Speedy, So what needs to happen is when the tps switch is triggered by the jettronic box should power the solenoid to open the vent to relieve the preesure under boost to get the boost retard? Unfortunately, mine isn't venting and the dizzy is still seeing .9 bar on both sides of the pot preventing boost retard.

Thanks speedy
Diagramed on side of solenoid
port 1 to dizzy
port 2 to atmosphere
port 3 to throttle body
I just tested my solenoid again
3 is blocked unpowered
1 to 3 open
powered
3 blocked
1 to 3 still open
Mine seems to be inop

Eric I appreciate the offer, our host wants , i think $180, I am looking to get rid of the whole vacuum system and go to the MSD 6530. If mine holds no press or vacuum and visually shows rusted out, mine would be a more likely candidate for surgury. It sounds like someone has already seen inside but if we need one busted....I'm game. Hang on to yours for now and I will let you know later.

Guys..I would make sure that the area around the nipple (vacuum pot) is sealed. Water has gotten in my vacuum pot, rusted out and then was sucked into the solenoid to cause my problem.

Mike

I believe that is correct. The energizing signal for the solenoid comes from pin 11 on the 14 pin connector in the engine compartment. Maybe you can check that. The wiring diagram says that it is a red/blue wire.

Guys..I would make sure that the area around the nipple (vacuum pot) is sealed. Water has gotten in my vacuum pot, rusted out and then was sucked into the solenoid to cause my problem.

Mike[/QUOTE]

I think that might be my problem too. I have both ports open because I have EFI with electronic timing control. Maybe water got into mine too, because before I switched, I got the idle speed increase when the engine was cold, and everything seemed to be working correctly. Do you get the idle speed increase when your engine is cold (room temperature) and you start it? If not, that would be another sure sign that something is wrong, since that is controlled by the same solenoid valve.

You guy are cooking!

Hope we see pictures if someone cuts a pot open.


It is starting to seem that there might be a lot of 930's out there where the owners mistakenly removed the solenoid thinking it is part of a smog function, might have malfunctioning solenoids, and or might have malfunctioning pots.

I bet we could come up with an easy way for owners to test there cars from just listening to the RPM change at idle, listening for idle to increase if the vac-retard side is removed, and using a piece of tubing sucked on and placed against one's tong to make sure the diaphragm is not leaking on ether side. Might save a bunch of motors.

Interesting.

As to the .5 volt reading when testing the solenoid,

Chris 356/930 has a strong understanding of electro-mechanical devices and report back:

"To get a measurement of 0.5v, they must be measuring directly across the solenoid's coil instead of the solenoid's supply/power lead to ground.
When poking a dc circuit for supply voltage, one lead on the meter goes to ground, the other probing for supply voltage.
Solenoids are simple devices. In a simple dc circuit, they look like resistors. A 25-ohm resistor (coil) will drop an 11.5v supply by 0.46v.
If by chance they are measuring with a real high impedance voltmeter (most digital voltmeters are high impedance) it's possible to get false readings if probing a wire that's un-energized, bundled with a bunch of wires doing different things. This open ended wire acts as an antenna for noise. In this case/measurement, the reading wont be stable, the voltmeter will read 0.45, 0.7, 0.24 etc. If one is looking at a dc circuit with a high impedance meter and the reading isn't rock solid for several seconds, the meter is sensing noise not a dc power level."

Thanks Chris.

Speedy's post #154 describes the inside... still want to cut one open?
I can probably do it tomarrow if needed. Any suggestions on where and how to cut not to damage what we want to see ?

Do you think my problem is related to all this?
When cold idle is high as it should be than after a min or two it drops to 800 . If I sit in trafic after driving alot the idle will go up to 11-1200rpm .I do not think I have air leaks I removed the aav and tested the aar.can this be related to the blue vacuum since the idle is raised by 300rpm ? When this hapened I disconected the blue line at the dist and no change of idle. And I did have some vacuum at the line .
Thanks

OK, went out for a nice long drive this morning, with vac retard pot disconnected and line plugged. Car is sooo much nicer to drive! It is noticeably smoother, has better throttle response down low, and the transition to boost is smoother. Before you could actually feel the transition to vac retard, now much smoother. I believe my car, before did not have boost retard, and while the car was noticeably faster on boost, it also felt like it would grenade if I held the boost up too long. Now it doesn't kick quite as hard, it feels very smooth and stable in full boost, and I feel comfortable maintaining full boost. Who knows what kind of damage I have done without the boost retard function, but I am glad I stumbled onto this thread and realized something is wrong. I do plan to rebuild the motor soon, and hope to optimize the timing on a dyno and it seems like an MSD system with boost retard might get me closer to optimal timing.
Eric

