idle vacuum in kpa. Running, hot engine held at approx. except only seeing -35 kpa vac at idle (factory spec -65 kpa) this on the stock gauge appears as the mark half way to -700 mmHg (factory spec should be -480 mmHg) would love to know what others with poncams are seeing. If we convert to inhg I get 29. I have 94 kpa in 800rpm btw , my car loss for about 40% power Thanks. On this example, it would be a good idea to plug off the idle air bypass and check again, if necessary. Normal sea level atmosphere is around 14. The vacuum inside an engine's intake manifold, by comparison, can range from zero up to 22 inches Hg . This is 55-69 kPa (8-10 psi) higher. Technician A says vacuum traces should be taken at idle, 1,200 rpm, and 2,500 rpm when using a pressure transducer. Therefore at idle, you're at 101. Vacuum at idle is always high and typically ranges from 16 to 20 inches Hg in most vehicles. then we can do it in KPa,milibars,inchs Hg or PSI. In the 30kPa range I could not run leaner than 13:1, the car would want to stall any leaner. Still my idle sucks if I go over 12:1 AFRs and I loose vacuum. 01 Kpa (1/100 of my reading) say that having a high MAP reading (102 kPa) at idle indicates a vacuum leak?. Engine vacuum (hg) = 30 - kPa * 0. The vacuum gauge should read between 51 - 74 kPa (15 - 22 in-Hg) depending upon the engine condition and the altitude at which the test is carried out. Thanks, "mostwanted" was getting on my nerves about being wrong that 18-22 in/hg, or 9-11 psi Even though a link I sent to him about vacuum reading said 15-22 is normal. The engine may run at that idle speed, but with 390 running a 224 cam on 110 in that 270H, it will. I would check the regulator first if this is the case. Idle speed now is 850 rpm in gear and jumps to 975 in Neutral because of the tight torque converter. One inch Hg equals a pressure reading of 0. Vacuum gauges typically display readings in inches of Hg (Mercury). Earth’s atmospheric pressure is roughly 14. With engine at idle speed, system fuel pressure should be 338 kPa ± 5 kPa (49. If not check the EVR solenoid for leakage. ITB's generally will have 65-85kPa idle vacuum, regardless of cam selection. Hg) at curb idle Vacuum hose connectedApproximately 230 kPa (67. Connect a vacuum gauge or equivalent to the intake manifold. The vacuum gauge should read between 51 - 74 kPa (15 - 22 in-Hg) depending upon the engine condition and the . they are zero referenced against a perfect vacuum. What is normal oil pressure for 5. 6 kPa (60-70 psi) for the KOEO fuel pressure and the fuel pump discharge pressure, 276 kPa (40 psi) for the low idle fuel pressure, 345 kPa (50 psi) for the high idle fuel pressure, and 20. While a 4AG isn't exactly a race engine or fitted with wild cams, I'd expect it to pull less vacuum then other low stress low RPM street stuff, but still be reading similar with ever other non-diesel/rotary on the road. MPG is probably just off because I keep messing around trying to find a vacuum leak that isn't there. ATM (standard atmosphere) PSIG negative gauge. 265 - 304 kPa (38 - 44 psi) At idle, vacuum hose disconnected. There are two basic types of MAP sensors: analog and digital. 0193 kPa (1 in-Hg) from the specified reading for every 304. It's much easier to hook up a vacuum gauge to a vacuum hose or port than it is to remove an O2 sensor. If your looking to convert psi to kPa go here. 265 - 304 kPa (38 - 44 psi) At idle, vacuum hose connected. I noticed with my set up that when the idle advance was up in the 18's 20's, then even with the idle valve all the way closed I could not slow down the idle below 1,050/1,100 rpm. 63 ish kPa if I converted it right it also idles at 900. 8"Hg and Cardo is at -19"Hg, which is actually 37kPa. In the meantime, check for vacuum leaks. 