Re: EVAP CANISTER VENT CONTROL VALVE

The systems vary by the yearmodel; thus I might need to swallow my words on this issue.... I'll try to check, if u tell u year model, engine type. e-mail addr on page below.

Basically no engine needs this circuitry; plugging it, and giving ECU ok -signal would keep problem checking system 'satisfied'. In Knock Sensor -bypass this is simple rewire =pull up resistor; however KS circuit is based on simple one sensor input.

Hi,

I followed your mod for the KS sensor. Have not had a KS code34 for

What do I need to do about the canister vent control valve?

Ken Davis

Hi again, forgot year & model

motor VQE 30 [DE]

Thanks again,

KD

I was checking the -96 EVAP circuitry schemas; quite a contrast to my 3gen nofrills EVAP... The 4gen (yours) employs multiple valves, one is stepper motor adjusted flow ctrl valve. The system takes ques from EVAP-pressure sensor, gas tank temp sensor, EVAP solenoid R, vehicle speed, rpm, airflow, O2 etcetc. ...so the EVAP logic in ECU is quite extensive. To bypass, I would try to add EVAP

-signal activated std relay causing bypass R2k resistance change to hoax that EVAP pressure sensor input in ECU. Bypass needs depend on the logic behind, possibly (?) no resistance change is not needed.

As I dont have 'the bits' I cannot test/verify the bypass, I have to eat my words... Thus I have to ask what is the actual problem? First thing in EVAP troubleshoot is to check for vacuum leaks, test valves separately, clean all, clean contacts. For the EVAP circuits, see/clic/seek on 'Favorite links' below; ...then you can read the pages from EC-215 EC-300, EC-182

...about the canister vent control valve?... The KS bypass was not actually my invention, found it on some discussion thread... very useful. As said, my guess is that EVAP pressure sensor input to ECU is the key issue: test try similar bypass with 2 to 3kOhm bypass resistor. I suspect it might need another R value at idle (no ECU-logic tables available as far as I know). That could be possibly done using a relay which would cut this bypass resistor always off at idle, thus leaving the pressure sensor connection as it is [at idle]. This relay control would be taken from from those EVAP valve solenoids ctrl wires.

I dont know how much leverage the gasoline tank temp sensor has in this EVAP. One may try installing 3k or upto 5k resistor bypass to its sensor input [like KS]; it just might be that these two tricks together would enable pluggin the whole EVAP issue to history. No way for me to verify at the moment...

As long as there is no direct +12V connected to the pressure/temp sensor 0-5V ECU logic inputs, playing with resistors pose no danger to ECU.