Ertech, That sounds like something WUR related to me, have you checked control pressures?
Eric

"When cold idle is high as it should be than after a min or two it drops to 800 . If I sit in trafic after driving alot the idle will go up to 11-1200rpm"

Mine does this after sitting in traffic or traffic lights alot too accept it only crawls up to about 1000-1100 rpm after being stable at 800rpm for a while.
If I take it out on the interstate and beat on it a little then the idle is back down to 800 afterwards and I don't know why it does this but i think it has something to do with heat transfer back up into the injector blocks and intake manifold and creating small vacuum leaks somewhere around the plastic injector blocks when stuck in traffic or driving way slower than the car was designed for, for extended periods.
Then while driving fast maybe the intake manifold, injector blocks and intake ports are cooled down a little and the idle speed returns to 800rpms for some reason...
..well, I don't know why it does this and I'm just guessing why.

The origonal 930 owners manual even warns against "overheating the intake ports" when idleing the motor for extended periods while adjusting the idle mixture CO.
There must be a reason for that but it's going off topic of this thread.

If you have the two connection pot and disconnect the hose on the nipple closest to the distributor when the motor is running, the rpm's should increase as this takes away the vac-retard function.

If you have vacuum at idle at that source / house that is good.

If you want to check the vac-retard side of the pot, put a length of tubbing on it and use a hand vac to see if it holds vacuum. Or, suck on the length of tubing and stick it on the end of your tong to keep it under suction. If it dose not hold a vacuum you pot is probably not function correctly.

The increase in rpm when cold is just the AAR doing it's job. However, sometimes as they start to go they will be a little unreliable. Then they just out right fail.

And yes, the WUR can effect AFR and idle speed to.

Eric,

That is great. If you wanted you might consider advancing the base timing and see how your car responds. Other's have found an increase in throttle response from doing this.

If you have been running with out boost retard and now have retard, that is about 10 deg of difference.

If you advance your base timing 5 deg you will be half way between where you are now and where you were on boost.

When I first started looking at the 930's timing my first thought was to just disable the Vac-ret side thinking it might add just a bit of crispness off idle.

It sounds like a 930 can handle something like -18 by 1500rpm. Thus, when we get past how things work, it might be that we can advance total timing and use the vac-advance as a performance improvement instead of a smog function and still also for easy start and idle operation. The limitation is probably going to be how much timing we can run on boost.

This is getting really fun! :)

I have the vacuum opened with lots of pics...I will post them shortly after I resize

You've done open surgery on your vacuum pot with pictures?

This is the nicest and fastest image resizer I've ever used and it's free. You can do single pics or batches with one click. Try that with photoshop! ha..
If you try it set the jpeg algorthm to lanczos3 for the best quality and anywhere up to 50% sharpening works good for non people pics.
Easy Thumbnails Software -- Free thumbnail utility from Fookes Software

This is going to be interesting to see the insides.

Where on Hutchinson Island are you? The south end is so beautiful.
Jenson Beach is just up the road a little from West Palm.

Some day we may organize a South Florida 930 and 911 get together, seems like there's around a dozen or so of us down here from Martin county on down.

What is the goal timing on boost?

This will vary from motor to motor depending on build, fuel quality, and environmental factors.

I just though it mightt be useful to establish some reference points.

-Stock 3.2 with 9.5/1 compression runs about -20 to -25 at WOT.

-Stock 3.6 (w knock sensor) and 11.3CR runs about -13 stock to about -18 for the 993RS.

-Steve W. opinion with reservations for a 7/1 930 was about -18 to -20 mightt be possible.

A 930 with 7/1 CR at .8 bar boost running SC cams has an effective CR of about 10.25.

A 930 with 7/1 w 1 bar is about 11/1.

A 930 with 8/1 and .8 bar is about 11.25

A 930 with 8/1 and 1 bar is about 12/1.

Added heat from turbo charging will be a factor. Most EFI ignition settings are modified depending on intake air temps.


