Post by ripcuda on Oct 8, 2007 13:18:34 GMT -5
Hi Gang,
Had a member ask me about vacuum lines on my car... so I took some pics and typed up some details. Just thought I'd share with everyone. Might be helpful.
Please let me know if any of this need corrected.
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'91 Justy EFI 4wd 5spd Vacuum Line Setup
Pic1 - passenger-side, looking at intake manifold (IM).
Pic2 - passenger-side, different angle.
Vac- line off IM - goes through one-way valve (black round) and plugs into plastic splitter that feed both solenoids (2wd/4wd).
2wd- line off 2wd solenoid (passenger-side) that goes to the tranny. On the tranny, it connects to the port on the driver-side.
4wd- line off 4wd solenoid (driver-side) that goes to the tranny. On the tranny, it connects to the port on the passenger-side.
MAP- line comes off IM through an orange one-way valve (on the IM) and connects to the MAP (Manifold Absolute Pressure) sensor bolted to firewall (can see in pic2).
A- line to "Fast Idle Control Solenoid Valve".
F- Fuel vapor line (comes from fuel tank) that goes to Fuel Vapor Canister (behind passenger-side headlight).
G- IM suction line from Fuel Vapor Canister (solenoid).
NOT VACUUM LINES
F-in - Fuel supply line. Fuel tank -> injector rail.
F-out - Fuel return line. Injector rail -> fuel tank.
Pic3 - passenger-side, above wheel-well, airbox removed.
A- line to Fast Idle Control solenoid valve. Solenoid bolts to bottom of stock airbox (seen in pic3)
B- line from Fast Idle Control solenoid valve to clean-air side of stock airbox (sucks air in when activated). Shown unattached in pic3.
Fuel Vapor Canister - black can-looking object. Two ports on the top plus drain on the bottom.
F- Fuel vapor line (comes from fuel tank) that goes to the center port on the Fuel Vapor Canister through a one-way check valve.
G- Suction line from IM - connects to lower port on the Canister Purge Control solenoid. When activated, IM can suck fuel vapors out of canister.
H- Feed line from canister to the Canister Purge Control solenoid - connects to upper port on solenoid.
4wd Transmission (selectable)
The 4wd tranny uses vacuum to shift from 2wd mode to 4wd mode. There's a large diaphram that actuates an engaging mechanism in the tranny. When looking behind the engine, below the intake manifold, this diaphram mechanism is the big, roundish looking thing farthest to the passenger-side, behind the axle (half-shaft). There is a vacuum port on either side of this diaphram. The 2wd vac line in the pics connects to the port on the driver-side, while the 4wd vac line connects to the port on the passenger-side. These ports supply vacuum to either side of the diaphram, thus moving the diaphram engagement mechanism in the tranny.
The two solenoids that control the vacuum both always have vacuum to them from the line off the intake manifold (mine goes through an orange check-valve). The 2wd/4wd switch just determines which solenoid is activated... thus sending vacuum through it's respective line to the tranny. Should the switch fail, you can manually hook up the vacuum line directly to either vacuum tranny line by just popping them off the solenoid and plugging them into the vac line.
MAP - Manifold Absolute Pressure sensor
This sensor takes the pressure reading (vacuum is negative pressure) from the intake manifold and converts it to an electronic signal the ECU can understand. ECU uses this signal (along with others) to determine proper fueling needs.
Fast Idle Control solenoid
Ever have a vacuum leak on your engine that caused the engine to idle higher than normal? That's all this does. When the ECU activates the solenoid, it creates a deliberate, controlled "leak". It sucks clean air from the airbox into the intake manifold causing a high idle.
Fuel Vapor Canister / Purge solenoid
As your fuel tank heats up and the gas sloshes around a lot, vapor pressure increases in the tank. Vapors have to go somewhere... and into the air is an EPA no-no. So vapors go through the line from the tank (F in pics) and into the canister through a one-way valve. Then at select times, your ECU says "time to suck out the vapors from the canister and burn them" so it activates the Purge solenoid and proceeds to suck the vapors in the canister into the intake manifold (through line H to the solenoid and line G to the IM) where the vapors are burned in the engine.
