Tripster

OK, here is what Ive got, By-passed the thermal time valve vavume line and results are the same, turns over for a while and then starts to chug a lug to life. I turned it off and pulled a plug, and as I knew, they are new. A little black sutt from idleing, but im sure it would burn right off when it warms.
Hot plug cold plug? You tell me,,,,,,
Denso # W24ESR-U

RarlyL8

W3 is the proper heat range for a turbo. Should use Bosch W3DPO platinum plugs (optimally). What is the gap on those? Should be 0.024

Tripster

Gap is .024 not .023
Also, just ruled out leaky cold start valve, I found a fitting that fit the fuel head and pluged off the cold start valve, same problem,,,,,

RarlyL8

Damn, I thought we were getting somewhere. Maybe we are, there aren't many components left!

How about fuel pumps? Can you use a Carrera pump (front) with a 930 pump (rear)? I know nothing of the Carrera pump characteristics and how it might affect the CIS system.

Tripster

I am not one to waste allot of time on a problem like I have on my hands right here, this has to be something very simple. So what I need to know is where can I get the information on this CIS, how every component works and when it should work. Some times you just need to go to the basics. Symptoms are as follows.

1. Very hard to start, then it chugs for 2 mins then clears up.
2. Will idle up at all, 5-6 K cold, then 1000 K warm
3. Runs great when warm.
4. Co has to be @ 8%, @3% it runs terrible when warm.
5. Drinks fuel, 8-10 miles per Gallon
6. Pissed off Carrera,,,,, and owner.

PorscheMD

What year of 930 motor did you install? Does it have a late model fuel distributor head that requires a frequency valve to be used with the oygen sensor control?

PorschePhD

A high CO to idle indicates too much pressure in the chamber of the fuel head thus causing the system to try and lean out. This is the purpose of the lambda control. It applies pressure or removes pressure from the lower chamber.

If the fuel head is silver then you need to introduce a frequency valve at apx 45% duty into the lambda control line, or send us the fuel head to be modified and rebore the internal ports open so you don't need the lambda control.

A black cast head will not have these issues as the internal differential ports are machined open. No external control is needed other than control pressure.

senna21

Cross reference for plug heat range:
http://www.globaldenso.com/PLUG/spec/index.html

Bosch K and KE Jetronic mechanical fuel injection system http://www.auto-solve.com/mech_inj.htm

PorschePhD

You can not properly cut a plug at idle on a turbo CIS car. They run to rich at idle in order to read correctly. The old way use to be to run it under WOT under full boost and shut it off. Pull to the shoulder and yank a plug.

Since wideband system have gotten cheaper this is not the best way to do it and it is far more accurate to use the 02 system

Tripster

Glad to see you guys chime in and help, always a plessure and blessing.
The motor is a 78 USA 48 state, the fuel head is Black.

Tripster

Fuel head

PorschePhD

That is a Euro head. No 02 control. Something else is going on. What are the system pressures and control pressures?

RarlyL8

The system and cold pressures were checked out the other day with the engine cold and the air temp ~70*F. Warm pressure was checked by starting the car and watching the pressure rise until stable.
System pressure = 5.6 bar / 82 psi
Cold Pressure = 1.4 bar / 20 psi
Warm Pressure = 3.0 bar / 44 psi

Are the '78-'79 USA fuel head and Euro fuel head the same? Neither has Lambda and both physically look the same.

How do the symptoms of a WUR gone bad manifest themselves? Does the bi-metal strip fail to bring pressure high enough when warm? Does the diaphragm fail as well? Are the spec ranges shown in the various manuals tight enough to be reliable 100% of the time for a system with 28 years of wear and age?

This engine "supposedly" ran perfectly when shipped. I have a suspicion that the WUR was swapped out, it does not look as clean and fresh as the rest of the motor.

PorschePhD

What is the WUR number? They are different.

On the heads, all 78-79 US cars had the Euro head. Only difference bewteen the US and Euro was DOT stuff.

PorscheMD

I am showing your system pressure should be 6.0 to 6.7bar. Your control pressure cold is good but a little low when warm. you should be at 3.65bar +/-.20. WOT should be at 2.9bar. I would set your system pressure correct first. Since I think I read earlier in the thread you are running two pumps but the front pump is off a na carrera I would check your fuel delivery rate. It should be at least 1500cc/30sec. Also, make sure you are getting power to the wur all the time. I would do these things as a first step then go from there.