82sc vacume / timing problem

[porsche930dude]

The main problem with my engine is when i attempt to time it i disconnect the vacume lines and plug at the distributor and the idle rises to 1500 rpm. Also the idle ajustment screw does very little to change this. This prevents me from setting it to 5 degrees at 900rpm. So currently it is at 5 degrees with the vacume connected. Before i messed with it it was at tdc at idle and the vacume lines connected. At that setting it was alright but had a severe lack of getup when warming up. And i read somewhere that that was wrong. So now at my current setting it does not do that but it does have high idle sometimes like when i restart after its been sitting a short while and intermittenly at stops. Also i just serviced the distrubutor but it had no affect on its preformance (this thread is relatively continued from this thread Distributor service (Clean and lube) real easy without removing the pinion gear!)
So i am attemting to find out if my vacume lines are doing as they should since im under the impression that idle is not suposed to change when the vacume lines are disconnected.
My retard line had lots of suction at idle and drops off when reved up. My Advance line has very little at idle and gets stronger under load and when reved up but still not as much as the retard.



Back of the engine



According to these diagrams from hayes and the engine lid. There is suposed to be a T between the decel valve and the throtle body going to who knows what. My car doesnt have a T and the engine lid diagram doesnt have one either so which is correct?


Also the hayes manual has no vacume line going from the wur to the throtle body so is that correct

Now if thats not enough i found these wires at the back of the engine that go nowhere. One is short like it should go to the back of the engine and the other is long like it could go to anywhere

[Gunter]

Forget the Hayne's.
The wire with the plug may be for the heater blower. Is the blower gone?
The other wire may be cruise control. Is the cruise gone?
The WUR connections look good.
We are going around in circles and I cannot help you unless you answer the questions I asked you on the other thread.
Do you still have the Thermo-time Valve in the loop? It has an electric connection and 2 vac lines and could be the thing under the pope's hat?
What's under the pope's hat?
The WTF item and T is for the cruise control. If you don't have cruise, that's why no T.
Do you have a strobe light?
Timing is set with vacuum DISCONNECTED at 5 deg BTDC @ ~900 RPM
(Use the Fast idle screw to regulate the RPM)
Are you doing that?
This is no rocket science; throttle it down with the screw and move the distributor to retard the timing.
Set the timing first according to factory specs, then connect the vacuum.
Make sure that the advance goes on the right nipple on the vac pod!!!That's the FRONT of the pod.
Even with the lines connected at idle, there should be no change in RPM.
Show me a picture of the hold-down bolt/nut of the distributor when you have it set. (I need to see the position of the distributor after timing is set)
What max advance does your strobe light show at WOT?
The small vac line from the Decel Valve can go to the rear of the TB but, I have also seen it go to the bottom of the WUR if there is a nipple on the side.
The larger vac line is in conjunction with the AAR and AAV.
Can you take pictures with a little wider view?
Show the whole engine lay-out from all sides in a wider view..
And, I need to see the rear of the TB where the vac nipples are for vac brake booster, advance etc.
Read it again and answer all questions, we'll get there!

[mca]

Originally Posted by porsche930dude

So now at my current setting it does not do that but it does have high idle sometimes like when i restart after its been sitting a short while and intermittenly at stops.

Sometimes a intermittent high idle can be caused by a faulty decel valve. It may be a good idea to pull the vacuum line off of the decel valve and plug it with a golf tee.

See if you still get intermittent high idle AFTER the car is at operating temps. If so, you can rule out the decel valve as the culprit.

If plugging the decel valve vacuum line solves the high idle problem, PM me and I can explain how to fix the valve without replacing it.

[fireant911]

Subscribed - I have the identical problem. You can rule out any distributor problem causing this - I purchased a new distributor and the same problem lives on. The idle will not come down when the vacuum lines are removed and plugged – nor will adjusting the idle screw bring it down to the target value. I 'think' I tried the bit with the de-acceleration valve - no effect. Restarting after shutting off also results in a high idle - are these two characteristics related? I know that if continuity is broken from the oxygen sensor to the Lambda brain that the high idle upon restart will immediately disappear (I installed a switch for this very purpose). I too would like to know the cause of this abnormality.

[munsonbw]

Not to hijack, but it is relative to the post. I am resetting the timing after a rebuild. I should have known to adjust the timing with the vacuum line disconnected... momentary lapse. I should plug the line, correct? Also, Gunter you mention the advance at WOT. Are you really suggesting to rev out the engine to WOT and check the timing? I guess it would be fine, as the car does this on the road, but I though I read here about running the engine too fast under no load being a no-no.

