I have been trying to fix this issue for a month now. When driving the car the power will go up and down with no pattern to it. Up hill, downhill, turning, straight, UGH! It will start to accelerate properly then it will be a dog, but sometimes it works the way it should. Then all of the sudden back to being a dog. When it's running properly it runs great. I don't get it! I'm pulling my hair out!

Items I've addressed to try and fix this issue:
-Fuel tank removed, cleaned and new tank screen.
-New fuel filters
-New injectors
-Check vent line for blockage
-Blocked off EGR
-Checked tranny fluid
-Valve adjustment (double checked it)
-Cleaned the banjo bolt


I've been through a few tanks of diesel from different places, still does it. Could the wastegate be an issue? I have a used one sitting around I could swap. What other things can it be!

Thanks in advance

Put a pressure gauge on the manifold, that will tell you if there is a variation in turbo operation.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Where is the best place to tap in?

Line from manifold to overboost protection switch is usually easy to tap into.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Sounds a lot like a problem with the manifold pressure signal getting to the ALDA, or maybe the ALDA failing in a strange way (but I've never heard of one failing to cause a condition like yours).

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

I think you guys are onto something because I unplugged the wire going to the pressure switch on the manifold (see picture) and it stopped doing it.

So I'm wondering if it's the switch or the switch over valve? If I unplugged the pressure switch wouldn't that take out the whole overboost protection system?

Thanks guys, we are realllllllll close!!!!!

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Your waste gate hose is hosed. $2 5 minute fix.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I'll replace tomorrow! How does the wastegate hose effect the intake pressure switch?