Hey guys just like the title says. Where shoudl vaccum read at idle. Thanks alot
Matt
Matt
Evolved Member
mine reads at about 19ish for vaccuum. stock IX using a stewart warner gauge
Evolving Member
wierdest thing. my gauge reads 15 at idle, but the positive boost is correct. the gauge shows 21, and the datalog showed that is correct.
can't figure out why it's only -15 at idle.
gauge is an autometer.
can't figure out why it's only -15 at idle.
gauge is an autometer.
Evolving Member
My Autometer reads -15 as well...
Quote:
can't figure out why it's only -15 at idle.
gauge is an autometer.
Originally Posted by DahakaJR
wierdest thing. my gauge reads 15 at idle, but the positive boost is correct. the gauge shows 21, and the datalog showed that is correct.can't figure out why it's only -15 at idle.
gauge is an autometer.
Evolved Member
This can vary a great deal depending on altitude and cam selection. Pre cams I was routinely around 20-21hg now with cams it's down to 16-17hg.
Evolved Member
The Mitsu service manual states that the minimum limit for vacuum at idle is 15 in HG / 51 kPa. You're fine.
Evolving Member
it's cams like that guy said.
sometimes the cam makes the afr lean or rich. and when that happens, ecu compensates it by breathing in more idle air or dump in more fuel.
You'll see the vac go up and down as the afr changes on your wideband.
That's what I've noticed.
if I'm wrong, if you boost normal, you shouldn't really worry about vac, unless it's near the 0 at idle.
sometimes the cam makes the afr lean or rich. and when that happens, ecu compensates it by breathing in more idle air or dump in more fuel.
You'll see the vac go up and down as the afr changes on your wideband.
That's what I've noticed.
if I'm wrong, if you boost normal, you shouldn't really worry about vac, unless it's near the 0 at idle.
Silver Sponsor
Pulled from the shop manual
MANIFOLD VACUUM CHECK M1111002700387
1. Before inspection, check that the engine oil, starter and
battery are normal. Also, set the vehicle to the following
conditions:
• Engine coolant temperature: 80 − 95°C (176 − 203°F)
• Lights, and all accessories: OFF
• Transaxle: Neutral
2. Connect an engine tachometer.
3. Attach a tee-fitting joint to the vacuum hose between the fuel
pressure solenoid and the intake manifold plenum, and
connect a vacuum gauge.
4. Start the engine and check that idle speed is within
specification. Then check the vacuum gauge reading.
Idle speed: 850 ± 100 r/min
Minimum limit: 51 kPa (15 in Hg)
With cams your vaccum is going to read lower. Here in UT we se around 12-13is with cams.
Ben
MANIFOLD VACUUM CHECK M1111002700387
1. Before inspection, check that the engine oil, starter and
battery are normal. Also, set the vehicle to the following
conditions:
• Engine coolant temperature: 80 − 95°C (176 − 203°F)
• Lights, and all accessories: OFF
• Transaxle: Neutral
2. Connect an engine tachometer.
3. Attach a tee-fitting joint to the vacuum hose between the fuel
pressure solenoid and the intake manifold plenum, and
connect a vacuum gauge.
4. Start the engine and check that idle speed is within
specification. Then check the vacuum gauge reading.
Idle speed: 850 ± 100 r/min
Minimum limit: 51 kPa (15 in Hg)
With cams your vaccum is going to read lower. Here in UT we se around 12-13is with cams.
Ben
Evolving Member
In Colorado Mine reads around 15
In Illinois mine reads abou 19-20
I don't have cams, its the altitude/thin mountain air
In Illinois mine reads abou 19-20
I don't have cams, its the altitude/thin mountain air