02 delete on '80 SC?

[C-Pierce]

OK wait a minute here, I think I can dig most of this.

AFR = Air Fuel Ratio
FV = Fuel (valve)?
WOT = Dunno this one

right,wrong?

thanks!! and keep going I still havent made up my mind....

Chris

[Scott R]

Originally Posted by C-Pierce

OK wait a minute here, I think I can dig most of this.

AFR = Air Fuel Ratio
FV = Fuel (valve)?
WOT = Dunno this one

right,wrong?

thanks!! and keep going I still havent made up my mind....

Chris

You got the first one, second one is Frequency Valve, last one is "Wide Open Throttle."

[C-Pierce]

Scott R - how does the frequency valve work? what were is it.

PS looks like I will have a similar set up as you sans the JE's

1980sc (US), 964 cams, SSis (or early boxes), 2 in one out.

Chris

[Scott R]

Originally Posted by C-Pierce

Scott R - how does the frequency valve work? what were is it.

PS looks like I will have a similar set up as you sans the JE's

1980sc (US), 964 cams, SSis (or early boxes), 2 in one out.

Chris

Starting with the 80' there is a fuel line attached to the back of the fuel distributor, and in-line with that is a modern day fuel injector to add enrichment. This injector has a 12V supply form the front relay and its grounded by the fuel enrichment computer under the passenger seat. For the 80's it was a pretty genius device.

[psalt]

Chris wrote,

how does the frequency valve work? what were is it.


Chris,

The FV is a pulsed injector used as a variable pressure restrictor for the fuel pressure in the lower chamber of the fuel distributor. All modern fuel management systems dither the mixture rich and lean of stoich for the benefit and life of the cat. The FV is an add on to CIS to allow electronic control of the mixture and, unlike previous CIS systems, the FV circuit must be pulsing in the mid range to get the correct fuel curve. I suggest you read the Bosch manual or Probst's book if you want to understand the system. If you have a dwell meter, you can get a start understanding the system by connecting to the test port and watching the duty cycle during cold start, open loop and closed loop after warm up. It will tell you if the system is working properly and allow you to adjust the mixture.

[tcar]

Originally Posted by Scott R

Starting with the 80' there is a fuel line attached to the back of the fuel distributor, and in-line with that is a modern day fuel injector to add enrichment. This injector has a 12V supply form the front relay and its grounded by the fuel enrichment computer under the passenger seat. For the 80's it was a pretty genius device.

When you say the ]frequency valve is on the 'back of the fuel distributor' do you mean the back? ... toward the back bumper?

Someone told me that it is supposed to buzz when the ignition is on. True?

[Gunter]

Originally Posted by Scott R

Starting with the 80' there is a fuel line attached to the back of the fuel distributor, and in-line with that is a modern day fuel injector to add enrichment. This injector has a 12V supply form the front relay and its grounded by the fuel enrichment computer under the passenger seat. For the 80's it was a pretty genius device.

If you mean the "Acceleration Enrichment Control Unit", it came in starting with the '81 year, not '80.
I understand the enrichment was done electronically effecting the FV, NO additional fuel injector.
There were additional components from'81 on; the CIS became quite complicated to satisfy emission control requirements.
The FV on an '80 has a different duty cycle than '81-'83.
They all buzz and you can feel it when the engine is running.
Back of the fuel distributor means facing the bulk head (Towards the front of the car)
Reading a book on the Bosch K-jetronic CIS will help to fully understand the system.

[Scott R]

Originally Posted by Gunter

If you mean the "Acceleration Enrichment Control Unit", it came in starting with the '81 year, not '80.
I understand the enrichment was done electronically effecting the FV, NO additional fuel injector.
There were additional components from'81 on; the CIS became quite complicated to satisfy emission control requirements.
The FV on an '80 has a different duty cycle than '81-'83.
They all buzz and you can feel it when the engine is running.
Back of the fuel distributor means facing the bulk head (Towards the front of the car)
Reading a book on the Bosch K-jetronic CIS will help to fully understand the system.

I suppose I did, maybe its for lack of better terminology, the FV is "controlling enrichment" in a certain way, however it may not be adding any under accel on the 80. Would that be correct?

[Gunter]

Yes, the '80 doesn't have the additional AECU plugged into the Ox Sensor Control Unit under the seat.
See psalt's excellent explanation below.

[psalt]

Scott wrote,

I suppose I did, maybe its for lack of better terminology, the FV is "controlling enrichment" in a certain way, however it may not be adding any under accel on the 80. Would that be correct?