-If the boost retard is -10 a setting per factory graph. (-8 to -11 per tests we and other's on the board have done.)

Starting at -26 at 4000rpm gives us about -16 on boost.

Starting at -29 gives us about -19 on boost.

Thus, the upper limit I would even try without better support might be -29 at 4000rpm making sure I had boost retard (disconecting Vac-retard to bump idle, then vac pump test at idle for idle drop). If running more compression or boost with a stock inter-cooler I would keep it at -26/-16.

Just a thought. ;)

Here is an extreme example of turbo timing. I do not know what the compression ratio was but at 32 lbs of boost is dose not matter any more.

http://forums.pelicanparts.com/uploa...1254508318.jpg

http://forums.pelicanparts.com/uploa...1254508344.jpg

http://forums.pelicanparts.com/uploa...1254508367.jpg

http://forums.pelicanparts.com/uploa...1254508378.jpg

http://forums.pelicanparts.com/uploa...1254508396.jpg

http://forums.pelicanparts.com/uploa...1254508429.jpg

http://forums.pelicanparts.com/uploa...1254508445.jpg

http://forums.pelicanparts.com/uploa...1254508461.jpg

http://forums.pelicanparts.com/uploa...1254508499.jpg

http://forums.pelicanparts.com/uploa...1254508544.jpg

The outer pot was sealed but that orfice air would have been able to get through
to the back of the advance diaphram. Look at next pic. The orfice air would get through the oversize hole.

see next post for last 4 pics

http://forums.pelicanparts.com/uploa...1254508734.jpg
Caption on this pic is wrong retard side pressure or vacuum would be able to get between
the 2 diaphrams due to the orfice.


http://forums.pelicanparts.com/uploa...1254508777.jpg


http://forums.pelicanparts.com/uploa...1254508790.jpg


http://forums.pelicanparts.com/uploa...1254508818.jpg
Caption found incorrect... the center is where the control rod comes out the back and is open to atmoshere. The rest is the back of the retard bellows.
The outer shell of vacuum unit houses a very thick pot. The nipple passes through this shell and is pressed into the retard/inner pot.

Wow, that thing had water corroding and killing the insides for a while.
It's hard to tell what is what inside that vacuum pot anymore.

It sucks that Porsche put the 911 distributor and ignition coil right where rain can and will soak it down everytime if given the chance.

Then on top of that add the salt in the incredibly humid here in Florida air near the coast and...

Thats Zane Coker's incredible water to air intercooled amd turbocharged BMW he built.

I've seen it in person and it starts right up cold and runs perfect.
He knows Haltech EFI very well.
The attention to detail and quality of fabrication he has done is absolutely incredible... I hope I get a ride in it someday.

He's rebuilding his 930 engine in his free time right now.

Copterdude,

You are the man!

Looks like condensation leaks down the vac line and sets on the dist can. Maybe inside and out. A little longer tube with a dip at the bottom might keep that from happening.

Will study it further.

Are there limit stops built into the linkage arm?

If so we might be able to increase boost retard range which could come in handy.

The back of the outer pot and inner pot are press fitted back to back and have no stops...appear to be limited by the flex in the diaphram. The notched out area on the control arm is where the springs were in the retard pot.

See 2nd layer diaphram pic.

In the center is where the pots were back to back and fixed. I had to pry the outer diaphram off. It did not take much as rusty as it was.

Thoughts so far.

I am thinking the large diaphragm is best described as the Retard-Diaphragm. Our pot only retards and I believe this is the only working diaphragm.

On a single connection Vac-Advance pot there is a nipple on the outside that feeds the chamber that is sealed. The back side of the diaphragm is open to atmosphere thought the linkage hole.

With a double connection pot we can not just add a nipple to the back as the air would escape out the back with no effect. Thus, with the double connection pot there needed to be a second seal to retain the pressure.

Not sure I see clearly how the nipple on the back of the pot is connected. Is there a hole in the pot around its connection? Is the nipple hard plumbed to the plate we are calling the back diaphragm?

If so this is how the air gets behind the retard diaphragm.

----

It dose not look like the boost side of the retard diaphragm hits the outer shell to limit movement. It looks like the notches in the linkage limits its movement.

I know that Bosch mechanical advance is limited by 2 pins that are restricted in their length of movement by 2 slots in an adjacent steel plate.
You can take a small carbide bur on a die grinder and grind those slots longer to increase the amount of total mechanical advance or partially braze them up with a brass rod and small acetelene/oxygen brazing tip and then regrind them so the slots are shorter to decrease the amount of total mechanical advance.

