Vac Eval - Page 2 - PeachParts Mercedes-Benz Forum

Bimmer-Bob · #16 10-07-2016, 11:20 PM

Quote:

Originally Posted by dieselbenz1

Welcome BB and congrats on your purchase these are great cars for sure. Confused whats there to be confused about just a ton of vac lines. However should one become disconnected it will affect shift quality and shifting will be abrupt or harsh. Guess you solved one issue already. Not certain what pic 1 is but the red and yellow are orifice restrictions of different sizes used to limit the amount of vac in a circuit. Could be going to the vac controlled actuator. Have you tested your 0-60 mph time? Above 16 or so and you would have no boost. When I had boost problems I disconnected the MAF by passanger headlight and that restored my boost. I ran it like that for a couple years without issue. You'll find everything you need here

Model 124 Maintenance Manual Index

But do ask.

Thanks for the link!

Do you happen to know what the valve (or whatever) is that is labeled "Vac Out?" Haven't been able to turn up anything with Google yet. Just confused about why I have two dangling vac line with only one unoccupied fitting in the area? I am going to look into simplifying the vac system at some point, to minimize these types of issues, but would prefer to get it working in stock form before I start screwing around with things...

Otherwise, totally loving the car. It's not even close to the performance of my Bimmer, but it's satisfying to drive in it's own way, and has been a pretty fun project so far to tinker on.

dieselbenz1 · #17 10-07-2016, 11:59 PM

Well you should have 3 vac out solenoids 2 up front and that one. It's been a while for me to recall which is which but you can trace the connections. One is for the inlet flapper that closes and the exhaust recirculating valve opens the 3rd one likely the one you are asking about should be turbo vac control. The vac schematic is on rail by the passanger headlight hard to read but it's there.

Bimmer-Bob · #18 10-08-2016, 12:16 AM

Quote:

Originally Posted by dieselbenz1

Well you should have 3 vac out solenoids 2 up front and that one. It's been a while for me to recall which is which but you can trace the connections. One is for the inlet flapper that closes and the exhaust recirculating valve opens the 3rd one likely the one you are asking about should be turbo vac control. The vac schematic is on rail by the passanger headlight hard to read but it's there.

Sweet, thanks for the start.

Bimmer-Bob · #19 10-08-2016, 01:52 AM

OK, based on the part number on the part on pic #1 above, it is an EGR pressure converter valve...but that still doesn't tell me which lines are supposed to be hooked up to it. It seems wrong to have a line from the turbo just dangling loose, but at the same time, it seems wrong to have one end of a 3-way fitting not used. Can anyone provide some clarification here? I have 2 free lines, and only one fitting to which either might attach to...

Bimmer-Bob · #20 10-08-2016, 02:10 AM

OK, last update unless/until someone has a definitive answer to prove me wrong: I removed the line with the red restrictor in it from the vacuum fitting, and then I cut a small piece off of the turbo line to eliminate the tear so that it would fit snugly on the vacuum fitting. After going for a test drive, the car feels more punchy with throttle application, and when I got home, it even seemed like the engine shut down more quickly. Of course, this could be all (or partly) placebo, but it seems to make more sense to me to have a single restricted port of a multi-port line be open-ended than have a dangling hose coming from the turbo.

Shift quality seemed the same with both set ups, so I don't know what to make of that. Honestly, it seems unlikely that these lines and fittings are affecting shifts, since they are on the opposite side of the engine compartment as the line going to the transmission. Maybe the shifts were helped by snugging up those other lines, which I also did. Or maybe my wife is right, and the car "fixed itself," however unlikely.

For now, I'm going to leave it as is, but the EGR delete & wastegate conversion is looking more attractive, if only to eliminate the uncertainty of the current arrangement.

dieselbenz1 · #21 10-08-2016, 08:01 AM

Engine shutting off more quickly solved another vac leak and it does not really matter where the leak originates from many had a climate control vac pod cause lots of problems. The 3 way connector close on top of the vac pump one goes to egr vac CCT including boost, second trans, third climate control. Door locks are on a another vac pressure pump located under the rear seat. Acceleration time?

Bimmer-Bob · #22 10-08-2016, 10:04 AM

Quote:

Originally Posted by dieselbenz1

Engine shutting off more quickly solved another vac leak and it does not really matter where the leak originates from many had a climate control vac pod cause lots of problems. The 3 way connector close on top of the vac pump one goes to egr vac CCT including boost, second trans, third climate control. Door locks are on a another vac pressure pump located under the rear seat. Acceleration time?

Thanks for the roadmap.

What do the climate control vac pods do - just open and close to route airflow depending on ambient cabin temp and temp setting? I'm just thinking, if I find a leak on one of the lines heading to the climate control system, and that leak is affecting other things, can I just plug it in the engine compartment and call it a day? I mean, I know I'd lose the downstream vacuum pods (if they even work), but I definitely don't want to pull the dash and start replacing vac pods if I don't have to, at least unless/until I fix the evap leak (AC doesn't even blow cold right now anyway).

Accel time has not been clocked yet. I generally don't put much stock in 0-60 times, as there are so many confounding variables involved (wheel and tire size, tire brand, but probably esp. driver technique) as to make comparison meaningless. I guess the intended use is to compare my own times before and after making changes, in which case it seems more reliable than the old butt dyno, at least. Will try to establish some baseline runs this weekend, once I settle on a methodology.

dieselbenz1 · #23 10-08-2016, 11:35 AM

You have the vac system nailed now your assumptions are right on.

O-60 in around 10-12 sec is nice for the 124 602 slower than 16 suspect boost problems I don't think any decimal point accuracy matters.

Bimmer-Bob · #24 10-08-2016, 08:52 PM

Quote:

Originally Posted by dieselbenz1

You have the vac system nailed now your assumptions are right on.

O-60 in around 10-12 sec is nice for the 124 602 slower than 16 suspect boost problems I don't think any decimal point accuracy matters.

Did a few 0-60 pulls, and seemed to be averaging around 12.5s, so not too shabby! I haven't even touched the ALDA yet, so I'm okay with those numbers. Even my worst pull (uphill) was just under 15s, so I'm not too concerned about any serious power-draining issues at this point.

My main gripe about DIY 0-60 pulls is the lack of standardization. Elevation changes, turns, and launch all have a tangible impact on results. I did several pulls in several locations, and the 12.5s was pretty repeatable within several tenths, so I think it's pretty good as a ballpark. What would be ideal is an app that used the phones accelerometer to take start and stop control away from the driver, and then one could make several pulls (an even number) back and forth down a straight road (to average out any effect of elevation).

I know, I know - I'm totally overthinking this.

vstech · #25 10-08-2016, 11:35 PM

Plenty of acceleration apps that use accelerometer and gps for timing such things.

Bimmer-Bob · #26 10-08-2016, 11:54 PM

Quote:

Originally Posted by vstech

Plenty of acceleration apps that use accelerometer and gps for timing such things.

I figured, I just haven't looked around too much. I did briefly test one out, but it told me I completed a 0-60 pull in 3.5s, lol. So I reverted to the old-fashioned stopwatch method. I'm sure I could do more research and play around with the right app to get better results.