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.