'87 300TD poor performance returns - Page 4 - PeachParts Mercedes-Benz Forum

TonyD · #46 01-04-2005, 07:07 PM

Thanks! The ALDA adjustment is one of the next things on my list for the 300SD. When I turn left at an intersection, I have to floor it to get it to move, and then the turbo spools up mid-turn and it's a wild ride!

dieseldiehard · #47 01-04-2005, 07:28 PM

The wild ride will get wilder if the ALDA is adjusted out, the pre-85 300D/TD did not have any technique of moderating acceleration as the turbo spools up, unlike the '85 diesels have.
You may need to learn to modulate your accelerator foot as the engine winds up, its something my wife finally learned to some degree, on her '83 300D but getting to this point took some teaching.
Come to think of it, she's driving my '87 300D turbo lately, and it has full acceleration all the time as soon as you hit the pedal, try driving one of them or an '87 SDL and you'll want to trade the '82 300D in. Oh, By golly, I hope she doesn't forget how to drive the '83

dieseldiehard · #48 01-04-2005, 07:31 PM

two shims usually work fine, if the ALDA is near factory specs.
I have no patience of ripping at the cap, its tough plastic and I hate getting my fingers cut up to, so the last time I messed with an ALDA I tore the metal cover off using diagonal wire cutters (carefully) but I recommend the shim approach first. Two shims is all Gus recommends else you may wind up with a smoking exhaust and fuel economy drops too, don't forget!

TonyD · #49 01-05-2005, 06:16 AM

You mean like when I had my 440 Six Pack Dodge 20 years ago and the front and rear carbs kicked in? Gotcha.

Seriously, I figure if I don't have to floorboard it just to get off the line, I won't have such a jarring transition from no boost to full boost.

WANT '71 280SEL · #50 01-05-2005, 08:28 AM

I drive a lot of time with my pedal to the floor on the SDL, is this normal? I don't usually go past the kickdown when accelerating, but I find it might even be a tad slower than my 116...
I plan to change both fuel filters then adjust the ALDA. Does adjusting the ALDA affect boost?
Thanks
David

#51 01-05-2005, 06:23 PM

I had to floor mine to get her going before ALDA adjustment. Since adjusting the ALDA, my mileage is about 21 city, 32 highway. Anybody know why my city mileage is so poor? Did I turn the screw out too far? I notice a lot of smoke at night in the headlights of cars behind me when I floor it. Otherwise, no smoke.

The car accelerates very well now. I'd love to get some better city mileage though. I drove to New York and back doing 80+ the whole way and got 31mpg.

Lukejt

gsxr · #52 01-05-2005, 08:34 PM

Quote:

Originally Posted by WANT '71 280SEL

I drive a lot of time with my pedal to the floor on the SDL, is this normal? I don't usually go past the kickdown when accelerating, but I find it might even be a tad slower than my 116...
I plan to change both fuel filters then adjust the ALDA. Does adjusting the ALDA affect boost?
Thanks
David

You have a classic case of needing to adjust the ALDA. The SDL should only require half throttle to get spirited acceleration from a dead stop. It should be noticeably quicker than your 116 diesel. Adjusting the ALDA can affect boost if the current setting is lean, you'll get more boost (to the wastegate limit of ~12psi) with the fuel turned up, and - oddly enough - you may get better MPG as well.

gsxr · #53 01-05-2005, 08:36 PM

Quote:

Originally Posted by Lukejt

I had to floor mine to get her going before ALDA adjustment. Since adjusting the ALDA, my mileage is about 21 city, 32 highway. Anybody know why my city mileage is so poor? Did I turn the screw out too far? I notice a lot of smoke at night in the headlights of cars behind me when I floor it. Otherwise, no smoke.

The car accelerates very well now. I'd love to get some better city mileage though. I drove to New York and back doing 80+ the whole way and got 31mpg.

Lukejt

If the car is getting 30-32mpg on the highway, your low city MPG is probably due to a lead foot, and/or poor quality fuel. It's also possible you adjusted the ALDA a bit too rich. You can turn it down a bit as long as there's no power loss. Ignore smoke in headlights, even a perfectly tuned engine will do that. Look for smoke in sunlight instead, it should be just a wisp, not a huge cloud, after a number of full throttle runs. If you drive lightly most of the time and then floor it, you'll *always* get a cloud of smoke. That's normal.

#54 01-06-2005, 08:09 AM

Lead foot.....ME?

LOL

Still getting much better mileage than any other vehicle I own.

Lukejt

WANT '71 280SEL · #55 01-06-2005, 09:26 AM

GSXR, does the intake have to be off to adjust the ALDA? I looked at my ALDA and it seemed impossible to adjust, (if the screw is on top of course). Where can I adjust it? Do I need to measure boost before or after to do it correctly?
Thanks
David

P.S.
My last calculation showed me getting 14.9mpg and 50% was highway... I have a thread regarding that however. Sorry to hijack.

gsxr · #56 01-06-2005, 10:04 AM

Quote:

Originally Posted by WANT '71 280SEL

GSXR, does the intake have to be off to adjust the ALDA? I looked at my ALDA and it seemed impossible to adjust, (if the screw is on top of course). Where can I adjust it? Do I need to measure boost before or after to do it correctly?
Thanks
David

P.S.
My last calculation showed me getting 14.9mpg and 50% was highway... I have a thread regarding that however. Sorry to hijack.

David,

1) I assume you are referring to your 300 SDL.

2) You don't need to remove the intake manifold, although if the gasket is leaking, and/or you need to change glow plugs, it makes it easier to do all that at the same time. To remove the ALDA for adjustment with the manifold in place, follow the pictorial at this link.

3) No need to measure boost unless you want to for grins. Proper ALDA adjustment is pretty much a seat of the pants thing, based on off-idle power delivery, and looking for excess smoke leaving a stop.

4) Yes, it's the screw on top of the ALDA - search the forum for more info on this.

5) If you're getting 15mpg, either your odometer is intermittent (more common than you'd think!), or you have a fuel leak. I'd be very surprised if it wasn't one of those two things.

msyoder · #57 01-24-2005, 09:42 PM

Hey,

Finally got a chance to report back after my Indy took a swing at my boost problem while he was changing my vacuum pump.

First thing he did was change the air filter -- how embarrassing. I was assuming it was clean by inspection, based on my experience with tractors.

This made a big difference and now he reports that my boost is up to 8psi. Haven't had a chance to verify the boost myself yet, but the car clearly has more power on hills. I'm still slow off the line in my acceleration tests.

He reported that the waste gate was slightly warped and not closing completely and that the compressor fins were worn and less efficient than when they were new. In the end he said that this was probably a good thing with an engine this age it would last much longer with only 8psi of pressure.

Couldn't realy argue with that, but would like to revisit the ALDA adjustment and see if it makes a more useful difference now that the air flow is unrestricted.

Thanks,