Thanks,
Ben

[Gunter]

I am waiting for some specific answers from Porsche930dude before going all over the place again.
I would also check the base setting of the throttle plate (Butterfly) to make sure that no excess air goes by and that the fast-idle screw really controlls the airflow as intended.
BEN: Yes, you can set the timing the other way round by going maximum advance (About 30-33 degrees vacuum connected ) and then it should settle at ~5-7 deg BTDC.
Make a white mark on the pulley at 33 deg (33 deg is 33mm from Z1) use your strobe light and see the mark at ~33 deg around 6000 RPM.
Revving the engine to 6k does no harm.

[Walter_Middie]

Ben,

Just to be clear - you don't have to rev the engine up to 6000 RPM and leave it there while you casually adjust the timing. Do as Gunter suggests, and make a mark on the pulley, then with the timing light pointed at the pulley, rev up the engine. At some RPM, you will notice the timing will stop advancing. Let the car idle, make any adjustment to the timing you think you need, and try it again. It's a little trial and error, but you are at high RPMs only momentarily.

[Vereeken]

Originally Posted by Gunter

BEN: Yes, you can set the timing the other way round by going maximum advance (About 30-33 degrees vacuum connected ) and then it should settle at ~5-7 deg BTDC.
Make a white mark on the pulley at 33 deg (33 deg is 33mm from Z1) use your strobe light and see the mark at ~33 deg around 6000 RPM.
Revving the engine to 6k does no harm.

Indeed. Just make sure you put the mark for 33° 33mm to the right of the Z1 mark (CW). There is a dumbass belgium that tought it should be to the left

I also found this weekend that my 83 SC (last of the batch) had the vacuum advance line connected to the back of the throttle body. When going in the throttle body I noticed this line was not sucking vacuum, which was normal cause inside the throttle body the vacuum was blocked with a blanking piece.
For 83 SC with only vacuum advance and no retard, the proper way to connect the line is at the front left of the throttle body just next to the vacuum line for the WUR. That and setting the timing right solved all my weird cold running problems. Gunter is this correct, cause of course it could also be that I messed things up and that the weird combination of things also solves the same issues.

[Vereeken]

Originally Posted by mca

If plugging the decel valve vacuum line solves the high idle problem, PM me and I can explain how to fix the valve without replacing it.

Indeed that can be the problem but please share with us how you fix the decel valve without replecement.

Michel

[mca]

Originally Posted by Vereeken

Indeed that can be the problem but please share with us how you fix the decel valve without replecement.

Michel

All you have to do is pull the decel valve and place it in a vice. Compress it ever so slightly (not on the circumference) - as if you were flattening it more than it already is. Reinstall and all is fixed. There are a few threads out regarding this process (search on "decel vice").

[porsche930dude]

First off i have no heater or cruise so that explains that. also i see nothing back threre thats missing wires.
Im not sure what the thermo-time valve is do you mean the auxilary air regulator?
Timing is currently set at 5 degrees and 34-35 at full advance with the lines connected and it runs awesome! Im begining to beleive the lines disconnected method doesnt apply to my car. I almost think i shouldnt mess with it anymore.
I cant take pics with a wider view it was zoomed all the way out as it were. Also the advance line and decel line have been pictured. Also i switched those vac lines to see what that did and it only raised the idle because there was more suction in the line to the decelvalve.
I have not yet checked the throtle plate.
Also im not sure if i saw the aux air regulator back there where is it usually mounted? I also have to check the lines to the aav if they are in the right spots
Heres a pic of the dist current location and the brake booster line. You can also see where the decel line goes into the tb and the advance runs around the back to the other sise of the tb

[munsonbw]

Thanks for the tip, Vereeken. Just checked my 81 RoW and found I have the exact setup you do... and my vac line is attached to the back of the TB and the line by the WUR is plugged with a golf tee. Fun things you find. I also have weird cold running issues that mysteriously got better after my tear down. I suspect it is timing related and I need to do some more digging.


porsche930dude,

I am no expert, but I'll see what I can do to bring more information to the surface. First, I too find your pictures to be very hard to orient myself to. At the risk of sounding like a smart ass; if the camera won't zoom out, move further away. I like to take a few pics of the same subject at different lightings, distances, flash, etc and pick the best once you have them at you computer.

Now, lets start with the wires. It looks like a green/yellow on the left and a dark green on the right? Looking at the Haynes manual, the gn/ye COULD go to the 35C temp switch from the "control unit accel enrichment", which looks to be part of the Lambda system. The Haynes book kinda stinks in this regard, but it may be one of you temp switches is missing a wire or is mis-wired. Please clarify the other wire color and I can offer ideas as to its home. You'll have to dig from there and see if it makes sense.

