Good point, Andrew. Also remember than any restriction in line with the ALDA will reduce part-throttle power, as the ALDA will get a delayed signal from the charge pipe. This was the "fix" Mercedes foisted upon the 1986/1987 models to correct a lean surge with the cruise control. It's shown in the FSM complete with restriction orifice, an extra switchover valve, and a bunch more plumbing. With the EGR/ARV disconnected and ALDA adjusted it's not needed - I removed it from my cars. I think you would need more than 1-2 inches of vacuum before it would actually affect fuel delivery but I'm not sure about that.
=) -Dave M. > ---------------------------------------------------------------------- > Date: Sat, 30 Jul 2005 08:05:20 -0400 > From: Andrew Cunningham <[EMAIL PROTECTED]> > Subject: Re: [MBZ] Boost line check valve? > > Casey, > > I have been playing with the signal to the ALDA with the 617 engine, > not yours though. If there is a check valve (at least on the 617) the > ALDA will stay pressurized from your peak boost even after you take > your foot off the go pedal. Until it leaks down to the correct intake > pressure your IP will be spitting out more fuel at a given throttle > position than it should be. Perhaps, Marshall can weigh in and > confirm. > > Out of curiosity, how much is a fair amount of vacuum? > > Andy > > > On 7/29/05, Zeitgeist <[EMAIL PROTECTED]> wrote: > > The latest thread about leaky valve stem seals has gotten me to think > > about the presence of pressure and (a little) vacuum in the intake > > manifold. I've been monitoring my boost pressure gauge and have > > detected a fair amount of vacuum in the intake off idle until boost > > builds. I'm also experiencing a bit of throttle lag off idle, before > > the beast leaps forward with a vengeance, so I'd like to put a > > pressure check valve in the line between the manifold and ALDA, so I > > can test a theory > > (btw: I know about adjusting the ALDA screw or shimming, so hold that > > thought). > > > > Does anyone know of small orifice check valve for either pressure or > > vacuum (I assume these can just be turned around, right?)? Does MB or > > another make use one of these check valves? I've seen vacuum filters > > and reducers, but not a small orifice check valve so far. > > > > TIA > > -- > > Casey > > Biodiesel: > > '87 300TD intercooler (206k)
