I'm about out of options-loss of power - PeachParts Mercedes-Benz Forum

muleears · #1 07-25-2007, 12:57 PM

Recently the performance of my 124 has deteriorated from <12 sec. 0-60 to 24 sec. 0-60. It also smokes a lot now. I have tried an Italian tune up but it won't accelerate fast enough to do any good, and when I do the smoke is horrendous. It seems to shift at the right points. When floored it will shift @4500rpm. It also lunges when it shifts. It just takes a long time to reach the shift point. It even smokes at mild acceleration, which it didn't do before.

Here is what I have done so far:

Changed both fuel and the air filter
adjusted ALDA
Swapped supply/return lines

Do you think the following will help:
Diesel purge
Clean tank strainer
Injector clean/pop test

What else could it be? Bad ALDA, plugged cat? Any suggestions appreciated.

Brian Carlton · #2 07-25-2007, 01:40 PM

At 24 seconds, you've got a serious problem.

If the fuel filters are good and the tank screen is not plugged solid (unlikely), then the problem is more complicated.

It only takes five minutes to remove the ALDA and take it for a test drive. See what you get without the ALDA limitation on fuel.

The smoke concerns me and the lack of fuel should not cause any smoke..........just reduced power.

What's the color of the smoke? Does it smoke at idle? If so, what's the prevailing smell of the smoke..........fuel.........or oil?

BTW, this wouldn't be the first time the cat was plugged on such a vehicle. In fact, I think the '87 suffers partially from that problem. Still doesn't explain the smoke...........

tobybul · #3 07-25-2007, 01:41 PM

Lets try the simple stuff first... do adjustments as a last resort.

Since theres an alda, I'm assuming theres a changeover (also called overboost protection) valve. On a 123, its behind the brake booster on the firewall. take it out and clean it. Take note of the connections. I use brake clean to push the gunk out thru the openings. Reinstall. Also, it would help to clean the banjo bolts on each end of the alda line between the manifold and the alda. test drive.

C Sean Watts · #4 07-25-2007, 01:42 PM

you change the tank sieve, try and flush then blow out the fuel line and have someone watch (or lay newspapers under the the line) and see if anything comes out. The PO of mine had to have this done and his indy listed it on the receipt.

ConnClark · #5 07-25-2007, 03:54 PM

If you have black smoke its injector problems, lack of air, excessive EGR, or bad injection timing.

Do you have a boost gauge? If so what is your boost at?

muleears · #6 07-25-2007, 04:13 PM

Smoke is black and plenty of it, smells like fuel.

I will clean the overboost, remove the alda and post findings.

Acceleration 0-15 seems to be normal, from there on its a dog. Don't have a boost gauge and don't have banjo's on the 603 but I have cleaned the vac. hoses.

Won't swapping the supply/return tell me if it is the tank screen?

Thanks for the help so far, I hope to make some headway. Hopefully I'll repost in an hour or so.

Brian Carlton · #7 07-25-2007, 04:17 PM

Quote:

Originally Posted by muleears

Smoke is black and plenty of it, smells like fuel.

I will clean the overboost, remove the alda and post findings.

That's valuable information.

You can forget about the overboost, the ALDA, and anything else related to boost. You've got the fuel..........it's telling you that in the exhaust.

The problem is lack of air..............what's restricting your airflow? Could be the air filter..........or the cat...........or the turbo is not spinning.

Check for anything that won't let the engine breathe.

dieseldiehard · #8 07-25-2007, 04:17 PM

I saw a plugged CAT cause the same symptoms

muleears · #9 07-25-2007, 05:14 PM

Since last post I have cleaned the overboost switch with no results. I also did a one can diesel purge, it still smoked even during the purge and also showed me that the tank screen isn't the problem. I guess now I have to concentrate on the cat and the turbo. I have no idea how to check the cat or the turbo, this may be a job for my indy. After all the car does have 325K on the original turbo. Trap was replaced at 185K. Thanks again for all the advice, any more?

#10 07-25-2007, 05:18 PM

Check the air filter housing and its snorkel tube for restrictions like a plastic bag or leaves.

Wolfsburg · #11 07-25-2007, 09:41 PM

You may an air problem...There is a bolt in the manifold near front of engine, on passenger side, remove it and try your engine...Do a search under my name and you will find ideas for "no power". I had a plugged Cat, and had a straight pipe installed then. A lot of black smoke/ carbon will come spitting out of the hole. Good Luck.

dieseldiehard · #12 07-26-2007, 12:59 AM

Quote:

Originally Posted by muleears

Since last post I have cleaned the overboost switch with no results. I also did a one can diesel purge, it still smoked even during the purge and also showed me that the tank screen isn't the problem. I guess now I have to concentrate on the cat and the turbo. I have no idea how to check the cat or the turbo, this may be a job for my indy. After all the car does have 325K on the original turbo. Trap was replaced at 185K. Thanks again for all the advice, any more?

What's that you say? The Trap was replaced with another Trap?
Or wasn't it replaced with the CAT. The CAT is located under the car after the downpipe straightens out, under the floorboard, the TRAP is located between the exhaust manifold and the Turbo inlet, it looks like a large football shaped thing.

Either one would definitely be suspect at this many miles since replacement they may have plugged up again. I remember Wolfsburg's problem was just that. A factory test calls for hooking a pressure meter at that port in the front of the exhaust manifold. The meters are pretty hard to find and expensive so most mechanics just remove the plug and see if it helps a lot knowing if it does then the trap is plugged. I had one so plugged the car WOULD NOT EVEN RUN!

The dealer can check records and see what was done under the "Open Campaign" for trap replacements. You may have another factory recall available.

tjohn · #13 07-26-2007, 08:55 AM

Is it possible to just unbolt the exhaust at down pipe on these cars? If the 124 is like the 126 the exhaust is just bolted together in various sections. If there's one upstream of the cat, couldn't he just unbolt it and test???

muleears · #14 07-26-2007, 09:25 AM

I should have been more specific, the trap was replaced with a cat. The car seemed to run a little better this morning, could the DP have helped clear the cat?

I will find and remove the bolt this evening and report back with the results.

Thanks for all the help.

vstech · #15 07-26-2007, 11:14 AM

hmm, you may want to edit your sig. most 46year old women, don't appreciate their age being broadcast on the net....
DP could certainly improve a dirty/plugged cat. but it would take A LOT... maybe 4 or 5 cans... since you have an improvement, be sure and pull the exhaust to verify the problem is the cat.

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