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  #1  
Old 03-14-2019, 05:01 PM
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No power/acceleration 1987 300D? (SOLVED)

I just replaced my injector nozzles (re-balanced them myself), deleted my EGR, and replaced worn vacuum hoses/connections. I think some of my vacuum connections may still be a little loose though..



I know I still need to vacuum test all of the lines, however after doing all of this work, I have noticed a significant decrease in my power. Where should I start? Could deleting the EGR have negatively effected the turbo performance (I can't hear it as well as I could before)? Should I be looking at maybe a boost leak or clog in my exhaust? Any help is greatly appreciated!

Last edited by Ravenswift; 03-17-2019 at 04:44 PM. Reason: Solved
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  #2  
Old 03-14-2019, 05:46 PM
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Make sure your switchover valve is good and that you have the right hoses on the right nipples. Otherwise you will be lucky to get over 30mph. In my '81 300SD it is located on the firewall on the driver's side. One hose goes to the ALDA and prevents overboost of the turbo. Mine is shown near the right center of the pic and has a metal cube cover over it; the original '81 switchover valve did not have the metal cover.
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Old 03-14-2019, 05:50 PM
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I know ive got everything hooked up right, but didn't think about the switchover valve being bad..im hoping its not the alda itself...
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Old 03-14-2019, 09:09 PM
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The ‘87 300D has a line from the ALDA pressure signal to the transmission vacuum amplifier/BFS (blue flying saucer). If that line is leaking or the BFS itself is leaking, you won’t get a good signal to the ALDA.

Sixto
98 E320s sedan and wagon
02 C320 wagon
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Old 03-14-2019, 09:15 PM
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ill check it
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Old 03-14-2019, 09:21 PM
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just take the Alda off. I did on my 87 300d. Ran a lot better without it. Stupid emissions crap on a 32 year old car.
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  #7  
Old 03-15-2019, 07:58 AM
WTB: 94/95 E320 Wagon
 
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I also think you've got an issue with your ALDA boost signal (however I don't agree with deleting the ALDA). You could temporarily bypass the overload protection valve to make sure that is not blocking the signal. Check the manifold nipple for the boost signal, make sure that hasn't gotten plugged with soot.

Does the turbo spin free? I'd check that, and take a hard look at all the intake path from air filter to turbo. If all that checks out, maybe get a boost gauge to check the boost. Waste gate pressure hose get disturbed? That would simply disable the waste gate so you'd get full boost.

Exhaust plugged - hmmm, I'm not sure that could happen so quickly, but maybe worth checking it out.
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Old 03-15-2019, 06:15 PM
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I will have a look at the ALDA and UFO. I doubt the lines or nipples are blocked because i just cleaned all of that out really well.

I Haven't really looked at the turbo at all. I know nothing about the wastgate, where it is, what it is, or what it does so I dont even know where to start with that one.
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  #9  
Old 03-16-2019, 08:06 PM
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Okay, I bypassed the switchover valve and BOOM problem solved. Should I replace the existing one? or just leave it bypassed?
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  #10  
Old 03-16-2019, 09:00 PM
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smoke gets in your eyes
 
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It might just be clogged. Spray through the fittings with brake parts cleaner until you can blow through it. You might do the same with intake manifold nipple.

Check the contact on the manifold pressure switch. It shouldn’t be continuous to ground with the engine off.

Sixto
98 E320s sedan and wagon
02 C320 wagon
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  #11  
Old 03-17-2019, 05:40 AM
WTB: 94/95 E320 Wagon
 
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The engineers put it there for a good reason, to keep your pistons from melting. Fix it right.
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Old 03-17-2019, 09:04 AM
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Replace the switchover valve. It is cheap. Do it right. My original only lasted thirty years.
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Old 03-17-2019, 04:42 PM
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blew it out with some brake cleaner and it seems to be doing much better. not quite as good as it was bypassed so eventually I will replace it, but for now i think this problem is solved! Thanks to everyone! Big help!
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  #14  
Old 03-17-2019, 05:05 PM
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Wow. Pelican wants $109 for a switchover valve; do not remember paying the stealership nearly that much when I replaced mine. Do not blame you for re-using the original.


Intake Manifold Pressure Change-Over Valve
Part #: 001-540-86-97-MBZ
[ More Info ]


View in Catalog: Intake Manifold Pressure Change-Over Valve, Brand: Genuine Mercedes

This part fits your 1981 Mercedes-Benz 300SD Sedan


Brand Rating
$108.75
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  #15  
Old 03-17-2019, 05:45 PM
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thanks for the info!
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