I am preparing to fire up my 3.0 and I have not been able to find anything that tells me where each of the wires goes on the harness and how it ties into the engine harness as well as the 914-6 relay board!
Any help is greatly appreciated!!
PS: It is a 1983 sc motor.
Full Version: Wiring A K-Jet FI Brain
Just guessing now, but that brain is Lambda Control .... operates the frequency valve(functionality is like the WUR)on the 3.0.
If you leave it out, the engine will supposedly run lean unless you somehow block it off on the engine (which is what I will do when I install a 3.0).
Otherwise, an O2 sensor in the exhaust, wires and power to the brain.
Not part of the actual engine harness in a conversion.
Other experts can now chime in .............
Just checked Bosch ESi and that is what it is .... Control for the frequency valve ...
If you leave it out, the engine will supposedly run lean unless you somehow block it off on the engine (which is what I will do when I install a 3.0).
Otherwise, an O2 sensor in the exhaust, wires and power to the brain.
Not part of the actual engine harness in a conversion.
Other experts can now chime in .............
Just checked Bosch ESi and that is what it is .... Control for the frequency valve ...
Thanks Slits,
I was planning on running the o2 sensor on this motor but if it is not nessary what would I have to do in order to "block it off at the motor"?
It has a large plug on the end of the harness as well as what looks like three more connection points. One brown ground, one red power and what I "think" is the sensor plug.
In the middle it looks like the two wires are red and red with a white stripe.
Then the brown ground cluster at the beginning of the harness!
If the brain is not connected (wired) to the engine how does it change the mixture?
I was planning on running the o2 sensor on this motor but if it is not nessary what would I have to do in order to "block it off at the motor"?
It has a large plug on the end of the harness as well as what looks like three more connection points. One brown ground, one red power and what I "think" is the sensor plug.
In the middle it looks like the two wires are red and red with a white stripe.
Then the brown ground cluster at the beginning of the harness!
QUOTE
run lean unless you somehow block it off on the engine
If the brain is not connected (wired) to the engine how does it change the mixture?
The "brain" receives a signal from the O2 sensor, which modulates the frequency valve. The frequency valve is on the backside of the CIS and piped to the return line to the tank .. I can't remember where it's supply is from but it modifys fuel pressure to the CIS injectors (from the fuel distributor) just like the WUR to vary the mixture being burned.
You could possibly cut it out of the system and solder the lines shut. At that point you would only have the WUR controlling modification of the fuel pressure sent to the injectors.
I would post the question to the Bird Board (Pelican Parts) in the 911 BBS section about removal of the frequency valve. That is where I read (I think) that not connecting will cause the engine to run lean.
Hope this helps you ... I have the same setup on a shelf (out of an '82).
You could possibly cut it out of the system and solder the lines shut. At that point you would only have the WUR controlling modification of the fuel pressure sent to the injectors.
I would post the question to the Bird Board (Pelican Parts) in the 911 BBS section about removal of the frequency valve. That is where I read (I think) that not connecting will cause the engine to run lean.
Hope this helps you ... I have the same setup on a shelf (out of an '82).
Thanks again Slits!
That helps a bit but not knowing where the signal goes to adjust the mixture is my problem!
I have figured out the o2 sensor but the harnes plug is my problem. If I could look at a 3.0 installed I could probably get a better idea how this thing fits into the system.
It looks like it plugs into the relay board and the motor plugs into the relay board but there is no info about how they connect together to adjust the levels on the motor.
That helps a bit but not knowing where the signal goes to adjust the mixture is my problem!
I have figured out the o2 sensor but the harnes plug is my problem. If I could look at a 3.0 installed I could probably get a better idea how this thing fits into the system.
It looks like it plugs into the relay board and the motor plugs into the relay board but there is no info about how they connect together to adjust the levels on the motor.
As stated, the brain is a standalone for controlling the frequency valve only. It has no other function. On a 911, it resides under the passenger seat.
Just as a WUR will bleed off pressure to the return line, so does the frequency valve. If my engine wasn't on the 3rd tier of pallet racking, I would shoot an image.
I do not know the internal construction of the frequency valve, but assume it works like an on/off bleed port, bleeding pressure to the return line to the tank. I do know that Bosch describes it function in terms of a "Percentage Duty Cycle". The O2 sensor, sniffing the exhaust, determines if the mixture is optimum, lean or rich. This signal goes to the brain and determines the "Percentage Duty Cycle" of the frequency valve.
CIS injectors are mechanical and can only vary the amount of fuel injected by varying the pressure they see. There is no timed open dwell time like an electrical injector.
I doubt you would find a useable pin to activate it on a 914/6 or 914/4 relay board. If I were hooking it up, I would merely run the wires for the O2 sensor and the frequency valve connector thru the center tunnel to the brain. Switched power for the circuit can come from the fuse panel.
Want to know more? Buy and read the book "Bosch Fuel Injection & Engine Management" by Charles O. Probst, SAE. It describes all the systems, testing, etc.
For wiring, you are going to have to pick up a diagram for a 911 and trace it out.
Just as a WUR will bleed off pressure to the return line, so does the frequency valve. If my engine wasn't on the 3rd tier of pallet racking, I would shoot an image.
I do not know the internal construction of the frequency valve, but assume it works like an on/off bleed port, bleeding pressure to the return line to the tank. I do know that Bosch describes it function in terms of a "Percentage Duty Cycle". The O2 sensor, sniffing the exhaust, determines if the mixture is optimum, lean or rich. This signal goes to the brain and determines the "Percentage Duty Cycle" of the frequency valve.
CIS injectors are mechanical and can only vary the amount of fuel injected by varying the pressure they see. There is no timed open dwell time like an electrical injector.
I doubt you would find a useable pin to activate it on a 914/6 or 914/4 relay board. If I were hooking it up, I would merely run the wires for the O2 sensor and the frequency valve connector thru the center tunnel to the brain. Switched power for the circuit can come from the fuse panel.
Want to know more? Buy and read the book "Bosch Fuel Injection & Engine Management" by Charles O. Probst, SAE. It describes all the systems, testing, etc.
For wiring, you are going to have to pick up a diagram for a 911 and trace it out.
Never mind I found the missing harness with all of the connectors on it!!
Thanks for your efforts Slits!!
Thanks for your efforts Slits!!
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