56*2 Auto tensioner rod depth (mm) Within 1 - Timing belt tension torque N×m 4. Doing the math, Baro kpa - MAP kpa at WOT = 98. The output voltage usually increases when the throttle is opened and vacuum drops. hg but was poorly sealed with a vacuum leak as I didn't have a perfect adapter to fit between the gauge hose and small diameter vacuum line. Run the engine at the specified idle speed. kPa Vacuum Gauges and Instruments | Engineering360 www. 49 Hg - which most definitely isnt. just installs into the left (front) valve cover. The idle is quite rough to the point where I cant get it below 650 rpm without taking a chance on the engine stalling. Mission accomplished and thanks to those who offered guidence. I looked at some logs of my previous setup, and they also showed around 60 KPA at idle, but I seem to remember the gauge showing around 16. Remember to check the idle in gear, to verify the kPa axis configuration above idle, is acceptable. In threewoods case, 46 Kpa would be around 16 in/Hg, if at sea level. Engine Management and Tuning - B16 Idle Vacuum Readings? - Can anyone provide me with an approximate value for vacuum, (MAP sensor reading) . - I THINK I have an engine mechanical problem (i. At idle, the vacuum signal was strong, causing excessive spark advance and making it impossible for this engine to idle properly. at idle my car is reading 38 kpa. or thereabouts Apr 5, 2004#4 Violater101Proven Member 1,021 0 Joined Apr 16, 2002 Originally posted by nine5raptor. For gauge pressure, atmospheric is considered zero, so when you're in vacuum, it's a negative number. I'm seeing ~80 kPa at idle, however during part throttle cruising I often see vacuum in the 30-40 kPa range. Here is what I am troubleshooting: I know that vacuum readings depend on. A high, steady vacuum reading is the sign of a healthy engine. 69 a tad high but within specs no need to mess with it. SwiftJet Car Vacuum Cleaner - New Model - High Powered 5 KPA Suction Handheld Automotive Vacuum - 12V DC 120 Watt - 14. Theres 2 kinds of engine vacuum. Jump to Latest Follow 1 - 19 of 19 Posts. My initial question is about idle vacuum and general idle stability. At wide-open throttle (WOT), atmospheric and manifold pressures become nearly equal as air rushes in to fill the engine's cylinders. After the 3 minute run time the engine should be idling normal. i think your ecu is showing you absolute pressure, not vacuum depression. if vacuum decreases as rpm's increase then there is a exhaust restriction. Thread: Someone explain the MAP/KPA correlation. Click to expand Should be -9 psi or 18 in. Engine vacuum tends to differ between engines and I'm unsure of how exactly this is determined. I've got 12v at the connector I can hear the solenoid click open -> I get vacuum flow when it clicks open ->. So, a few days ago, I hooked a vacuum gauge to a vacuum line. Choose a leaner AFR then what the TT cal is for idle and autotune the idle ve's for the leaner AFR and the problem should go away. To back up my replies, I connected a vacuum gauge and noted idle rpm vacuum. Additionally, I strongly recommend checking for diagnostic. 7 with an average map of 35 kpa at a warm idle and 49 kpa at a warm cruise @ 60 mph. it was originally reading in metric, kpa, at 35 kpa, I changed setting to imperial, at 5 psi, no code. Your idle pressure should be around 50 kPa on a well tuned engine with a modest performance cam in it. At idle, vacuum hose disconnected. Possible vacuum leak at the charcoal canister valve or the line leading to the canister in the right front fender area. The map in the ECU should read the same as the vacuum gauge, 100KPA - 33KPA = 67KPA Assuming on the intake manifold Adjust the map sensor settings to match the real life vacuum reading That cam should be able to 55 to 65KPA idle so with a little more tuning and careful setting of RPM etc the vacuum should get better 12-29-2021 #5 techmann52. You're going from 1% throttle to effectively 20-30% throttle immediately off idle, when used to you never needed more than 20% throttle to drive around!. There should be a magic number for vacuum, just like there's a number for compression - however like you said as long as they are all the same that's what matters most. A normal reading is typically 17 to 22 inches Hg. This is a stock new rebuilt 350, stock cam, Edlebrock 2101, rochester q-jet. 69 psi, so 9 psi is vacuum territory. What you could do is that rubber cap on the throttle body, it can be removed and a vacuum gauge hooked up. Connected a Scan-Tool to my OBD2 system and found out that my intake manifold absolute pressure is low at idle, reading at 36 kPA +/- 2. KPA inches of HG conversion. The volume that we will consider is a cubic meter, so V= 1 m 3, and the temperature is. Here is the correct thinking:Since psi is pounds of pressure per inch^2, you can't have a negative pressure reading in psi. Start the engine and check that idle speed is within standard value. International vacuum/pressure conversion table. Normal manifold vacuum on an engine running at idle speed is around 18 to 20 inches. I'm just using a cheap bluetooth scanner i actually found, connected to a few different apps. Unit, bar, N/cm2, kPa, atm, kp/cm2, m H2O, torr, mm Hg, in Hg, psi. what is your vacuum reading at idle in bars? thanks. Dave - With idle advance at 12/13 I get a MAP reading of ~50 kpa. Joined Oct 14, 2010 · 394 Posts. The fuel pressure should follow the vacuum down, and where it rests will just depend on how much vacuum your engine is drawing on the manifold. You're going from 1% throttle to effectively 20-30% throttle immediately off idle, when used to you never needed more than 20% throttle to drive around! Look at the throttle plate area, and by extension the throttle open area, compared to the single throttle you had before. With a running engine, intake manifold vacuum usually runs around 18 - 20 “Hg (inches of mercury). So I have a big cam, but I think I should be getting more vacuum then I'm getting. I think most vac gauges this will be in the 22 range on the scale but do the pressure conversion anyway. Finally, look at the last two columns. For the folks living above 10,000 ft. The needle on the gauge fluctuates between 15 "hg and 20 "hg vacuum at idle. Convert between vacuum units - torr, mm Mercury and psi. fuel type: lpg liquid/vapor or natural gas. Low compression, an intake leak or tight valves also can cause low vacuum at idle. I think you mean -14 in-Hg of vacuum at idle, though, not -14 psi. As the vacuum reading approaches 0, the KPA scale goes up, and reaches 100. The motor does have a rough idle and when it gets to about 1500 rpm it smooths out and runs strong. 400 kpa in full acceleration is 400 x. Starting the vehicle, assuming 20 in-Hg vacuum at idle, should create an idle reading of 9 in-Hg, 31 kPa, or 0. Fuel Pressure Test Connection - 4. Nevertheless, the values were good enough for posting. The engine did come from an automatic car and. If idle vacuum is 10", it will idle very rough. at idle what vacuum are you guys pullin ? im at 20 in does that seem of mercury (mmHg) or kiloPascals (kPa) below atmospheric pressure. 0 KPA of VAC would be at an absolute manifold pressure of 1 bar, and 80 or 70 KPA of VAC would be when a typical car is sitting there idling pulling maximum vacuum. If vacuum is steady at idle but lower than normal, the ignition or valve timing may be retarded. If/when idle speed increases, you've found a vacuum leak. This is installed along with a custom burnt chip, but it appears the vacuum is way too low and the MAP sensor is having fits. Intake Manifold Choice for EFI. A vacuum leak will often result in rough or slow acceleration because the engine will get the wrong air/fuel ratio when uncalculated air is entering or leaving the engine. Sorry that I do not have the actual figures in kpa. Vacuum at idle kpa vs inch/hg. For some racing classes, the engine must produce a certain amount of idle. Seafoam the engine, or motorvac if you can find a shop that still. Ok brains trust, this one has me stumped. ANVER Vacuum lifter capacities are normally based on 24″Hg (22″Hg for foam seals) at sea level per ANSI specifications with a safety factor of two (2) in the horizontal (flat), and four (4) in the vertical (upright). -Hg, but some may produce only 15 to 17 inches at idle. With an analog sensor, return signal voltage increases as the throttle opens and vacuum. 