Very little power - PeachParts Mercedes-Benz Forum

mahnu · #1 05-08-2006, 05:06 AM

Hi all:

I finally got my 350sl running and have replaced the following.
Plugs,points, cap, rotor, wires, coil, switchgear, fuel pump, fuel filter
All injectors were removed and cleaned. Compression is fine. Timing is set.
Engines idles fine and revs nicely.

I am noticing that the car does not have the power that I would expect out of an 8 cylinder.

The only item I have not played with is the idle adjuster.

Any ideas?

page62 · #2 05-08-2006, 09:43 AM

Quote:

Originally Posted by mahnu

Hi all:

I finally got my 350sl running and have replaced the following.
Plugs,points, cap, rotor, wires, coil, switchgear, fuel pump, fuel filter
All injectors were removed and cleaned. Compression is fine. Timing is set.
Engines idles fine and revs nicely.

I am noticing that the car does not have the power that I would expect out of an 8 cylinder.

The only item I have not played with is the idle adjuster.

Any ideas?

Can you be a little more specific about the power output? These cars aren't exactly "barn burners" but they generally have adequate power, considering their age...

tram · #3 05-08-2006, 02:06 PM

Check for a brake dragging or not releasing. Brake hoses and calipers are a common failure item on these and will SIGNIFICANTLY reduce power. I see this quite frequently.

coleyjf · #4 05-09-2006, 03:30 AM

Hi

Does the "kick-down" come in on full throttle (check the fuses) and possibly if it's REALLY lacking in power check that the engine isn't in "get you home" mode ( this can also be a fuse)

Otherwise just sit in your SL and SMILE

cheers

Jim

gerhuet · #5 05-09-2006, 07:11 AM

Quote:

Originally Posted by coleyjf

Hi

Does the "kick-down" come in on full throttle (check the fuses) and possibly if it's REALLY lacking in power check that the engine isn't in "get you home" mode ( this can also be a fuse)

Otherwise just sit in your SL and SMILE

cheers

Jim

Hey Jim. What's "get you home" mode ?

Gerry
Wexford

coleyjf · #6 05-09-2006, 08:27 AM

sorry should have said "Limp Home Mode" It's when the management system detetcts a major fail and drops the power to "limp home" Not sure of the technical stuff - someone will explain I'm sure. There are threads about it on this site.

Cheers

jim

page62 · #7 05-09-2006, 09:23 AM

I think a 350SL is a little too prehistoric to have a limp home mode.

From all the suggestions, I'd go with the dragging brake theory...

mahnu · #8 05-11-2006, 03:10 AM

All:

Thanks for the posts.

To be clearer on the power loss issue.
The car was sitting for over 14 years when I got it. A quick change of points got the car started. At that time, ( two months ago ), I was able to drive around the block a few times. Even when flooring it, the car did not go faster than 30 mph.

Now after changing many components and giving it a good tune up, I am reluctant to take it on the road until I am confident that it will make it home. I live on a hill and don't want to have to tow it into my driveway, which is also a hill. So, as far as my recent testing, it has been up and down the driveway. Again, I floor it and I barely get up my drive way.

I did remove all wheels to check for brake dragging. Not the problem.

Any more ideas?

Broxin · #9 05-11-2006, 07:58 AM

hmmmm. Some sort of clog in the exhaust? Cats?

page62 · #10 05-11-2006, 09:00 AM

Did you clean or replace the fuel strainer in the bottom of the gas tank?

Earlybird · #11 05-11-2006, 11:48 AM

Check your ignition advance systems. No advance= good running slug.

mahnu · #12 05-13-2006, 10:10 AM

Thanks for the replies.

Exhaust: There is no cat on this car. A bit loud, so I do not suspect clogging to be a problem.

Fuel strainer. Did not check. A real pain to remove the tank. I did, however, change the fuel filter and pump. Fuel pump presssure at the rail is fine.

Advance mechanism? What controls this? The diaphram at the distributor or the unit behind the glove box (ECU?)? At the distributor, the diaphram seems fine.

J

page62 · #13 05-13-2006, 07:27 PM

Quote:

Originally Posted by mahnu

Fuel strainer. Did not check. A real pain to remove the tank. I did, however, change the fuel filter and pump. Fuel pump presssure at the rail is fine.

J

No need to remove the tank. But you will need to drain it. The strainer simply unscrews from the bottom.

But check your timing advance first. It's easy. Hook up a timing light, look for the timing mark at idle. Then rev your engine -- the mark should move from the point where it started, and then subside back as the rpm decreases. If it stays in the same place, you got no advance.

Bondavi · #14 05-13-2006, 08:55 PM

These cars used plastic vacuum lines which most certainly get brittle and crack with age. A good thing to check if you have vacuum problems is getting no advance. A timing light will tell you this quite easily.

Check the condition of your vacuum lines around the intake manifold and the color coded rubber tubes as well. You said the car has been sitting....most certainly this is the place to look.

Keep us posted!

tram · #15 05-13-2006, 09:10 PM

Take off the air cleaner. Have someone sit in the car and mash the accellerator to the floor. Is the linkage moving as it should? Are the ball shaped bushings on either end of the big rod that goes from the firewall to the engine by the intake in good shape? Or, is the linkage just flopping around? Manually move the linkage at the end of the big rod by the intake and see if it is going all the way to full throttle stop. Those plastic ball bushings are a high failure item, and might have a lot to do with it. It might just be that simple. They're still available through Benz, and they're dirt cheap.