Wiring for WUR on '74 with 2.7 CIS

[azasadny]

My mechanic came over the other day (Tab Tanner from Autobahn Garage in Findlay, OH) and took pity on me and my car. He told me to pull the spark plugs and replace them because they're fouled and to test my WUR and replace it if necessary with a replacement WUR. I have a "spare" "known-good" WUR from my old engine, but the old WUR had a two prong electrical plug on top and one line went to the #2 fuse on the rear engine compartment fuseblock and the other went to a ratty looking cable on the engine shroud. The WUR I just removed from the engine only had one wire connected to it and it connects to a striped wire on the engine shroud.

How should my WUR be connected? I'm trying to use the "known good" WUR that has the two prong electrical plug on top. I pulled 5 out of the 6 plugs so far and they are really fouled up, and I still have to remove plug #1. I'll be picking up new spark plugs tomorrow and I want to be sure I have the WUR hooked up correctly. Anyone know where the wires should go? Thanks!!!

[Bobboloo]

On the 2-pole conn. regulator one pin is positive the other is ground. Just run a wire to ground for the ground pin. The positive pin goes to the 14-pin conn. and from there to the WUR relay on the relay panel.

74' cars have an independent relay for the WUR unlike later cars that used the fuel pump relay. You can pull the relay and check for continuity between term. 87 of the relay socket and the wire that's connected to the WUR. If it's good then all you have to do is determine ground on the known good WUR. Check for continuity between the body of the WUR and the two pins to determine ground.

[azasadny]

Bobby,
Thank you for the much-needed info, I'll hook it up this evening and start testing!

[Bobboloo]

Hi Art,

When I was out in the garage tonight I decided to check and make sure one of the terminals on the 2-conn. WUR is grounded to it's casing. To my surprise it isn't so my suggestion for finding ground on the WUR won't work.

So I decided to trace which pin is positive on my 77' 2-conn. WUR. Well it turns out that the left/driverside pin is positive and the right/pass. side pin is neg./ground. This is with looking at the WUR mounted on the motor.

[azasadny]

Bobby,
Thanks! I'll take a look at mine today and se if I wired it up correctly. My car now starts and runs well, but stalls every time I'm at a stop, not accelerating. The car doesn't backfire or stumble at all, just idles slowly, then dies at evert stop sign. Looks like I have more adjusting to do.

[azasadny]

I replaced the fouled spark plugs and the WUR yesterday. The car now starts good cold and idles at about 950rpm, but then tends to stall every thime I decelerate or come to a stop. It is idling too low, but the idle speed screw doesn't make any changes at all. Once the car wamrs up and stalls, it's hard to get it restarted and I have to crank the car numerous times to get it started. This is a continuation of the problems I've had since June. After replacing the engine, CIS, fuel pump, WUR, coil, plugs and wires, CD unit, etc... The car still has a problem and I can't drive it. I'm at my wit's end...

[Porsche_monkey]

1) Have you checked your fuel pressures? 2)The idle speed adjustment issues makes me think you might have an intake leak somewhere, which could be leaning out your engine. It might be starting properly because the cold start injector richens your mixture, then it leans out as it warms up. You should also pinch off the air-intake from the AAV to make sure it's not an issue.

[azasadny]

I have not checked my pressure yet. I don't have an AAV on my '74. I've replaced every vacuum hose, fuel line, etc... so I don't have an air/vacuum leak. I just replaced the WUR, but I'm not sure if it is wired correctly...

[Porsche_monkey]

Isn't the AAV the device that lets additional air in during cold starts, or is that the AAR, I get these mixed up. I think your car should have one...

You could easily have a cracked air-box, that is quite common. I would not rule out anything at this point. You might try running a propane torch (valve open, no flame) around the intake box and hoses. If the rpm's jump up you have a leak.

[azasadny]

PBH,
I just replaced the engine and CIS and when I did, I checked everything and so did a Porsche mechanic. I think I may not have the WUR wired up correctly. The old WUR had one wire connected to a striped wire on the shroud and the "new" WUR has two wires and I'm not sure which wire goes where. Being color-blind does not help... Thanks!

[Bobboloo]

Art,

Here's the current flow for the WUR on a 74' CIS car.

D+ (blue wire) of the voltage regulator goes to term. #86 of the cold start relay (relay beside the rear fuse block). This provides control voltage to throw the relay switch.

Term #85 is ground for the relay.

One of the three fuses on the rear fuse block is for supply voltage. It should have a red/white wire. This goes to term. #30 of the relay and provides the supply voltage for the relay.

Term. #87 on the relay transfers supply voltage via the 14-pin to the WUR. This also a red/white wire inside the engine harness.

As stated before the other term. of the WUR goes to ground to complete the circuit.

Go down the line and check for continuity. If you find anything open then you've found the problem.

P.S. Obviously the fuse for the WUR and the cold start relay need to be in working order for the WUR to get current.

