VIN 4519: 14-year "garage find"

[Rich_NYS]

Full Throttle (or WOT "Wide Open Throttle") Switch-
Disconnected, the B (Black) wire should show Ground and LG wire should have 12V, with key ON.
Closing the switch forces 50° - 60° CO Dwell, by grounding the LG wire, thereby enriching the AFR. This will change the engine's RPM/sound IFF the coolant is above 59°F. (Check warm because the Lambda Thermal Switch also forces the dwell to 50° - 60° when below 59°F...)

Black shows Ground
LG has 0V with key on.

Idle Speed Switch-
Disconnected, the B wire should show Ground, the BU and BLG wires should both have 12V, with key ON.

Black shows ground
B/LG shows 12V (Test light looked kinda weak, VOM shows 12V)
My switch doesn't have a BU, there's only 2 wires.
I hear a "click" somewhere [not from the switch] when testing the B/LG to ground, and when testing to Black(Ground.)


FWIW, I also tested at the plug to the ISM. The center had 12V, both outside contacts showed Ground.

[Rich_NYS]

Black shows Ground
LG has 0V with key on.




Black shows ground
B/LG shows 12V (Test light looked kinda weak, VOM shows 12V)
My switch doesn't have a BU, there's only 2 wires.
I hear a "click" somewhere [not from the switch] when testing the B/LG to ground, and when testing to Black(Ground.)


FWIW, I also tested at the plug to the ISM. The center had 12V, both outside contacts showed Ground.

Additional observations:

-ISM doesn't "vibrate." I connected a spare....no change.
-Frequency valve doesn't make a buzzing noise when jumpering the RPM relay socket (brown wire - white/red wires.)

[Bitsyncmaster]

Additional observations:

-ISM doesn't "vibrate." I connected a spare....no change.
-Frequency valve doesn't make a buzzing noise when jumpering the RPM relay socket (brown wire - white/red wires.)

ISM could be a bad connection or ECU may be bad.

Make sure your lambda relay is the proper type. That relay is not the same as all the other relays. A wrong one will stop the FV from buzzing.

[Rich_NYS]

ISM could be a bad connection or ECU may be bad.

Make sure your lambda relay is the proper type. That relay is not the same as all the other relays. A wrong one will stop the FV from buzzing.

I just came back inside to update; I swapped the idle ECU and the ISM vibrates now. The card started cold, but with a really high idle...gonna review a few things.

I'll check the lambda relay next.

Dave, safe to assume a carb conversion doesn't use an idle ECU, correct?

[Bitsyncmaster]

I just came back inside to update; I swapped the idle ECU and the ISM vibrates now. The card started cold, but with a really high idle...gonna review a few things.

I'll check the lambda relay next.

Dave, safe to assume a carb conversion doesn't use an idle ECU, correct?

There is no reason a carb could not use the idle system but I have not seen anyone do that yet. Not sure how well it would work.

[Rich_NYS]

There is no reason a carb could not use the idle system but I have not seen anyone do that yet. Not sure how well it would work.

I took the idle ECU out of my carbed car, wondering if I can run it without for now...

How do I know if I have the wrong lambda relay.....is it visibly different?

[Bitsyncmaster]

I took the idle ECU out of my carbed car, wondering if I can run it without for now...

How do I know if I have the wrong lambda relay.....is it visibly different?

The OEM lambda relay is a lower profile unit. Some relays show how the contacts are arranged with a schematic printed on the relay. A normal relay the center pin is normally connected to the power pin and goes open circuit when the relay is energized. The lambda relay has two pins normally open and both connect to the power pin when energized. I never could figure out why they used that special relay. I just rewired the socket so I could use the normal relay.

[Ron]

Roger that on the test light, I have one and will start using it instead of a VOM.

Clarification: "checking at the bulkhead...etc" referred to checking for corrosion/continuity if testing at the components showed no reading.

I didn't pressure-test yet; I found a few leaking coupler hoses (and air,) so I didn't bother. Once I know the system is thoroughly bled and not leaking, I'll pressure-test it.

Black shows Ground
LG has 0V with key on.

If it was warm, I would check the LG wire at the pin 6 (33 in chart) of the 7 pin White bulkhead connector. Otherwise, it is probably OK since the thermal throttle enrichment switch could be grounding it...

Black shows ground
B/LG shows 12V (Test light looked kinda weak, VOM shows 12V)
My switch doesn't have a BU, there's only 2 wires.
I hear a "click" somewhere [not from the switch] when testing the B/LG to ground, and when testing to Black(Ground.)

Unplug the Idle Solenoid and see if the click goes away.
Electrically, the BLG supplies ground for the Idle Speed Control Unit. The BU is tied to the BLG wire, runs to a capacitor and on to the Vacuum Advance Solenoid, supplying ground with the switch. (BLG-ISM is pin 6 (49) at the 9 pin White bulkhead connector...I don't remember where the tie is, physically.)

[Ron]

I swapped the idle ECU and the ISM vibrates now.

Damit, you were supposed to find that the BLG wire had no power first.

Good job!

[Rich_NYS]

I'm letting the engine cool so I can cold-start again tonight.

My cold start issue is no longer hard starting/wildly surging.....now it's high idle (2000.) Early observation: while at high/cold idle, the plate was cracked open a bit. After warm-up, it only opens when I rev the engine.