Help Reading Vaccum Pressure
04-27-2007, 08:08 PM
#1
Intermediate
Thread Starter
Join Date: Jul 2006
Location: Los Angeles, CA
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Help Reading Vaccum Pressure
Suspecting a vacuum leak.
Can someone tell me what is the vacuum reading from the plugged port in the middle and top of manifold? It has identical pressure from the small port below. The small port goes to fuel pressure regulator.
Thanks.
gc
Can someone tell me what is the vacuum reading from the plugged port in the middle and top of manifold? It has identical pressure from the small port below. The small port goes to fuel pressure regulator.
Thanks.
gc
04-27-2007, 11:24 PM
#2
Rennlist Member
Join Date: Aug 2005
Location: Huntington Beach, CA
Posts: 1,353
Likes: 0
Received 2 Likes
on
2 Posts
Here's what the shop manual reads. "Special tool 9160/1" is a vacuum gauge that displays in bar.
Checking Resonance Flap For Operation:
When the ignition is switched on, the resonance flap is closed by vacuum action. When the ignition is switched off, the resonance flag is opened (rest position). The opening and closing noise is audible in the engine compartment.
Fuel System - Checking Vacuum System For Leakage:
General
If there are leakages in the vacuum system, the variable induction system may not operate correctly and there may be a reduction in engine power output.
Leakage Test
1. Run engine until operating temperature (70...90 degrees C oil temperature) is reached.
2. Remove vacuum hose from solenoid valve (fresh air/engine air) switchover flap. Attach special tool 9160/1 to open end of hose (on vehicles not equipped with a switchover flap, the plugged hose end is under the intake system). (This is up front on the left, attached to the heater blower box)
3. Start engine. Hold engine speed at 2500 rpm for about 10 sec. to build up vacuum.
4. Turn off ignition.
5. Test function of slide valve actuator. A second persion is needed for this work. Turn on ignition. As you turn the ignition on, the second person must observe the movements of the two levers on the intake pipe. If the levers are moved as the ignition is switched on, the slide valves and vacuum capsules will operate correctly. If the levers do not move, the vacuum system, the vacuum capsules or the slide valves may be faulty.
6. Pressure maintenance test on vacuum system. The ignition is still switched on. After the completion of items 3 and 5, the vacuum in the vacuum system must still be at least 0.64 bar. The pressure drop over about 3 minutes must be no more than 0.02 bar. If the pressure drop is higher, the entire system must be checked for mechanical faults.
7. After the test has been completed, reconnect vacuum hose to solenoid valve.
Checking Resonance Flap For Operation:
When the ignition is switched on, the resonance flap is closed by vacuum action. When the ignition is switched off, the resonance flag is opened (rest position). The opening and closing noise is audible in the engine compartment.
Fuel System - Checking Vacuum System For Leakage:
General
If there are leakages in the vacuum system, the variable induction system may not operate correctly and there may be a reduction in engine power output.
Leakage Test
1. Run engine until operating temperature (70...90 degrees C oil temperature) is reached.
2. Remove vacuum hose from solenoid valve (fresh air/engine air) switchover flap. Attach special tool 9160/1 to open end of hose (on vehicles not equipped with a switchover flap, the plugged hose end is under the intake system). (This is up front on the left, attached to the heater blower box)
3. Start engine. Hold engine speed at 2500 rpm for about 10 sec. to build up vacuum.
4. Turn off ignition.
5. Test function of slide valve actuator. A second persion is needed for this work. Turn on ignition. As you turn the ignition on, the second person must observe the movements of the two levers on the intake pipe. If the levers are moved as the ignition is switched on, the slide valves and vacuum capsules will operate correctly. If the levers do not move, the vacuum system, the vacuum capsules or the slide valves may be faulty.
6. Pressure maintenance test on vacuum system. The ignition is still switched on. After the completion of items 3 and 5, the vacuum in the vacuum system must still be at least 0.64 bar. The pressure drop over about 3 minutes must be no more than 0.02 bar. If the pressure drop is higher, the entire system must be checked for mechanical faults.
7. After the test has been completed, reconnect vacuum hose to solenoid valve.
04-28-2007, 02:10 PM
#3
Intermediate
Thread Starter
Join Date: Jul 2006
Location: Los Angeles, CA
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
epj993,
Thanks for the info. I ran this test and found no leak (vacuum holding). I suspect the leak is between check valve and intake manifold. I can read the pressure from the plugged port on top, but I don't know what are the correct readings in idle, 2000RPM or higher. If you or anyone can take couple of readings, it will be a great help.
gc
Thanks for the info. I ran this test and found no leak (vacuum holding). I suspect the leak is between check valve and intake manifold. I can read the pressure from the plugged port on top, but I don't know what are the correct readings in idle, 2000RPM or higher. If you or anyone can take couple of readings, it will be a great help.
gc