Car drives without symptoms, then severe hesitation bordering on stalling. exhaust shows either unburned diesel (White) or blue oil smoke--my experience methinks air starvation. When you think you have to pull over, it corrects itself, and drives as normal. This may occur infrequently or frequently. Fuel is fine, starts up fine, even in cold weather, Idles well. My Indy says air sensor within the air cleaner or one of the flaps in the air duct system malfunctioning. Any ideas? thanks all...

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71 220D 169K wrecked
83 240D 118K sweet 4 speed
91 350SDL (one of the 60% good engines) 156K
84 300d (loaner to my sister) 189K
79 300SD (partswagen)
86 420SEL partswagen
70 220d (partswagen)
68 280s GASSER!!! under construction now
85 300sd 310K miles winter beater car retired
93 300d 2.5 turbo 168K wife's car
83 280SL euro 5 speed 155K
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What's the status of the air filter? Are you getting turbo boost? What's the condition of fuel filters? Did you do any maintenance recently? Have you started getting diesel at a different place? What's your coolant level?

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92 300D 2.5L OM602 OBK #59

all items mentioned ruled out: air cleaner, fuel filters, boost no fuel issues.

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71 220D 169K wrecked
83 240D 118K sweet 4 speed
91 350SDL (one of the 60% good engines) 156K
84 300d (loaner to my sister) 189K
79 300SD (partswagen)
86 420SEL partswagen
70 220d (partswagen)
68 280s GASSER!!! under construction now
85 300sd 310K miles winter beater car retired
93 300d 2.5 turbo 168K wife's car
83 280SL euro 5 speed 155K
69 250S newest project 54K

The computer only controls boost and idle. So air sensor within the air cleaner is a no go. flap in the air duct system. You can disconnect it. It fails in the open position. Works with the EGR system. Maybe your crossover tube is crudded up.

Maybe you've got a bad.. I don't dare say it.

Can you give more history on the problem.

The reason I mention the other stuff filters/fuel/ and such is it's a diesel. No spark, you need only air/fuel/compression. Computer only cuts boost if parameters aren't met and controls the idle. I don't see how you're not getting air. Unless your cross over pipe is clogged but then it would always run like crap (always starved for air). That leaves fuel or compression. You say fuel's not an issue. That leaves compression.

Definitely need more history info. What's been recently done? Just appeared out of the blue? You might want to do a compression test. Has it been run on WVO?

Attached is the pressure control flap. Works in connection with EGR valve. Is normally in the open position. You can disconnect the vac line that goes to it to see if it's causing the problem. You will lose boost.

Attached Thumbnails

       

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92 300D 2.5L OM602 OBK #59

severe fuel filter plugging up will cause similar symptoms. how have you eliminated fuel filters as the cause? did you replace them?

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I'll be trying that actuator operation tomorrow. Thanks for the info diagrams

__________________
71 220D 169K wrecked
83 240D 118K sweet 4 speed
91 350SDL (one of the 60% good engines) 156K
84 300d (loaner to my sister) 189K
79 300SD (partswagen)
86 420SEL partswagen
70 220d (partswagen)
68 280s GASSER!!! under construction now
85 300sd 310K miles winter beater car retired
93 300d 2.5 turbo 168K wife's car
83 280SL euro 5 speed 155K
69 250S newest project 54K