Just a thought and maybe the vacuum advance has a similar stop that can be modified if you want.

I think altering or shortening the total amount of mechanical advance by shortening those slots and then advancing the distributors static timing the same amount of degrees to make up for the difference is a start.

That would give you more ignition advance at idle and cruise for better low speed response without doing anything to the vacuum lines and cold start vacuum retard solenoid and it doesn't cost hardly anything compared to the MSD retard boxes, it just takes some time disassembling the distributor and experimentation with brazing, grinding, and fine sanding till you get the ignition advance curve where you want it.

The visible outer canister is just a cover. The rear/inner pot nipple goes through a larger hole in the canister and is pressed into a very heavy/thick pot. that pressure or vacuum moves the diaphram back and forth. i reassmebled best I could and the notches do not have anything to lock against. That rear diaphram looks to have had very limited flex. The diaphram was actually a strong sealed cloth material seal around edges with rubber around outer edges giving it flex.
That orfice hole, when acted by press/vac would be pushing and pulling on both diaphrams at same time. Because the orfice is small it, would have just made the press/vac more slow to act. The outer would be immediate and large action.

Jim, I like that idea.

Today, while thinking this whole thing over, I came to the realization that the MSD boost retard does have it's limitations. Without going into huge detail, understand this: the MSD unit retards up to a maximum of 15 degrees, based on how much boost pressure you feed it. With our cars boosting 12 to 14 pounds, the MSD will always achieve the maximum 15 degrees retard...regardless of whether you want it to retard that much or not...because it needs to be set to prevent too much advance at the onset of boost. In my case, with my static timing increased to 8 BTDC, I have the MSD set to shave all those 8 degrees off by the time my boost reaches .3 bar. But...and here's the but....there is a lot of boost left to build, and the MSD will continue to shave off timing until it's reached it's 15 degrees max. So net-net, by the time I'm on full boost, my timing is actually 7 degres less than it would have been without the MSD. In other words, around 9 BTDC at full boost, vs. stock of around 16 to 18.

So, it would appear that gaining the bottom end off-boost response has a price to pay in less advance on full boost. I suspect I'm losing some of the turbo kick because of it.

Thoughts anyone? Unless I misunderstand the MSD's functionality, this is worth exploring. The only way to compensate would be to start with more static advance (like 14 degrees), so that your net timing loss after the MSD retards 15 degrees would be only one degree of additional retard on full boost. And 14 degrees advance is a lot of timing. Make sense? Or am I smoking the wrong stuff in my pipe?

Mark,

If you keep using your MSD in series with the stock retard and you advance your timing 8 deg and want to keep the same amount of stock retard. I would take the 8 deg and if ruining .8 bar take 14.7x .8= 11.76 lbs of boost. You would want 8 deg of retard with 11.76. Thus, 11.76/8 = 1.47 deg per bound of boost.

So, if you set the MSD up so you have 1.5 deg of retard per pound of boost you should come in where you want.

If you want to run 1 bar just do the math. 14.7/8= 1.84 deg of retard per pound.

Having said that, I like the idea of not running it in series but in place of the factory retard.

If you goal on boost is say -18 and you have 15 deg of retard, you could run (18+15=) -33 deg of advance on cruse. At one bar that would be 14.7/15= .98 deg per pound at the most.

If you want you could have it reach full retard earlier by setting it at more than 1 deg of retard per pound.

If you do set it at -33 on cruse, with 18 deg of mechanical advance you would be at 18 deg at idle. If you keep the Vac-Retard functioning you would start another 10 deg lower at idle or at about -8. If you need more mechanical advance do as J says.

Might be a great set up.

I am just not sure how fine of adjustment you can put on the MSD and if you can lock it so it dose not get bumped.

I like the idea of fine tuning the stock set up.

A better set up would be a programmable system set up with RPM by load (vac/boost) and be able to trim the timing depending on the air temp at the exit of the inter-cooler.

This way we could bend the timing curve around any sensitive area like TQ peak or a lean AFR at upper rpm and still have the timing protection of pulling back timing on a hot day for safety.

Could pick up preboost, shorten lag, and increase cruse efficiency from running closer to the ideal.

Would take an investment in tunning.

