924Board.org

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

A couple questions...

Poking around under the hood today, I noticed a plug that appeared tobe unplugged all the time I've been driving it around.

So I found the other part that appeared to go with it

And I put them back together

Now here are my questions:

1) what is that?

2) what does it do?

3) since it has not been plugged in all this time, what has it NOT been doing?

4) As I've said before, I've been dismayed at how poor my gas mileage has been, could this have something to do with it?

5) I kinda think that after plugging it back in, that my idle seems to have lowered, but here's the tricky thing. First thing I did was go to Taco Bell and get a burrito. back out in the car, I turn the key and the engine just won't catch. But soon as I UNPLUG that thing, it started right up! What is going on?

I appreciate your opinions, 924, enthusiasts!
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Fred- 1979 924

Grenadiers · Posted: Sun Jan 30, 2011 9:53 am Post subject:

Stay away from Taco Bell?

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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

Nyuck nyuck nyuck

No, really.
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Fred- 1979 924

Paul · Posted: Sun Jan 30, 2011 12:35 pm Post subject:

Looks like someone installed a second cold start injector either to solve the hot start issue or for additional enrichment.

Don't use it.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Feltron · Joined: 11 Jul 2010 Posts: 44 Location: Port Murray NJ

Depends on the year of the car but thats certianly on the CIS and I'm fairly certain that its the anti-roll measure that stops fuel from going to the engine in the event the car is on its roof. Its not another cold start injector. I had to do a work around on mine because it didnt work.

The reason it may not be starting with that plugged in is the same as the problem I had, the car may think its always flipped. To check this plug it in and with the key in the "on" position but the car not running take the cover off the air box and put your hand in. Theres an airflow plate on the CIS that you can feel in the air box, push up on it. You should hear your injectors squirt fuel with the plate up, if they dont unplug it and try again. If you hear it with the plug off then your switch is messed up, apparently you can just leave it unplugged to fix it but what I did was cut the plug and run a permanant circut there.

http://www.924board.org/viewtopic.php?t=34209 This is a link where I explain it to someone with a similar problem then someone links me to a "better" way to fix it than I did. Personally I dont like loose plugs so I'm glad I did the hard wire but its your car do it how you like it.

Smoothie · Posted: Sun Jan 30, 2011 2:16 pm Post subject:

That should be the "Supplementary Start Valve" mentioned here, no? --> http://www.924board.org/viewtopic.php?p=311680#311680
-A factory solution for the hot start problem..
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Paul · Posted: Sun Jan 30, 2011 2:28 pm Post subject:

Could be, don't think I've ever seen one actually installed before....
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Feltron · Joined: 11 Jul 2010 Posts: 44 Location: Port Murray NJ

The supp start valve I think (could be wrong) is the same thing as the cold start valve and that is located on the back of the intake housing, there are 2 allen bolts that hold it into place and if you take it off it looks just like a fuel injector and that also has a blue electric plug. But the blue plug on the CIS (on my car any way) is for the roll-over shut off.

OP if you have the Haynes manual just look in the wiring diagrams and it will tell you wire colors which will help you figure out what things are.

Ozzie · Posted: Sun Jan 30, 2011 10:00 pm Post subject:

the supplementary start valve on the CIS works off a temp sensor in the coolant line and fitted under the coil.
the valve drops the control pressure to help purge the system from vapor lock when hot.
Mine is connected, not sure if it works but hot starts are not one of my problems.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

mikebola · Joined: 07 Sep 2009 Posts: 361 Location: Parkside, PA

IIRC, it's a thingie that shunts some of the fuel pressure to the return line. I think. I forget cause I tore it out of the car along with the complete CIS system as soon as I got it running.

_________________
proud owner of a 1979 924 Sebring Edition with a 931 trans that looks horrible but somehow runs...

Smoothie · Posted: Mon Jan 31, 2011 2:37 am Post subject:

Could it be a 924NA frequency valve then..?
Different location from the 924T equivalent which is mounted in-line at top-front of the intake manifold...
Freq valves regulate the A:F mix on later catalytic converter and o2 sensor equipped 924s.
-Don't know if any '79 924NAs got them, and if so, where they'd be located.
On the 924T, they (freq valves) alter pressure between the upper and lower chambers of the fuel distributor by releasing fuel from the lower chambers back to the fuel tank. If the 924NA device pictured is a freq valve, then it would be working differently - altering control pressure by releasing fuel from the top.
Rattlinbone - can you tell where the bottom outlet of the contraption is connected/leads to? -And does your car have other o2 sensor system components (ie.- o2 sensor, lambda control box, etc.)? -And what colors are the wires on the plug for the doohickey-contraption?
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

If the 924 is a euro or the fuel distributor is off an earlier 924 it could be a hot start solenoid.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

the_mad_electrician · Joined: 16 Nov 2009 Posts: 1073 Location: Central Georgia

I'm pretty sure that my car had that on it but I ditched the CIS so i'd have to look to see.
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81 924 N/A

2004 Ranger "Edge"

2005 Mazda 6

Slam · Posted: Sat Feb 05, 2011 6:09 am Post subject:

Why not test voltage at the plug with the engine cold, then hot. That'll tell you a lot. Also test resistance on the injector connector (hey, I made a funny!) in both situations.

It's the control pressure reduction solenoid, it seems.

http://www.924.org/techsection/3fuel.htm#38%20Frequency%20valve
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'84 944 - kid blew motor
'83 944 - resting comfortably. For 12 years
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'80 924 - gone
'78 924 - gone
'77 924 - rusting comfortably

Harm · Joined: 02 Apr 2009 Posts: 1376 Location: Holland