How do you smoke test the EVAP ?
Disconnect the EVAP inlet line from the CPV (canister purge valve)....on 07-10 MY S197's (Ford changed the CPV design that removed the EVAP line connector port on the inlet CPV port.......this is still located on OEM original CPV's for 05-06 MY S197's.....that haven't already been replaced yet & install smoke detector output hose to the EVAP inlet line connector (or use an EVAP port connector to hook up to the 05-06 MY CPV EVAP port on inlet of CPV.........) if you can fab up a spare EVAP inlet line connector male insert this will be easier, but if you have a tapered hose insert you can wrap some electrical tape around it to help it to seal off against the connector's inner O-ring then wedge it into the EVAP inlet line connector to load up the entire EVAP system w\ smoke & air pressure.
You will want to use a self-contained smoke leak detector (has its own internal low-pressure 12v+ air compressor designed for testing EVAP systems) that also has an air flow meter on it w\ a metering ball to indicate the actual air volume being sent into the system........this is used to size up the severity of a leak when the EVAP system is fully closed up (ball should drop to 0 if no leaks are present) along w\ smoke to detect the actual leak (s) location(s) to make repairs.
Technically, you want to use a smoke tester that can use either N2 or CO2 instead of ambient air to test EVAP systems for obvious reasons (presence of fuel vapors.......), but these self-contained low pressure\volume testers can be used successfully as well.......just use a little common sense (no smoking or creating sparks.....) around the EVAP canister area during actual test period.
To close the EVAP system to pressure it up, you'll need a scan tool that has bidirectional control capability to actuate the EVAP CVS (canister vent solenoid) to close & seal system up.......or rig up a 30' harness w\ a rocker switch to connect to 12v+ power source then use blind box connectors to access the EVAP CVS thru the harness connector located in lft side of the EVAP canister to close the system up (PCM uses this CVS to run its EVAP test.....this solenoid is NO thus needs power to close it to seal the EVAP system to perform the pressure test.......just like the PCM does.
Send in the smoke w\ air flow & check the system while the CVS is NO to ensure that the EVAP air inlet vent line isn't restricted\blocked (should see smoke coming out of it w\ the air flow) then once this is verified, activate the CVS to close up the system then look for any smoke coming out of the system, starting from the inlet line at CPV thruout to the CVS......including the gas tank cap. Wherever you see smoke coming out, there is a leak that needs repairing..........bad thing is that Ford has discontinued selling the complete EVAP replacement kit for these cars, so you'll have to go aftermarket for parts........which will be scarce.......most only sell the EVAP canister itself, or EVAP canister w\ CVS, or CVS itself or the FTP sensor itself--splice in kit--but NO replacement lines or hoses thus McGuyvering is your only respite.....includes the junkyards for last resort....ie, Russian roulette on finding good EVAP lines on 12-21 yr old cars.........so be advised.
Here is the post of me actually doing this test on my car some 6 yrs ago:
https://www.s197forum.com/threads/lunati-voodoo-21270700-camshafts.136257/page-3# post 60
These EVAP systems are overlooked due to most folks looking for a MIL, but these can leak very badly before a MIL shows up & cause excessive air entry due to the EVAP outlet corrugated plastic line cracking allowing air to get drawn in bypassing the EVAP canister causing lean spikes into IM........especially if the CPV is also bad--this valve is NC so needs power to open. The seat in the CPV is the issue......if it is bad, the IM is constantly drawing excess air\fuel fumes (over purging the EVAP canister.......) that the PCM has to constantly try to account for, usually w\o success.........is the #1 cause of P0420\P0430 Catalyst Inefficiency DTC's from the excess air purge causing the rear cat O2 sensors to start tracking the front O2 sensors switching...........is also the #1 mistake most tuners & owners make when tuning these cars w\o checking these for integrity then shutting the EVAP system down in PCM\disconnecting from IM prior MAF calibration (will skew any MAF calibration as PCM will be running EVAP purge cycles in background).......nobody teaches or mentions this in any tuning materials that I've seen.........even Greg Banish.......no O2 sensor--even WB O2 sensors--can correct for this. This will throw the PCM off on catalyst monitoring\efficiency adjustments as well causing the same P0420\P0430 Catalyst Inefficiency DTC's as well as causing engine fueling imbalances........a LOT of good cats have been replaced due to these EVAP systems not getting properly checked\repaired or tested 1st to prove the cats have actually failed before spending money on cat replacement.
Hope this helps.