92 inHg) minus the vacuum pressure in inches of mercury. To me, this would indicate a vacuum leak. Technician A says that the exhaust system can be checked for restriction by using a vacuum gauge attached to manifold vacuum and operating the engine at idle speed. Intake manifold pressure during idle (gasoline). However, my vacuum gauge reads 14. MAP sensors measure absolute pressures. Initial timing refers to where the timing is set at an idle. 5:1 42mm CBR 1000rr ITBs, Bisimoto V2, Bluegrass Muffler custom stainless 2. Your desired RPM is 800 and you are idling fine at 800-825, MAP (vacuum) is good at 32-33 KPA. Converting between vacuum units like % vacuum - mm Mercury - psi - torr - micron - kPa. Wide open throttle = wide open butterfly = low resistance to air flow => manifold pressure is closer to atmospheric => approaching 100kPa. Use an adjustable vacuum test set (Special Tool C-3707-B) and a suitable vacuum pump to test the heater-A/C vacuum control system. Trouble is, my vacuum still sits around 10 psi. Thank you, Meep-Meep and Rebel. So I rechecked the intake vacuum pressure and now it reads about 62 kpa (18. Vacuum at idle should be around -18 to -20, and it should drop to -22 The map sensor reads in kPa (kilo pascals) from absolute pressure, . This measurement and calculation of mine is consistent with my mechanical vacuum gauge reading. If the idle is unacceptable, return the idle mixture screws to the highest vacuum setting, but in most cases this slight lean setting will still support quality idle performance. Manifold and vacuum connections aren't that much different in practice, at least in a stock motor. So both idle MAP and intake manifold vacuum dropped. Variation between Vacuum Gauge reading and MAP sensor. How is it measured? Vacuum is measured in inches of mercury (in. Shop for New Auto Parts at 1AAuto. P0131 and P0151 on 97 Chevy Express van. Like I said, I know for a fact it is the vacuum ports not creating enough vacuum. What does the vacuum do when you snap the throttle? Speaking of prius, I just replaced my 1st hybrid battery in a 2005 prius today. A MAP sensor that reads 1 or 2 volts at idle may read 4. I'd suppose that it depends on the size/number of the intake and exhaust valves as well as where you're tapping into the manifold to determine gauge vacuum. Which I take to be one atmosphere. The ECM will use known MAP sensor calibration values to convert the sensor signal voltage to an estimate of absolute pressure. What is normal fuel rail pressure?. You're going from 1% throttle to effectively 20-30% throttle . I re calibrated my tps sensor to be at 0. When testing intake manifold vacuum, a low steady reading at idle is likely to be caused by: The pressures before and after the isothermal compression are 150 and 300 kPa, respectively. Manifold vacuum is used to show engine compression and is created between the throttle plate and the intake valves. 100kPa of vacuum at sea level is near 0kPa pressure. When idling throttle position is %0, RPM is ~600 and the load is 25%. what does your trims do at 2500 rpm. The idle is fairly steady seems like +\- 80 RPM. I did reach in with needle nose pliers on the shaft and cycle it though. 1 in Hg 340 - 380 kpa @1800 rpm with Vacuum Hose connected 320 - 360 kpa at idle with Vacuum Hose connected 270 - 310 kpa with boost pressure above 32 kpa 350 - 350 kpa with Injector no 725 or B00. 