With the pot do we basically have three pistons.

One on each side of the large retard disk and one smaller one that is the seal that keeps air from escaping out the linkage hole?

The way it looks to me
1. The outer pot is sealed and can move in and out with vacuum/pressure
2. The inner pot is orficed to act on both of the diaphrams. The retard diaphram and then as the pressure/vacuum continues to build it sucks or pushes the outer bellows to assist.

Hey 911

356-930 #27 post
c. P/N 6420 with P/N 8977, aka MSD 6AL with Multi Function Ignition Controller with Boost Control. Improves on a. and b. by providing control of ignition timing by rpm and boost retard onset and rate (up to 25 degrees retard). Boost retard is "additive" to any timing map. In other words, lets one build a detail/custom timing map.
This digitally controllable system can be used to eliminate the distributor’s vacuum/boost advance/retard and mechanical advance.

The 6530 replaces these 2 units and I understood it had up to 25 degrees retard?
If that is correct would it not work better?

It is not clear in my mind how vac/boost gets into the inner champer.

Is the nipple in effect hooked directly to the inner chamber?

If not, would not air pass out the linkage hole?

J,

I had been thinking about this. There is something else we have to keep in mind. Lets say for example we shorten the mechanical-advance function 25%. This will also quicken the time that we achieve full advance by about 25%.

Thus, if we were starting at 1000rpm idle and achieving full advance by 3000rpm. After shortening the weights travel we would see full advance 2500rpm. (25% of 2000rpm range)

This might actually work to our favor.

Assunming we limit advance on the outter end of the weights travel. If we do in on the inner range of travel we migh still get full advance by 3000rpm but we would then proably not see a start of any mechanical advance untell about 1500rpm.



Our main limit seems to be how much timing we can take on boost first. If we could increase this we could bet more advance at idle and on curse.

Then we could shorten up the mechanical-advance to get to our ideal on idle assuming we can still use more advance there.

K

Mark,

Your degrees of retard is adjustable from 0*- 3* per pound of boost. You can take out !/2* pr. pound for a total of 7* at 14lb. of boost if you want. You don't have to use all 15*

Cole

The boost retard function on the SafeGuard has "Start" and "Rate" knobs.

The Start knob lets you set at what psi boost retard will begin. The adjustment range is 0 to 10psi.

The Rate knob sets the amount of retard per psi, and is adjustable from 0 to 2° per psi.

The adjustments can be accurately set using a voltmeter in conjunction with the test points on the front panel. For example, if you don't want boost retard to begin until 7 psi, adjust the Start knob until its test point reads 7v. If you decide you want 1.5° of retard per psi (above the start point), adjust the Rate knob so its test point reads 1.5v. At 14 psi with these settings, you would have (14-7) * 1.5 = 10.5° retard.

The unit also has a FI/NA mode switch that moves the start point by 10" hg, so if the Start knob is set to 0v, "Boost Retard" would start at 10" vacuum. This would be the equivalent of vacuum advance. As you step on the gas and the vacuum drops below 10", the unit would start to retard.


The knock retard function has ten steps of retard. The step size is either 1° or 2°, set by the 10/20 mode switch on the front panel.

The amount of retard per knock event is proportional to knock intensity. The controller can retard up to 14° with a single knock event, applied to the knocking cylinder the next time it fires. Timing on the other cylinders is not affected unless knock is detected in them.

You may be thinking "Oh, it doesn't do anything until it hears knock." You are absolutely correct. However, it responds to knock YOU cannot hear. When you adjust the timing, you really have no idea how close you are to audible knock. How many engines have been lost where the driver said "I never heard it knock."? SafeGuard will prevent that, while optimizing timing in each cylinder.

pic removed see next post

OK, I can't stand it any more. Here is what it looks like in cross-section. It is shown in the full pressure retard position.

There are two diaphrams. The left one is like a donut. The right one is like a dinner plate. The thing in the middle is not a diaphram. It is a damper to keep the rod from shaking back and forth when in the mid-stroke position. The orifice is to make sure that air from behind the right diaphram can escape to the outside. More later.

http://forums.pelicanparts.com/uploa...1254624778.jpg

Speedy
Does the orfice bleed down the center and out back or into pot and out nipple.
The one I tore apart is a bunch of rusty a$$ pieces bent up fro deconstruction.
Cant really tell
Thanks