WHats this relay do?

[mb911]

WHat does the rectangular box next to the lambda brain and the frequency valve relay do. I am trying to track all possibilitys for surging problem when taking off.

Thanks
Ben

81 SC engine

[mb911]

I looked on pelicans catalog and nothing any help?
Ben

[targa80]

The frequency valve works in cojunction with the lamda control box and O2 sensor. The frequency valve varies the differential fuel pressure in the fuel distributor to compensate for a lean or rich mixture being sensed by the O2 sensor. The O2 sensor sends a voltage to the lambda control which varies the duty cycle (on/off) of the frequency valve.

Can you explain in more detail what you mean by surging when taking off. Do you mean the rpms cycle from say 1000 to 1500 at idle?

[mb911]

No it surges when you you are cruising at 2000-3000 rpms and does not seem to have very much power. Or at least not much for a porsche. I plan on checking fuel pressure today and post those numbers and maybe some one can help from that point. The little box that I am talking about concerns me because the frequency valve relay sat right next to it and was corroded beyond repair. The lambda brain is in good condition so realy the little box that is approx 2X1 is the one I would like to verify that it works or at least what it does? Any thoughts?

Ben

[mb911]

Ok fuel pressure is about 60 psi cold which is way over the 1.5 bar that it is suppose to have. Maybe that will help.
Ben

[targa80]

This is from the Bosch CIS fuel management book.

System K-Lambda
System pressure 5.0 BAR (73 PSI)
Lower chamber pressure 5.0 BAR (73 PSI) minus reduction caused by return of fuel at Lambda valve
Upper chamber pressure lower chamber pressure minus 0.1 BAR (1.5 PSI) spring pressure
Pressure drop at slit (system pressure minus upper chamber pressure) varies: 0.1 BAR (1.5 PSI) plus the reduction in lower chamber pressure
Enrichment method Increase slit size(by control pressure) increase pressure drop (by lambda valve)

I sent you a PM