Turbo Dead - Page 3 - PeachParts Mercedes-Benz Forum

sixto · #31 10-10-2010, 10:59 PM

Quote:

Originally Posted by vstech

when I pulled the airfilter box I noticed the cold air intake has a throttle of sorts... what is it, and how does it open and close? could it be closing in the OP's car limiting the intake of air for the turbo to pressureize?

That's a somewhat mechanical airflow meter. Airflow pushes the flap which registers as an electrical signal for the EDS. You can ditch it if you've disabled EGR and ARV, but it's part of the structural attachment of the air cleaner.

Sixto
87 300D

vstech · #32 10-11-2010, 08:17 AM

I figured it was some type of speed density meter like my vette, but could not imagine what it measured the air for...
so in the O.P.'s case, if that mouse nest that was in there, has damaged the flap's ability to move, it could indeed be causing the problem with turbo flow.

winmutt · #33 10-11-2010, 08:40 AM

Quote:

Originally Posted by vstech

I figured it was some type of speed density meter like my vette, but could not imagine what it measured the air for...
so in the O.P.'s case, if that mouse nest that was in there, has damaged the flap's ability to move, it could indeed be causing the problem with turbo flow.

As long as the engine is turning and it revs the turbo sill spool more than his did. 0.45psi?

vstech · #34 10-11-2010, 08:46 AM

.45 could be from a stuck closed airmeeter box too though. if he's not getting enough air to compress in the turbo, it'll certainly limit boost.
you could rig a probe into the turbo intake tube, and see if it's operating in a vacuum, or at atmo. heck, I'd just pull the air cleaner, and jam a pipe in there to hold the blade open, and see if it helps!
or temporarily pull the intake tubing off the turbo entirely and see if the car performs better or not.

LoosBenz · #35 10-11-2010, 06:12 PM

Well, I don't yet know if it will solve ALL of my problems, but I feel pretty sure my EGR valve is stuck open. I pulled the crossover and started the engine. A steady puff of exhaust wafted up from the port from the turbo while idling and a black poof when I stepped hard on the accelerator. This is with the vacuum line disconnected from the EGR.
Is my logic sound here?

LoosBenz · #36 10-12-2010, 08:32 PM

Fabbed a block plate for the EGR port and installed it this afternoon. Whoa! What a difference! This thing really moves!

Thanks all!
Louis

vstech · #37 10-12-2010, 08:41 PM

so... the turbo could not build pressure, because the intake was stealing it all... and exhaust was dumping into the intake mixture really killing the mix...
wow.
of course, the FIRST thing I do on a car I drive is block off the EGR, so I would not have ever seen the issues you had...
SOOO glad you found the problem though! enjoy it!

LoosBenz · #38 10-12-2010, 08:56 PM

Quote:

Originally Posted by vstech

so... the turbo could not build pressure, because the intake was stealing it all... and exhaust was dumping into the intake mixture really killing the mix...
wow.
of course, the FIRST thing I do on a car I drive is block off the EGR, so I would not have ever seen the issues you had...
SOOO glad you found the problem though! enjoy it!

Thanks! Yeah, kind of a vicious cycle, huh. Probably one of the few situations where pulling the ALDA actually made it worse because of all the extra soot etc. going into the intake. Quite the learning experience.

winmutt · #39 10-12-2010, 09:18 PM

Interesting I would have thought the the EGR was too small.

LoosBenz · #40 10-12-2010, 10:35 PM

Quote:

Originally Posted by winmutt

Interesting I would have thought the the EGR was too small.

That's part of the reason I didn't pay more attention to it. I haven't put a gauge on it yet to get a pressure reading, but it feels much more like I would expect. At its worst, I was building up speed getting a head start to clear some of the hills around here and still end up going less than 20mph by the time I reached the top. Now I'm going up hills that I didn't dare try in that condition and making 70+ mph using maybe 1/2 pedal travel.
If I floor it under boost, I still get significant smoke, but its not the dark black smokescreen it was putting out before. Its much less and much lighter and the car actually accelerates instead of bogging.
The transmission is also much happier. My only complaint is that it doesn't kickdown as much as I would like. It also still has a harsh shift if I lift off of the accelerator just before it is about to upshift, but I can live with that. It shifts very well, otherwise.
The crossover and intake are really gooked up. If I go back and clean them out, it'll probably run even better.
It's sooo nice having the power back!!

don b · #41 10-17-2010, 07:31 PM

i have a 85 300td california, can anyone show me a pic of the egr and how it comes off and how to plug it. i have the vac line off and plugged with a bb but from what i hear i need to take it off and plug the hole. my car is doing the exaxt same thing. fas ton the flat and 40 up hills. i hooked up a boost gage and i have 3 lbs of boost at 4k rpm. hooked up a manual boost controller and no change. i'm loosing pressure somewhere, i don't think the turbo is spooling up because of this. thanks don

sixto · #42 10-17-2010, 07:57 PM

This thread should help - http://www.peachparts.com/shopforum/showthread.php?t=265498

Might not be obvious that the above thread references this thread - http://www.peachparts.com/shopforum/showthread.php?t=264272

The EGR valve used to be where now you see an oblong blocking plate just aft of where the upper radiator hose attaches to the engine.

If you're lazy to block the other end, slip a blocking plate between the EGR valve and manifold but leave the EGR valve in place.

Sixto
87 300D

don b · #43 10-18-2010, 12:04 AM

thanks i'll try to plug it and get back at ya to see if it gave me more boost! thanks