Hello Scott,

No, all lamdba CIS models provide acceleration enrichment by going open loop after 35% throttle and reverting back to the fixed cold duty cycle (higher duty cycle, lower pressure, richer mixture). The 81+ refinement was to lower the fixed cold duty cycle spec and add a cold acceleration enrichment system that uses a temperature sender on the breather, another throttle switch and another control unit. Sort of a band-aid on a band-aid. This was to reduce emissions during cold warm up without a lean stumble on acceleration.

[Scott R]

Originally Posted by psalt

Scott wrote,

I suppose I did, maybe its for lack of better terminology, the FV is "controlling enrichment" in a certain way, however it may not be adding any under accel on the 80. Would that be correct?

Hello Scott,

No, all lamdba CIS models provide acceleration enrichment by going open loop after 35% throttle and reverting back to the fixed cold duty cycle (higher duty cycle, lower pressure, richer mixture). The 81+ refinement was to lower the fixed cold duty cycle spec and add a cold acceleration enrichment system that uses a temperature sender on the breather, another throttle switch and another control unit. Sort of a band-aid on a band-aid. This was to reduce emissions during cold warm up without a lean stumble on acceleration.

How does it know when its at 35%? The throttle position switch on the 80 is on off. It's not taking in a measure of degree of the throttle plate, and I don't recall a tach signal thats fed into the lambda unit.... Am I missing something here?

[psalt]

By design. The switch is a three terminal (3,18,2) black box on the back of the throttle body. The additional cold enrichment switch looks like the micro switch on an early CIS system and is over by the throttle linkage. It should be set to open at 15% throttle. The easiest way to test the main throttle switch is at the main temperature sender on the chain case.

[Scott R]

Originally Posted by psalt

By design. The switch is a three terminal (3,18,2) black box on the back of the throttle body. The additional cold enrichment switch looks like the micro switch on an early CIS system and is over by the throttle linkage. It should be set to open at 15% throttle. The easiest way to test the main throttle switch is at the main temperature sender on the chain case.

That switch does not exist on the 80' However on the 82 and 83 systems I have in pieces it is there. I had a feeling that what you were thinking of. The only throttle switch is the TPS on passenger side of the TB, and its either on or off.

[psalt]

Both switches are on/off, not continuous, they are positioned to open at different throttle angles. The 80 switch should be connected to pins 3, 6 and 2 on the control box and trigger the system to go open loop. If the switch you are looking at has only two terminals, it may be the micro switch from an 81. Take a look at the wiring diagram.

[C-Pierce]

yOWZA! I am going to look this all up in my bosch book.

I know where to come if I have running issues, which I am sure I will.

I still am not convinced of whether I should keep my o2 sensor or not. I have the capabilities to richen it up to 3% I believe it is?

Chris

[Scott R]

Originally Posted by C-Pierce

yOWZA! I am going to look this all up in my bosch book.

I know where to come if I have running issues, which I am sure I will.

I still am not convinced of whether I should keep my o2 sensor or not. I have the capabilities to richen it up to 3% I believe it is?

Chris

You can do that, but you're going to lose power. You can set it to 3.0 but it's going to move on you due to the frequency valve. I have a gas analyzer and I tried this, you will get walk. This was talked about a year or so ago and the consensus was you would have to get a ROW FD and everything else associated with it.

[C-Pierce]

probably wouldnt work if I unhooked the FV, and the o2...

eh?
Chris

[Scott R]

Originally Posted by C-Pierce

probably wouldnt work if I unhooked the FV, and the o2...

eh?
Chris

No, when the FV dies, or more commonly when the relay up front that powers it dies, the SC's run like crud.

[psalt]

Chris wrote,

I know where to come if I have running issues, which I am sure I will.
I still am not convinced of whether I should keep my o2 sensor or not. I have the capabilities to richen it up to 3% I believe it is?

Chris,

My advice would be to spend the $5 and fit a bung to what ever exhaust you choose. That way you can run the stock sensor, or fit a plug. Once you understand the system and see how easier it is to diagnose, check the mixture and adjust it, it will be much clearer. You cannot unhook the FV, it blocks the pressure line and leans out the fuel curve too much.

[Paulporsche]

Chris,

AFAIK all that stuff has been removed from my engine, and it runs great. The key may be to make sure if something is removed, then everything should be.(?)

I have a different , earlier style, WUR, one that allows WOT enrichment via vacuum.