2 L generally yields 47 - 48 kPa at 825 - 850 RPM idle speed. Holley Hi-Ram manifold 102mm DBW TB, Billet Atomizer 225s, tons of nitrous, blah blah. Normal atmospheric pressure is around 14. Idle relearn / throttle body cleaning. At WOT, your manifold depression isn't 98kpa (29 inHg), it's 101. however, i just installed my boost gauge and at idle my lex is . The method includes obtaining a request to determine inlet manifold pressure. Hg, the manifold pressure is about 10 psi less than the atmospheric pressure. Set your vacuum unit to kpa (options, settings). So with your measuring approach it would be a vacuum of 16. Using TTS Data Masters, the MAP reads 72-76KPA at what it likes to call an idle 700-900 (RPM). Using a hand-held vacuum pump, slowly apply 5-10 in. In summary, i have very low manifold vacuum which is likely caused by:. I'm running 10 deg advance at idle at about 13. My manual way intake vacuum should be at least -60kpa. As the LTFT increases with RPM I am leaning against vacuum leak. Hi all, I installed a Summit 1103 Cam in my 350, but the maximum vacuum at idle I can get is 13-14 inches. The vacuum jar has absolutely no pressure in it, so it becomes the absolute zero reference point. Although the amount of vacuum will vary by application, most will register between 15 inHg and 20 inHg (50 kPa and 70 kPa) at idle. vacuum/kPa) with an accuracy of + or - 3/2/3%. So at idle, you should see vacuum of at least 51 kPa or 15 in Hg, which is about 0. At idle, my MAP sensor reads 40kPa, which mathematically comes to 18hg. You need a lot of timing at idle 22-28, that helps a lot. At cruise 40KPa MAP, a loss of 60KPa, would be around 18 in/Hg. As you increase throttle these numbers drop, I . 23 bar) minimum inlet pressure: 30 psi (207 kpa) outlet pressure:-0. That would mean that 1 AW equals 52 Pa. These is related to all cars with no matter of size or power. With the air conditioning off, it would idle very smooth but with the air conditioning on, idle would bounce back and forth between 650 and 900 RPM. The trim numbers aren't bad per se, but i think there is a vacuum leak to troubleshoot. There will be pulses present in the vacuum. 2007 V6 @168K , 2016 Audi Q5 3. Start the engine and allow it to idle while observing the vacuum gauge. It uses a silicon wafer that is thinner in the center (0. Hg of vacuum to the MAP inlet, at this reading you should have between 4. Per the MS documentation, I tried squeezing the vacuum tube to create a restriction. Using a vacuum gauge to diagnose any of these symptoms can save you time — and money — when you have difficulty locating the problem source. Normally aspirated single carbureted engines will create between 15-22 inches of vacuum at idle or 50-27KPA. Fluctuations of 3 to 4 inches may point to sticking valves. Don't play with gauge in Hg and Megasquirt in kPa, this only end up in sheer frustration. At the top of Pikes Peak mountain in Colorado, which is more than 14,000 (4,267 m) feet above sea level, the baro pressure is less than 65 kPa. With gauge connected and engine idling as described above, increase engine speed to approximately 2000 RPM. Connect Rotunda Vacuum/Pressure Tester 164-R0253 or equivalent to the intake manifold (9424). Moreover, vacuum gauge also can give basic condition of your engine health. Next using a wideband o2 system tune the idle for best vacuum (lowest kpa) and/or for about 13. The lower the number the higher the vacuum. The vacuum at idle is quite high and enough to force a spit in a pipe or connection on a vacuum line, the extra air is drawn in and this air raises the rpm, as the rpm increases. WARNING: DO NOT ALLOW FUEL TO SPILL ONTO THE ENGINE INTAKE OR EXHAUST MANIFOLDS. With the engine running, intake vacuum should be at least 50 kPa. The Performance Diagnostic Procedures states: Enter 413. I does converts Kpa to Hg Absolute not Hg Vacuum or Hg Gauge. I just wanted to run it by you guys and see if 70kpa at idle will be an issue. Vacuum Pressure at Idle Speed: 24 kPa (180 mm Hg, 7. Normal manifold vacuum at idle for an engine in good condition is about 18 to 22 in. Vacuum issues with ITB? : megasquirt. Most vacuum gauges are graduated in inches of mercury (in. 92v o2 sensor, stinks rich