Also..
Have you already confirmed there is a lack of 12 volts to the WUR when ignition is on? If you get 12 volts then the wiring is fine and your problem is elsewhere.

[ruf-porsche]

Originally posted by azasadny
Bobby,
Thanks! I'll take a look at mine today and se if I wired it up correctly. My car now starts and runs well, but stalls every time I'm at a stop, not accelerating. The car doesn't backfire or stumble at all, just idles slowly, then dies at evert stop sign. Looks like I have more adjusting to do.

Hey Art have you check the AAR?

No fast idle- To change the idle speed on a car with fuel injection you bypass air around the throttle plate, in other words make a controlled vacuum leak. If you don't have a fast idle take a look at the auxiliary air regulator, in a cold state you should be able to see through it. Check out all the hoses that have to do with vacuum for cracks.

Did you have anyone to set the CO for the car now that it is running?

[azasadny]

Bobby and ruf-porsche,
Thanks for the great info! I'll check everything tomorrow (no time tonight). I need to confirm power to the WUR and test the pressures to see if that's causing the problems I'm experiencing. I don't have an AAR but my idle speed "bypass" screw doesn't have any effect on the idle speed. My neighbor came over and looked at it and saw that the throttle "set screw" on the throttle microswitch was keeping the linkage from sitting a little higher and he turned the screw a little and now the car starts right up and idles at 1000rpm, and stays there even after it warms up. No more "hunting for idle". I get a pronounced "stumble" at 3500rpm and small backfires through the exhaust on heavy acceleration and I feel like something is holding the engine back. I've checked the plugs, wires, etc... and all seems fine so I'm thinking I still may have a WUR issue. I'll check Thursday PM and see what I can determine. Thanks again, you guys are great!!

[azasadny]

ruf-porsche,
I've just ordered a Gunson analyzer from a gentleman on theis board and as soon as it come in, I'll check the CO level. I haven't used a Gunson before, just set the mixture as bast I could by ear and feel. I'm going to test my pressures tomorrow to see if it's a WUR issue. I have apronounced stumble at >3000rpm and the engine feels like it's being held back...

[ruf-porsche]

Hey Art

Here's some info on how the WUR for your year car should be wired.

For the '73 CIS cars, the WUR got power directly from a fuse in the engine bay powered from the ignition switch. On the '74 and '75 the wiring diagrams show that the power for this relay is derived from the three diodes in the alternator that go to the charge indicator light. Starting in '76, the same relay that powers the fuel pump powers the warmup regulator. So only whenever the engine is running on the earlier cars, or when the fuel pump is actually running on the later cars, should you have voltage on the WUR (except for the '73 as above).

I had a Gunson analyzer one time until someone stole it.

[azasadny]

Ruf,
That's interesting because my alternator light is staying on and my battery isn't being recharged. I had to put a trickle charger on it after my 10 minute drive. The alternator was just rebuilt last week. I wonder if these things (WUR, alternator) are related? Thanks for the good info!!!

[ruf-porsche]

Art

Do your car have an external or internal voltage regulator?

If they rebuilt the alternator and your car has an external regulator you may need to replace the regulator. Normally when they rebuild an alternator with an internal regulator they replace the regulator at the same time they replace the brush assembly.

[azasadny]

Ruf,
My mechanic replaced my regulator with an external model and mounted in on the rear electrical shelf, next to the Bosch CD unit. He recommended the external voltage regulator instead of the internal one I had. An old car alarm system did some damage to the alternator and he replaced the alternator a few weeks ago. I haven't driven the car since I got it back from Ohio on 8/4 because of all of the problems I've been having. I'm going to either sell the car "as is" or replace the CIS with Zenith carbs, I think. I'm so frustrated and disappointed that I don't know what I'll end up doing... I swapped the engine (old one had pulled head studs), installed new clutch and clutch cable, etc... and I still can't drive the car and I started this adventure in eary June. Driving season is very short (as you well know) and it looks like I'll miss it entirely this year. I have spent more time on this board than I have driving the car...

[ruf-porsche]

Originally posted by azasadny
Ruf,
Driving season is very short (as you well know) and it looks like I'll miss it entirely this year. I have spent more time on this board than I have driving the car...

Yes the season is short. I drove my car twice this season, once to cruise with my daughter and once to take it for the biannual emission testing. I'll be wrenching this weekend to replace a very LOUD fuel pump.

If it was my car I would keep it with the CIS and not go to Zenith or Weber carb. My two Lotuses both have weber carbs and they are fun to tinker with. I think if you could get the CIS to work as it was designed to it would be a great car. My first PORSCHE was a 74 911. Very fond memories of driving that car with my then girl friend and now my wife.

[azasadny]

Ruf,
At this point, I'm more inclined to sell the car "as is" and then try to save up for a newer (like a 1987 911) car and try to put this bad experience out of my memory. I want to drive the car during the summer and do maintenance, common repairs, etc... This car obviously requires mechanical skills beyond what I have and that is something that I've realized recently.