Running rich

[jhhaas]

I have an 81 SC 3.0 US. The internals are all stock. I have updated to an MSD ignition and coil and recently have the distributor rebuilt. new fuel pump, fuel filter and had the fuel pressure set according to the manual. It has a 79 fuel distributor set up doing away with the computer, lambda etc.

So I have it on the dyno and it is running at 10.1 to 10.9 through most of the rev range at WOT. I took my 3 mm allen wrench and tried to lean it out but mostly it did not really effect the air fuel but it stopped running and became very hard to start after i apparently went to far. Please note that I did 1/4 turn did a pull and repeated 6 times going CCW each time. Eventually it would stall as I lifted and would not start. I wound it back and now it runs and idles but is running rich.

The A/F numbers moved maybe a point or two through the rather large adjustment.

Any suggestions? I read all about lean conditions but I could not find anything relating to my issue. TIA

[boyt911sc]

Originally Posted by jhhaas

I have an 81 SC 3.0 US. The internals are all stock. I have updated to an MSD ignition and coil and recently have the distributor rebuilt. new fuel pump, fuel filter and had the fuel pressure set according to the manual. It has a 79 fuel distributor set up doing away with the computer, lambda etc.

So I have it on the dyno and it is running at 10.1 to 10.9 through most of the rev range at WOT. I took my 3 mm allen wrench and tried to lean it out but mostly it did not really effect the air fuel but it stopped running and became very hard to start after i apparently went to far. Please note that I did 1/4 turn did a pull and repeated 6 times going CCW each time. Eventually it would stall as I lifted and would not start. I wound it back and now it runs and idles but is running rich.

The A/F numbers moved maybe a point or two through the rather large adjustment.

Any suggestions? I read all about lean conditions but I could not find anything relating to my issue. TIA

John,

Do you have the control fuel pressure data from cold start to warm condition? Knowing these numbers would give us a better picture. Plus have you tested and verified that you don't have any unmetered air gong into the system? What's the number on your WUR? Keep us posted.

Tony

[jhhaas]

I put the car back on the dyno. The air fuel at idle was 14.5 when I started and I ended up leaning it out to 15.0 at idle. The adjustment screw did effect A/F at idle. However, at full throttle, air fuel drops to 10 and basically stays there. No matter what I did to the adjustment screw, the full throttle A/F never changed. If I unplugged the WUR, A/F dropped to 9.1 at full throttle.

I feel like I am missing something (hopefully something simple).

the WUR number is 0 438 140 017

[boyt911sc]

John,

You car is an '81 SC USA model and should have a WUR-090. Could you post a picture of the WUR-017 installed on your engine showing the vacuum line connection? Are you aware that WUR-017 is completely different from the WUR-090 in many aspects? Keep us posted.

Tony

[T77911S]

you should use the 033 or 045 to match the fuel head. this also gives you the vacuum enrichment you need that goes along with the 79 head.

what did you unplug on the WUR?

what control pressure are you running?

[jhhaas]

I can try to take a picture later today but the hose runs from the top of the WUR to the lower nipple on the throttle body on the side facing the rear of the car (or me as I stand there staring at it). The top nipple is capped with a rubber sleeve. When I said I unplugged it, I disconnected the two wire plug on the top of the WUR. I also switched the hose and cap on the throttle body with no change.

There is no hose or plug on the nipple pointing to the driver's side frame rail on the lower left side of the WUR.

Thanks for your input.

T77911S,
I thought the '79 SC WUR was 089. Are 033 or 045 the Porsche numbers for the Bosch 089 and 090?

I do not have an O2 sensor or other 81 SC parts. The car was "backdated" to do away with that stuff because half of the components were missing and it was suggested this would be easier and cheaper....

I am thinking I need an 089.

[T77911S]

you need one with a vacuum enrichment. the 045 was used on the 79, the 033 on the 77 but both have the vac port.

[jhhaas]

Ok. Thanks. Will this lean the car out at full throttle? Oh, and the nipple on the side,should it be plugged or do I need to run a hose somewhere?

[boyt911sc]

John,

For your reference:

WUR-033......................for '76-'77
WUR-045......................for '78-'79
WUR-069......................for '79
WUR-072......................for '80
WUR-089......................for '81-'83 Euro/RoW
WUR-090......................for '81-'83

Decide which one you need and I'll lend you one. You don't need to buy it. Your expenses would be the shipping costs including the return-package. Take your time and PM me of your decision.

Tony

[jhhaas]

BOYT911SC

Thanks for the offer. The more I look at this the more confused I get. I look at the diagram below and I do not have the vacuum line in place. It appears that there should be a hose from the WUR to the thermo valve. The hose from the top of the WUR goes to the throttle body like it should but nothing is attached to the WUR where the "blue" hose is shown in the diagram.

[targa44]

For Tony: - hopefully related ques. for those of us with something diff.


I have a '76 Euro 3.0 ltr. engine. Which WUR should I have - same as '78 SC?

thanks,

[boyt911sc]

Originally Posted by jhhaas

BOYT911SC

Thanks for the offer. The more I look at this the more confused I get. I look at the diagram below and I do not have the vacuum line in place. It appears that there should be a hose from the WUR to the thermo valve. The hose from the top of the WUR goes to the throttle body like it should but nothing is attached to the WUR where the "blue" hose is shown in the diagram.

John,

You are looking at the diagram for a CIS '78-'79 USA California with EGR. The problem you are having is that you have a hybrid/mongrel engine using different parts from different model year. Your engine is a late CIS model with lambda (delete) using early SC fuel distributor. Your best option is to install the correct WUR for your FD. Since you are not utilizing the lambda system, you need a WUR with vacuum assist similar to the ones used in '76 to '79 CIS. At this point, some choices come to mind and they are WUR-o33, WUR-045, WUR-069 or WUR-089. What size intake runner diameter air box do you have on the engine?

Tony

[jhhaas]

Tony, thanks a million. Here's a pic for whatever it's worth.

[timmy2]

No enrichment control with the lower vacuum line disconnected...

[jhhaas]

...

[timmy2]

So, I assume it was just off for the picture. I can't read what is in the text block on my phone, even zooming .....

[boyt911sc]

Originally Posted by jhhaas

...

John,

So you are running the car with the missing line from the WUR? I don't have a WUR-017 in my inventory, so could you please post a side view picture showing the nipple connection. I like to see where the nipple is mounted (lower or middle section).

I would like to compare your WUR-017's configuration with those of the -033 & -089 shown in the above picture. Thanks.

Tony

[jhhaas]

There has never been a hose on the one in the pic. I did not remove it for the pic. Pic of the throttle body

The black hose in the picture is coming from the WUR and is going into the throttle body just near the return spring.

I'll take a pic of the side when it stops raining

[timmy2]

From just about everything I have read about setting the AFR for these engines (and how I have my megasquirt EFI set), you should be running around 13.8 at idle, 14.7 -15 or so at cruising speeds and down to about 12 or so at WOT. Lower the numbers in mid range a bit for power and less mileage...
My car runs great using those parameters and I look at the display a lot from my Innovate wide band set up.



Sent from my iPhone using Tapatalk

[jhhaas]

Here's a picture of the side.