out of tail pipe,. Then read off the vacuum gauge. For a naturally aspirated engine, the MAP scale is generally from 0-100kPa (kilopascal), 100 (most engines see 96-98KPa) being WOT. Unplugged my vacuum advance and plugged the vacuum port on the carb and then set the initial timing to 6 degrees advanced at 600rpms. Typical domestic vacuum cleaners can create suction of 20 kPa (Pascal is a measure of pressure that equals to pressure of 1 newton of force per square meter of area) – 20 kPa would be 20000 N/m2 or around 2 tons per square meter, or around 200 cm (80 inches) of water. At idle MAP read 32-34 kPa and will increase with engine RPM but highest value seen is 80 kPa. Throttle body calibrated, no vacuum leaks (in fact its wandering around 200-350 KPa, should sit around 400 so not a leak), o2 readings look ok. assuming you have high trims at idle only, try pinching or blocking the brake booster hose. So the (restated) problem is the following: If I start the engine when cold the engine starts and stays in failsafe mode (not just during the warm up period which is normal, but always) with rough idle. 7 in/hg Those are in absolute values. I have not put a vacuum gauge on as I don’t have one. What do the suction force values Pa, kPa or AW mean for. 206 - 255 kPa (31 - 37 psi) Residual pressure after 5 minutes. So I know big cams have really poor vacuum at idle. but to answer your question, I really doubt your idle issue is the vacum switch and if ya think it is simply pinch off the sense hose while its idling. Why is my park/idle vacuum different after I've driven around a bit? Does the increased engine temps change this? Do I indeed have a vacuum leak . The engine should now idle at the desired idle speed with the highest manifold vacuum. This is somewhere around 30 KPA. Note the log and see what kpa areas it idles at for the change. 0193 kPa (1 in-Hg) from the specified reading for. My latest thought is that its in the tune. Turn your air mixture screws out until you start to here or see (tach or vacuum gauge) the engine rev just a little and just when it starts to bog down a little turn in until max RPM is achieved. Vacuum is defined as air pressure below atmospheric pressure. The % of vacuum is a relative value where pressure at normal or standard atmosphere is the base value. Fuel pressure should be 294 kPa (42 psi) Disconnect vacuum hose from regulator and plug it. This example has 2 inches of vacuum. Pascal is a measure of pressure that equals to a pressure of 1 newton of force per square meter of area. A low vacuum reading means you have poor piston rings or oil rings. When you rev it up the vacuum increases (over 15 in Hg) . Idle pressure was about 70 - 80. Get a can of carb cleaner and spray check around carb base and intake flange areas while idling. The map sensor is reading vacuum/boost. My car idles at about -70 kpa, which brings the fuel pressure down to 230 kpa. The key to understanding how much fuel pressure will drop with vacuum is to convert "HG to PSI. My 93 Metro indicates 21" of vacuum at idle, if this helps you any. Emptied half a can of carb cleaner on all the vacuum lines I could find, plus IM and TB. Release and block the end of the probe several times to verify that the vacuum reading returns to the exact 27 kPa (8 in. If your Vacuum Gauge reads 20 in. Note that the 100 kPa column mimics a regular spark curve with timing all in by 2500 and 34* total. 100kPa of pressure is near 0 vacuum at sea level(and would actually be a bit above . You may have a problem if your VIN T pressure is less than 45 psi at idle or 55 psi when not running or with the vac line off the FPR. Once the idle RPM is brought above stock idle RPM, the vacuum advance will start to pull in anyway. Kilopascal (Kpa)is a pressure measurement unit. Steady low between 10-15 "hg vacuum: This reading indicates late valve timing. 