wiring help

jcaster · 08:34 PM

Edit: This is a 1984 NA

I rebuilt the engine and now upon reassembly have a few things left to figure out. I have two wires near the driver's side engine mount that I do not know where they go. One is orange/green I believe with a plastic connector and the other is brown with a metal connector. I cannot see anything these would go to but the idle stabilizer valve but the plastic on the one wire makes me wonder. Also at the firewall near the starter connector their is a black rubber type connector that I cant find a connecting end to. I have shown photos of these items. I cannot get the car to start.

HondaDustR · 02-09-2010, 08:48 PM

2nd is the heater connector for the O2 sensor if you're running a 3 wire heated sensor. 1st I have no clue. Maybe the AC clutch?

Did you mix up the speed and reference sensor connectors? Does the tach needle move when cranking? If it does, the sensors are probably correct. Has the fuel system built back pressure after the rail has been drained. Sometimes that can take some cranking if you didn't jump the fuel pump to prime it beforehand. Does the fuel pump run when cranking? Everything is plugged in, especially the AFM. I forget that one all the time.

Outback Porsche · 02-09-2010, 09:02 PM

At a guess, the first one is for the Supplementary Air Valve. When you get it started, turn on/off your A/C and see if you have 12V switching on/off across the terminals (car will idle low/possibly stall with the SAV closed and A/C compressor on). This 'll confirm its for the SAV.

Cheers,

jcaster · 02-09-2010, 09:19 PM

Will car run without the idle stabilizer valve plugged up? And so you guys think that neither of these would be causing the no start?

Outback Porsche · 02-10-2010, 04:09 AM

Quote:

Originally Posted by jcaster

Will car run without the idle stabilizer valve plugged up? And so you guys think that neither of these would be causing the no start?

Nah. Something else is causing the no start. The valve that these wires go to are used to 'up' the idle revs when the A/C is on only. The cold start idle valve is under the inlet manifold and is called the Auxillary Air Valve. It has a connector similar to the injector connector.

My ROW '83 doesn't have an O2 sensor (never did). Starts and runs fine without it.

Cheers,

wild man · 02-10-2010, 05:53 AM

It might help you to know that solid brown wires are always ground wires on these cars.

jcaster · 02-10-2010, 02:45 PM

It appears that I have fuel. I get fuel at the testing cap on the end of the fuel rail during start attempts. It appears that I have spark. I get spark on the end of the plug wires during start attempts. AFM is plugged in. Is it possible that a vacuum issue would cause it to start for about a second or two then die? I may not have the hoses right and the ISV is unplugged. The car ran before the rebuild. Tach bounces during start attempt.

Outback Porsche · 02-10-2010, 03:00 PM

It's possible. This thread had vacuum diagrams for you to check against;

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/480801-vacuum-air-line-diagram.html

Cheers

Outback Porsche · 02-10-2010, 06:09 PM

Quote:

Originally Posted by jcaster

Will car run without the idle stabilizer valve plugged up? And so you guys think that neither of these would be causing the no start?

It should start, as it's normally open for cold starts and slowly closes off as the engine warms.

wgruner · wgruner's Garage

So are these two wires grounds? They have a brownish-orange sheath. They come out of the wiring bundle to the back of the engine and I'm not sure where they go. Thanks!

CatsEyes · 03-22-2012, 05:27 AM

Yep, they're grounds. And they really do need to be grounded to the chassis.

As more experiences souls than I regularly say on these forums: check all your grounds!

Good luck.

johnkoawood · 03-22-2012, 12:54 PM

Quote:

Originally Posted by wgruner

So are these two wires grounds? They have a brownish-orange sheath. They come out of the wiring bundle to the back of the engine and I'm not sure where they go. Thanks!

They connect to the belhousing, should be a bolt hole on the top side near the speed and refference sensors.

And your no start could be caused by the speed and refference sensors being connected backwards... swap them at the plugs and try again!

Techno Duck · Techno Duck's Garage

If you tried to start the car with those grounds not connected, you may have fried the ECU.

wgruner · wgruner's Garage

Thanks for the comments everyone! Yeah I found the stud and bolt on the bell housing and it's a perfect fit. I'm a little ways off from trying to start it, just put a new engine in it and it was quite a while ago that I took the old one out so a little rusty on where everything goes. I'm having a whole different issue with the pulse senders (from what I can tell the plug that sits on top of the harness that's connected to the manifold goes to the pulse sender position in the rear, correct?) and the oil pressure switch, but that's a different story for a different day. Would anyone happen to know where this cable connects to? I have the starter and alternator connected and don't see anything else that fits it.

CatsEyes · 03-24-2012, 04:27 AM

It's a tiny picture, at least on my monitor. But surely that's another ground?

wgruner · wgruner's Garage

It's a long black cable, pretty heavy-duty, and ending in a clasp about 1/2-3/4 in. It has the length to reach down into the front driver's side end of the engine compartment, so I don't imagine it would go any where on the passenger side or rear.

Techno Duck · Techno Duck's Garage

Hard to tell from the picture, my best guess is its for the rear lug on the alternator. What does the other end goto? If it is for the alternator, the other side will goto the starter.

wgruner · wgruner's Garage

The other end looks like it goes to the bundle connected to the batter terminal. Are there 2 or 3 wires that connect to the alternator? I have 2 connected, and the other 2 wires on that line going to the starter. I did see an unused stud/nut on the bell housing by the starter, if this cable is a ground (as suggested above), could it go to that?