Throttle/alda/IP adj. from scratch? - PeachParts Mercedes-Benz Forum

Wallknight · #1 09-21-2002, 06:20 PM

Hello friends!
My 300D is driving me nuts still. A while back, I did a little tweaking with the ALDA, and ever since, no matter how far I turn it down (losing all the power off the line), it still smokes like crazy at 65mph. Now that I finally got a new temp. sensor, at least I know its not overheating.

Here's my question.

How would one go about completely resetting the throttle? I"m talking linkages, ALDA, IP timing, whatever. Assuming all the pieces were on the floor totally needing to be reset, where do I start?

The previous owner made adjs. I know; the alda cap is gone. So I think everything is out of whack.

Also, how do I make an IP drip method tool?
Thanks!

psfred · #2 09-22-2002, 01:02 PM

To make the IP tool, you need a correct flare nut for the pressure valve holder and a correct sized piece of tubing with a flare on it. You can get the nut at a good plumbing or auto supply place (or Bosch service, for that matter) and can probably get someone to flare a bit of tubing for you. Bend it over almost 180 degress and saw it off at a 45 degree angle so that you have a point for the fuel to run off.

Or you can just buy it, it isn't that expensive, I dont' think. We borrow one when we need it.

The ALDA needs to be set on a test bench whilst attached to the IP -- not doable at home.

Smoke a high speed is usually late injection timing, not an ALDA adjustment, or max fuel delivery set too high on the pump (internal, I think). I would check the chain for stretch, replace if necessary, then set IP timing. After that, if the ALDA is still good, set for proper power, you will never get there if the timing is off.

Peter

Wallknight · #3 09-23-2002, 06:22 PM

Thanks psfred; I'll make the tool and give it a whirl tomorrow. I"ll let you know how it goes.

Wallknight · #4 09-30-2002, 08:30 PM

Ok, finally got the IP somewhat timed. Its at 24. Now it smokes a little more at high RPM, but its a smooth and constant black smoke, unlike the prior huge puffs. NOw, as I read other threads, it seems that if I keep retarding the timing (I think it was around 15btdc prior) it should take care of the rest. Is this correct?

Also, since I had a little less power than I wanted, I ccw'ed the ALDA 1/2. This seemsed to actually REDUCE the smoke.

SHould I try for 26 degrees, or just be happy and move on?

psfred · #5 09-30-2002, 09:22 PM

Paul:

Much easier with the correct tools, eh?

24 BTDC is exactly what you want. The black smoke at high speed is a result of too much fuel -- you did the correct thing with the ALDA to reduce it. A bit more may take care of it. Should give you the best hp and fuel consumption, too.

However, you will probably not be able to get very low smoke and good power unless your valves are in good shape and the chain is the correct length. Check it by lining up the marks on the cam with the mark on the front cam tower, then checking the crank pointer. More than 8 degrees and it need to be replaced. If you do, guess what, you've got to re-set the injection timing......!

Otherwise, check to make sure the boost lines are OK and that the banjo bolt on the rear of the manifold is clear, and that your valves are correctly adjusted -- sloppy or tight valves will make you smoke like crazy from low compression, especially at speed.

Peter

Wallknight · #6 09-30-2002, 09:30 PM

Correct tools? YOu dont even want to know what I built!!

As for the Alda, doesnt Counterclockwise usually increase smoke at high speed?

I'll fiddle with that and check the chain, but I think I'm finallly getting close.
Thanks Peter,
Paul

Wallknight · #7 10-03-2002, 09:09 AM

Ok, here is the latest.

I went home and gave the ALDA another 3/4 Counter CW. Viola! All the smoke at low speed disappeared, lots of low end torgue appeared. I was happy.

Took it out on the highway yesterday, hit 65 up a hill, still no smoke! I was thrilled. So I let out a victorious shout. Half way through the shout, it hit 70mph, and a big old puff of black smoke came back. @##%@#@$^

so, I must be pretty close to getting it right. I'm not touching anything yet till I'm sure what to do.

Do I:

1. Adjust the ALDA again? if so, which way?
2. Readjust IP timing? Again, which way (its still at 24)
3. Hunt down some Purge and clean out the injectors?
4. Be happy I'm able to drive it at all and leave it alone!
Thanks again,

gsxr · #8 10-03-2002, 06:22 PM

1- Turning the ALDA CCW richens the mixture and normally increases smoke, CW leans it and reduces smoke.

2- You can use the IP lock tool to set your timing instead of the annoying and messy (IMO) drip method. The tool is ~$25 from your dealer.

3- Purge never hurts.

4- Don't start fretting just yet. One single plume of smoke does NOT indicate a problem. If it is smoking all the time under load, or over a certain RPM, you have an adjustment problem. If it's fine most of the time but you get a cloud now and then, relax, it's probably just carbon burning its way out of the prechambers etc... that's a good thing, don't worry about it.

5- Advancing the timing a smidge (1.0 or 1.5 degrees) may improve MPG a hair, might not. Depends how much you enjoy rotating that pump!

Regards,

psfred · #9 10-03-2002, 07:45 PM

Take it for a trip. Get some diesel purge or Redling, dump it in the tank, check oil, fill tank, and drive for a while. Several hours at 70 mph would be great.

Puffs of smoke indicate something like the crap in the exhaust catching fire, a nozzle sticking, or etc, not a timing problem. Your timing is fine, sounds like you have the ALDA about right, but if you were overfueling (black smoke) the prechambers are full of soot, the turbo is full of soot, and the nozzles are carbon fouled. A nice drive will fix all of that.

My Volvo had a bad IP when I got it, also a bad turbo. Made too much smoke (still does, that is another story), so when I drove it around down a lot, the exhaust got full. A full throttle run would always produce an inky cloud.

Took it to my sisters, and on the way home one time, I noticed what looked like a dropped cigarette on the road behind me -- this was after topping the hill on I64 going west out of Lousiville, KY.

No one in the car was smoking, no one in front... next hill at the crest as the cruise control lifts the pedal, more sparks-- blew burning chucks of carbon out all the way home! Actually burned though the resonator, ended up with a new exhaust system. The carbon was at least 1/4" thick the entire length of the exhaust, thicker in the mufflers. I'm lucky it didn't really catch fire!

Peter

Fisherman · #10 10-03-2002, 08:39 PM

Just a thought but I noted that in your driving frenzy you were heading up a hill and no smke, then when you hit 70 a puff came out...
Could you have been backing off on the throttle i.e. just over the crest of the hill? If this was when you got the puff I would say "No Worries". I think almost every diesel will puff a little when you go from full or near full throttle to no throttle after cresting a hill.

I know it's kind of a shot in the dark but I'm hoping you got everything perfect the first time...;-)

Wallknight · #11 10-05-2002, 08:52 PM

Fisherman,
Hmm. I may have backed off... But its more than just a puff. It starts smoking, then if I get off, it still smokes a bit, then runs fine again. Someone has described acceleration in his car as like a locomotive puffing up a hill. That's a decent description.

Peter,
YOu may be onto something, though you've also got me scared of fire! i dont do much high-speed driving around here (nor the prior owner). mostly just a lot of hills and lights and 40mph signs. Its running absolutely fantastic now at those speeds.

I tried to find some redline or purge at the pepboys. no luck. no one else has it either. So i got a bottle of Lucas Inj. Cleaner. We'll see.

psfred · #12 10-05-2002, 09:08 PM

Dollar to a doughnut your injectors are carboned up. Injector cleaner and a nice trip will fix that up nicely.

Peter