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And suddenly.... BOOST

743 views 7 replies 5 participants last post by  sphinxrider 
#1 ·
Today I had the strangest experience in my
300SDL.

For about a year I've been driving my car as if it has no power. Now mind you it didn't seem DOWN on power, just not particularly quick, kind of "doggy" and so I drove her like that. No big deal. I was thinking it was normal.

Today I was driving, the engine fully warmed up, and as I start to ascend one of the big hills in my area the car sort of, dunno, found a "second wind" and out of nowhere the car just climbed the hill with more oomph behind it than it had anytime in the past.

I thought this was a fluke and instead of going home I went for a spirited drive... nothing crazy, just put my foot in it more than usual. Very mild "Italian tune up".

It wasn't my imagination, the car definitely has more power now, like the turbo is actually working!

I'm not complaining by the way, but I am very curious to know about any theories you guys may have.

I did run some additives in the past but nothing in the current tank though.

Did I finally blow out all of the cobwebs or something?

The car had sat about 7 years before I started driving it.
 
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#4 ·
Probably a blockage in the ALDA line got dislodged. That pressure "signal" has to go through some really small vacuum lines, and through at least one switchover valve, all of which can get blocked.

Clean / replace all those lines and the car will run much better. You might find the transmission shifts better too.

-J
 
#8 ·
I did a diesel purge the same time I started driving the car about a year ago.

Not sure what you mean? Just trace the "vacuum" lines. Start at the intake, follow it to the connection to the small hard line, through the black cover tube thing, over to the overboost protection solenoid, back to the ALDA on the injection pump, then back again to the trans vacuum modulator near the ABS unit. Be sure all the lines are clear of blockages, and don't leak.

The overboost protection solenoid should pass pressure normally. To check it turn the ignition on, unplug the single wire going to the 15 PSI switch on the intake manifold, and touch it to ground. The solenoid should click, and block pressure at the out port.

-J
Cool ! Thanks!
 
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