Belpor

Hi,
I'm working om a 911SC from 1983. The car runs bad when cold small backfiring, runs to lean?

- I checked the vacuum
- set the valves
- Idle set at 900 RPM
- checked the timing with a timing light.
- Timing is good at idle bud doesn't enhance enough in higher RPM
- checked the vacuum by sucking on it. Doing that the rotor enhances. So its good?
- CO is at 2,5% any lower it runs bad
- spark plugs are new
- cap and rotor are new
- frequency valve is working

Replaced the O2 sensor tried to read it whith a dwell meter but no result!

What might be the problem with the dwell?? Or whats wrong??

Thnx in advance

Shannon123

Syphon gas out....put new gas in

Steve Weiner-Rennsport Systems

Check your control pressures, your WUR may be faulty.

TroyN

http://www.pelicanparts.com/911/tech..._Bosch_CIS.htm

There is a book by James Weber called Bosch Continuous Injection Systems that is very good but it appears to be out of print. See if you can find it as it's invaluable working on CIS fuel injection.

https://rennlist.com/forums/911-foru...-solution.html

Good luck! CIS is great when it's all working properly but can be a real PITA otherwise...

Peter Zimmermann

Does the car still have its catalytic converter? Did you check CO% out the tailpipe, or before the cat at the exhaust sample port?

Belpor

Hi all,

Thanks for the many replies!

To Shannon123: I allready but new gas in.
To Steve Weiner-rennsport system: I'll check my pressures next week and let you know. O, and waht's WUR?
To troYn: Thanks for the testing procedure, I'll use that
To Peter Zimmerman: I checked and adjusted the CO allready. The car has cathalytic converter.

ron mcatee

WUR = Warm up Regulator

Reiver

sounds like your wur...2.5 CO is pretty fat for a car running the Cat system so I doubt you are lean. It runs fine when warmed up?
Then prob the wur or a temp sending unit.

rusnak

You need a Bentley manual, a cis fuel pressure gauge, and a wide band air fuel meter

Peter Zimmermann

I know that. I asked if you measured CO% before, or after, the cat...

Belpor

I measured the CO after the cat..

Belpor

Ok, I don't have the right pressure tester. I'm going to buy P378 according to the Porsche manual. Its the same as vw1318:
http://www.mytoolstore.com/toolaid/diagn02.html
Or does anyone have better suggestions?

Belpor

Hi you all,

It seems very difficult to order the p378 (VW1318)
Does anyone have any suggestions? I have the meter and some hoses i only miss the threeway hose

Peter Zimmermann

Measuring CO% AFTER the cat tells you nothing. To set CO on a USA '83 SC:
1. Open the test port at the front of the cat
2. Disconnect the OXS wire in the engine compartment
3. Hook up & zero tester
4. Start engine and bring up to temp until the front oil cooler is hot to the touch; idle speed = 900 rpm
5. Check CO - use test port and be sure that the hose on machine cannot suck in outside air (hose should fit snug at test port and machine)
6. Spec = 0.4 - 0.8%
7. Adjust as necessary - always turn the wrench toward rich (clockwise) before moving toward lean. Never leave the wrench in the adjustment hole, or lean against the airbox, while checking/adjusting.

Connect the OXS wire, close the test port, and go for a drive. Now, if you don't have a good running car, you can begin to diagnose the problem.

Belpor

Hi Again,

The tester is on factory backorder until the end of August. Your
costs including shipping would be $200.75 USD via US Postal Service or
$241.25 USD via UPS

So, thats no sollution from mytoolstore.com....

Is there any other way to test the WUR?


I also replaced the O2 sensor and tried to read it with a dwell meter, no results at the testport. Anyone any experience with this?