't have an answer to why your car is slow to respond to the throttle, but mine is too.  I have a 230SL with a worn out engine (low compression, uses oil, and so on).  What state are your mechanical parts in?

I am working with a couple of our Members in the UK and Ireland to get a Pagoda event organized over there.  When that happens, you'll have to attend.  Maybe some kind and generous Member will let you drive his automatic transmission Pagoda and compare.  Of course, we would request that you take some nice pictures of the event, I saw your web site!

Thanks,

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[mdsalemi]

Folks,

Mine was a bit sluggish as well until Dr. Benz discovered improper vacuum advance.  So, as always, back to basics!  Make sure your timing is set correctly; ensure your vacuum advance is working, ensure it has no leaks.  Don't get me wrong--we're not going to win any acceleration contests--it isn't and never was a speedy car and not even a sports car--but when it is working per the book it isn't too bad.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[Cees Klumper]

Like Michael, I was going to suggest to check the basics, and ignition comes to mind.

Having said that, last Monday I drove the Pagoda of a colleague around the block and remarked that it was running on only 5 cylinders all the time. He had not noticed! I suggested he clean up or replace the spark plugs. Then I checked under the hood to find the main spark plug lead (the one from the coil to the distributor was cracked). To make a long story short the next day he fixed these things and told me the car ran like never before (surprise). I am sure that this is more extreme than what is going on with your car, but I note this just to point out that Pagodas are out there with all kinds of issues.

The idle should be around 800 RPM´s. Besides the ignition, I would check ALL of the basics like (CO) mixture, linkages, fuel flow and filter etc etc.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Benz Dr.]

A couple of things come to mind:

1) The throttle linkage has to be set up so that both throttle levers open at exactly the same time - injection pump and air contrl valve. If one opens before the other you will either get a rich or a lean condition depending on which opens first. This will cause poor off idle throttle response.
2) weak voltage:
different than throttle levers in that there tends to be a small stutter or miss but the throtle response is there - just slower than it should be. Bad wires, weak coil, carbon core coil wire and bad spark plugs are all things to look for. Spark plugs will be dry and black with only the very tips showing a light gray colour - it's low voltage. Car will have a rough idle as if it were cold even when fully warmed.
3)vacuum leak:
similar to throttle linkage except it's a bit longer in duration because it was present at the time of throttle movement. Small flat spot during gear changes and more pronounced than throttle sync.
4)Distributor problems:
Sticking flyweights, loose bearings, bad points and no vacuum movement. Car may atually start and run OK but not have good power curve. Response is generally flat and it may have a slight miss that appears at any engine speed.
5) Fuel and injection pump:
Different than all the others. This tends to just shut the engine off or it will slowly loose power and die. Tends to be very hard to start once warmed and may have some very flat spots during driving.
This can be futher separated into two distinct areas a) fuel delivery b) fuel injection
Fuel delivery:
All lines, filters, screens and electric fuel pump must be free of obstructions and fuel pressure/volume must be maintained at all times. A bad fuel pump or plugged lines will cause the engine to shut down or not restart until cooled.
Fuel injection pump:
I save this until last because it's the last thing I'd pull from your car if everything else checked out. Obvoiusly, a lot of diagnostics needs to be done first.
Simple fuel adjustment at the back of the pump may be all you need or the slide valve could be stuck in the warm or hot position. Either way you will have trouble with cold or hot running depending on which one you have. Also, fuel injectors and cold start valve may be dirty or leaking.

 All this sounds complicated or confusing? Well, it is but most people can do it. The symptoms are so similar between all these problems that it can fool the best of us. Anyone with basic tools, a few skills and some good advice can work through most of these things.

 It's why we're here, why your here and why I'm here.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[wildatheart]

quote:Originally posted by Benz Dr.

A couple of things come to mind:

Thanks Dr. Benz for such a wonderfully informative reply. I will work through your various suggestions, chasing those few tenths of a second!

Thanks again,

Jaap

1970 280SL
1965 Volvo 122S
1986 Ford Capri 280 Brooklands

[wildatheart]

quote:Originally posted by rwmastel

Jaap,

Hi.  I don't have an answer to why your car is slow to respond to the throttle, but mine is too.  I have a 230SL with a worn out engine (low compression, uses oil, and so on).  What state are your mechanical parts in?

I am working with a couple of our Members in the UK and Ireland to get a Pagoda event organized over there.  When that happens, you'll have to attend.  Maybe some kind and generous Member will let you drive his automatic transmission Pagoda and compare.  Of course, we would request that you take some nice pictures of the event, I saw your web site!

Thanks,

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

Hi Rodd,

I think my car is in pretty good shape so I am cautiously optimistic. Keep me posted on the UK event you mentioned; as for photographs, I don't usually like to mix business with pleasure but of course there's an exception to every rule..!

Jaap

1970 280SL
1971 BMW 2000 Touring
1965 Volvo 122S
1986 Ford Capri 280 Brooklands

[Benz Dr.]

Compression is HP. Low compression means lower HP.

  A high compression ( gasoline ) engine responds very quickly to throttle movement. Ever notice how snappy a new car is or when you get your engine rebuilt? This is when your engine has max compression and produces max power - everything else goes slowly down hill with age.

A simple compression test will tell you what that number is and if it's within the normal range. However, compression testers are not that dependable for finding leaks and a vaccum tester or leak down tester will give you better results.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org