I have an 84 300D Calif emissions. Got to wondering just how much boost I was getting so I put a gauge on it and went for a drive. Barely got anything, only 2 to 3 psi. I was originally between the overboost protection device and the ALDA. Thought it might be the overboost device so I went to the hose off the back of the intake manifold and got the same numbers. Undid the banjo bolt and made sure it was clean as well as the hose. No change. I then undid and removed the U-shaped tube that feeds the inlet of the turbocharger. Very audible turbine whine but only a very slight increase in pressure, not more than 1 psi and probably less.

This slight increase seems to indicate its not a wastegate issue. I can't find a leak in the intake or exhaust manifolds.

Any ideas? The manual says boost should be about 0.75 bar or around 11 psi. Bearing drag? (I recently switched to Delvac 1 but performance has been consistent before and after the change except for better gas mileage) General crap?

Boost will often not get much above 3-4 psi unless the pedal is to the floor (car under full load), rpm above 4000. If the EGR or the wastegate (or the pressure tube to it) are are hanging open pressure may never get much above a couple of psi.

Marshall

Record the 0-62 mph acceleration time. Should be 14 sec. If it's close (within a sec), then your boost is about right. If the acceleartion time is 3-4 seconds longer then you have NO fuel enrichment and without fuel enrichment, boost WILL be very low.

Most low boost situations are NOT caused by bad turbos although they can be bad.

Marshall

Thanks for the reply! I'll start with the EGR valve (its easier to get to) I had the engine rev'ed pretty hard but I'm not sure of the RPM due to lack of a working Tach.

Overlapping replies, so I didn't see your second until after I had submitted mine.

I'll do the acceleration check. It sounds like from your second that I need to see if the ALDA functioning as well, assuming an 18 second or so time to 62. (hope my speedometer is right!) I know the line to it is carrying what little boost there is but I have not checked the ALDA itself for leaks or function.

ALDA problems are FAR, FAR more common than turbo problems.

Marshall

0-62 acceleration time for a perfect 123.130 (normally aspirated 300D) is 19 sec. That's what you'll get from an otherwise perfect 300Dturbo when there is NO fuel enrichment from the ALDA or NO turbo boost reaching the ALDA.

Full boost requires fuel enrichment, if there ios no fuel enrichment there will be insufficient heat to generate sufficient boost.

Marshall

NC AERO,
My CA car was around 7-8 psi when I put the guage on. I would double check for manifold leaks. Start the car cold and spray water next to the valve cover between the manifolds. Then watch your exhaust. White smoke=leaky gaskets. When I first started I found that I had leaks in numerous places. Catalyst was leaking, manifold gasket was leaking among other things.
Check out this link.....................

emissions swap...part one

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

Unless you place a 'load' on these engines, you can't accurately determine how much turbo boost you're getting.

Run the boost gauge into the cabin, go find a long hill and hammer down at 45-50 mph. Boost should max at .9 BAR (13.05 PSI) somewhere between 2200 rpm and 2800 rpm. Simply revving the engine in the driveway doesn't put near enough fuel into the engine to make any real boost.

If you're getting more boost than .9 BAR, the overboost valve should close at 1.1 BAR, killing pressure to the ALDA and limiting fuel enrichment.

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Never a dull moment at Berry Hill Farm.