Had a member ask me about vacuum lines on my car... so I took some pics and typed up some details. Just thought I'd share with everyone. Might be helpful.
Please let me know if any of this need corrected.
-------------------------------------------------------------------------
'91 Justy EFI 4wd 5spd Vacuum Line Setup
Pic1 - passenger-side, looking at intake manifold (IM).
Pic2 - passenger-side, different angle.
Vac- line off IM - goes through one-way valve (black round) and plugs into plastic splitter that feed both solenoids (2wd/4wd).
2wd- line off 2wd solenoid (passenger-side) that goes to the tranny. On the tranny, it connects to the port on the driver-side.
4wd- line off 4wd solenoid (driver-side) that goes to the tranny. On the tranny, it connects to the port on the passenger-side.
MAP- line comes off IM through an orange one-way valve (on the IM) and connects to the MAP (Manifold Absolute Pressure) sensor bolted to firewall (can see in pic2).
A- line to "Fast Idle Control Solenoid Valve".
F- Fuel vapor line (comes from fuel tank) that goes to Fuel Vapor Canister (behind passenger-side headlight).
G- IM suction line from Fuel Vapor Canister (solenoid).
NOT VACUUM LINES
F-in - Fuel supply line. Fuel tank -> injector rail.
F-out - Fuel return line. Injector rail -> fuel tank.
Pic3 - passenger-side, above wheel-well, airbox removed.
A- line to Fast Idle Control solenoid valve. Solenoid bolts to bottom of stock airbox (seen in pic3)
B- line from Fast Idle Control solenoid valve to clean-air side of stock airbox (sucks air in when activated). Shown unattached in pic3.
Fuel Vapor Canister - black can-looking object. Two ports on the top plus drain on the bottom.
F- Fuel vapor line (comes from fuel tank) that goes to the center port on the Fuel Vapor Canister through a one-way check valve.
G- Suction line from IM - connects to lower port on the Canister Purge Control solenoid. When activated, IM can suck fuel vapors out of canister.
H- Feed line from canister to the Canister Purge Control solenoid - connects to upper port on solenoid.
4wd Transmission (selectable)
The 4wd tranny uses vacuum to shift from 2wd mode to 4wd mode. There's a large diaphram that actuates an engaging mechanism in the tranny. When looking behind the engine, below the intake manifold, this diaphram mechanism is the big, roundish looking thing farthest to the passenger-side, behind the axle (half-shaft). There is a vacuum port on either side of this diaphram. The 2wd vac line in the pics connects to the port on the driver-side, while the 4wd vac line connects to the port on the passenger-side. These ports supply vacuum to either side of the diaphram, thus moving the diaphram engagement mechanism in the tranny.
The two solenoids that control the vacuum both always have vacuum to them from the line off the intake manifold (mine goes through an orange check-valve). The 2wd/4wd switch just determines which solenoid is activated... thus sending vacuum through it's respective line to the tranny. Should the switch fail, you can manually hook up the vacuum line directly to either vacuum tranny line by just popping them off the solenoid and plugging them into the vac line.
MAP - Manifold Absolute Pressure sensor
This sensor takes the pressure reading (vacuum is negative pressure) from the intake manifold and converts it to an electronic signal the ECU can understand. ECU uses this signal (along with others) to determine proper fueling needs.
Fast Idle Control solenoid
Ever have a vacuum leak on your engine that caused the engine to idle higher than normal? That's all this does. When the ECU activates the solenoid, it creates a deliberate, controlled "leak". It sucks clean air from the airbox into the intake manifold causing a high idle.
Fuel Vapor Canister / Purge solenoid
As your fuel tank heats up and the gas sloshes around a lot, vapor pressure increases in the tank. Vapors have to go somewhere... and into the air is an EPA no-no. So vapors go through the line from the tank (F in pics) and into the canister through a one-way valve. Then at select times, your ECU says "time to suck out the vapors from the canister and burn them" so it activates the Purge solenoid and proceeds to suck the vapors in the canister into the intake manifold (through line H to the solenoid and line G to the IM) where the vapors are burned in the engine.