Your second and third pics show what appear to be some very non-factory stuff. The third pic show a tube that has a rubber end to adapt to the TB. On my 81, that TB attachment feeds the decel valve. If that copper tube ends up at your AAR, then your system is suspect. The AAR comes from the right side of the car and I loose it behind the airbox. Someone with their motor out may be able to snap a pic.

My only slightly educated opinion: take some time and research what your car's CIS system SHOULD look like and correct yours. You may be chasing your tail with vacuum issues caused by AAR, AAV, etc that only affect your situation when they are active (or inactive).

Good luck,
Ben

[Gunter]

O.K. Porsche930dude:
Going by the picture, the distributor position looks normal.
I think you are getting false air from the AAR, AAV, Decel.Valve into the bottom of the TB.
That means the idle speeds up just enough to activate the mechanical advance and screw up timing efforts and mixture.
Check the AAR located on the right side of the engine.
It's the item that has a small electric plug and a large vacuum hose connected to it.
Open the clamp holding the hose.
Pry it off with the screwdriver just enough to slide it under to get it out of the way so you can see into the opening.
With a small mirror and a light, peek inside.
When COLD, you should see an opening in the valve shaped like a half-moon.
When HOT, the opening is completely closed.
If it isn't closed, the AAR is either kaput or doesn't get any power.
You can spray some WD-40 into the valve in case it is just sticky.
To check the power, carefully open the tiny clip on the plug with a very small screwdriver and pull it off. The wire clip is tricky but necessary; don't yank it off.
Start the engine and check for 12 V. (One wire is power, the other is ground)
Let me know if the AAR works HOT and COLD.
BTW: 35 deg max is a little high. You don't want to get detonation in midrange.
Try 32-33 to be on the safe side after the AAR-check.
What octane are you using?

Vereeken:
The line for advance goes in the REAR of the TB, the line for the WUR is correct in front.
One has to be below the throttle plate, the other has to be above.
That way, idle is controlled with the Fast Idle Screw on the left side of the TB.
Euros don't have a retard like the US '80-'83 with Lambda.

[porsche930dude]

Gunter i checked the aar with your instructions and it works great. Im going to check for outside air leaks next. Last time i did it with a smoke machine i was getting alot of air coming out of the seams of the charcol canister what can i do about that do you think that would affect anything?

As for the wires munson i see what your refering to on page 315 of hayes. the one you questioned im pretty sure is blue/ green which also goes to a 15 degree tempreature switch and the green/yellow goes to a 35 degree temp switch. the next question is what are those switches. I looked in the book to locate the cruise control wire color with no success but i know the bl/gn wire could have come from there. Also the oil thermostat behind the engine has its wire so it doesnt go there.
As for the aar and aav and decel connections and tubing its pretty much impossible to see anything back there with the engine in but those should be correct because the lines are hard lines and only point to one spot. Unless like on the aav there swaped . But the car runs great. I dug up some timing specs it should be about 10 degrees and 33 full advance with the lines connected and 5 and 21 with them disconnected. So that says to me is your car really messed up or is that how its suposed to be.

[munsonbw]

Well, again the cryptic Haynes manual is only somewhat helpful. My first guess was the thermotime switch, but I see that has re/bk and ye wires. Probably not that then. Judging by the theme of the items on that diagram, I would look at all of the CIS items and ensure every male spade is used. I would not worry about them unless you have time on your hands to trace them through the harness.

[Gunter]

Originally Posted by porsche930dude

Gunter i checked the aar with your instructions and it works great. Im going to check for outside air leaks next. Last time i did it with a smoke machine i was getting alot of air coming out of the seams of the charcol canister what can i do about that do you think that would affect anything?

NO effect, the airbox sucks the fumes from the canister through the hose.
Check for vacuum leaks the traditional way, acetylene torch with a small nozzle is best, quick and easy.

I dug up some timing specs it should be about 10 degrees and 33 full advance with the lines connected and 5 and 21 with them disconnected. So that says to me is your car really messed up or is that how its suposed to be.

Forget the Haynes, get the Bentley SC Repair Manual.
You are wrong about the timing, something is still wrong.
With everything working as it should, and for the third time, the timing is:
5 deg BTDC @ ~900 RPM with vacuum connected for an OEM '83 US SC.
Why ignore the factory specs?
A stock '83 US SC has a LOT MORE Lambda components than '78-'80 US SC's.
Get the Bentley so you can find the differences and the wiring code.
Lots of good info in the Bentley.