2016 YXZ1000R SE 60th Anniversary Edition. Any pressure on the atmospheric side will push the flexible . When you adjust the timing and/or the idle AFR you shoot for lower kPa. With a lab scope a Manifold Absolute Pressure (MAP) sensor is measured under the following conditions: key on, cranking, idle, 2000 RPM, 3000 RPM and back to idle with an engine at operating temperature. Note the vacuum readings, and any fluctuations, at each speed. FWIW, a typical MAP (H-D may vary) outputs 4. 08 Hg - which is within a normal threshold for vacuum at idle on most engines. engine's are air pumps- faster it operates the greater the air flow through it. Yes, ECU commands a programmed set idle speed. This is a function of cam size, engine size, ignition timing plus carb settings. You should have a good 15 "hg vacuum with that cam. How do you explain the low compression at the MAP? It's a tribute to the computer fuel management that the car even runs with only 10 inches of vacuum. Which is where the MAP sensor (Manifold Absolute Pressure) is located, in the intake, behind the throttlebody, before the heads. With a running engine, intake manifold vacuum usually runs around 18 – 20 “Hg (inches of mercury). For robot vacuum cleaners, values of 4000 Pa are already the current upper limit - if the air duct is. kPa = bar x 100; mbar = bar x 1000 Vacuum Pressures Unit Conversions Chart (Relative) Perfect vacuum or 100% vacuum is a zero reference pressure. 92 inHg at sea level atomsphere pressure at 20 C/68 F temp. Basically the vacuum line is this "there" to provide a filtered vent to the FPR. Engines with drag race camshafts can idle between 4-10 inches of vacuum or 88-67 KPA. Your oil pressure gauge should not be more than a 100 psi gauge or the readings may not be accurate. Try using the bi-directional controls to vary spark and idle rpm to see where the car likes to idle. I didn't use scantool numbers yet. It is mounted with a perfect vacuum beneath the chip so that the air pressure from the other side flexes the chip. 30° BTDC is typical at a ported connection at 600 to 650 RPM. Last edited: Aug 31, 2020 Sponsors (?) stanglx2002 CT Material here. Winters PEM Series Steel Dual Scale Economy. During the diagnostic, I found MAP at 12-14 inHg pressure (16-17 inHg vacuum) at idle. The signal should be less than 1. The 500 and 600 columns were then to about 18 degrees. Do not allow the idle speed to exceed typical idle rpm. The fix here is to connect a vacuum gauge to the intake manifold and check intake vacuum at idle. MAF reading 39-42 g/sec at idle No smoke, engine does not sound labored. 3 adjust your idle to around 600 to 700 rpm, or as low and stable as you can get it. 20 kPa would be 20000 N/m2 or around 2 tons per square meter, or around 200 cm (80 inches) of water. A good engine will pull 3 to 5 inches of vacuum while cranking. dannobee: yup, engines w/higher-overlap cams reduce idle vacuum, and dialing in a bit more ignition advance typically increase idle vacuum -- that's why I asked about cam and/or ignition changes. at idle @ 850 rpms it sits between 45 and 50 kpa is this normal? I have no vacuum leaks all gaskets have been changed and idle is steady but if I tap the gas the revs hang for a bit. This is why you will, in many cases, experience a high engine idle RPM as one of the most common vacuum leak symptoms. Gauge reading was between 15-17in. The higher the cylinder pressure, the higher the vacuum. Years ago, a good friend introduced me to using a vacuum gauge to diagnose engine problems, in fact, it was often the first tool he would reach for when…. Then 101kPa - 37kPa, which is a MAP of 64kPa. Your vac seems pretty normal, anywhere between 24-35kPa is normal. #1 I'm tryin to get my car to idle properly. No lack of power in the midrange or top end. The T60 is a two stage regulator/vaporizer for LPG applications up to 60hp (45Kw). Vacuum hose disconnected289 - 309 kPa (85. If you're at altitude, these readings may be lower (supposedly by 1 inch of mercury for each 1000ft above sea level, roughly). thats a HUGE vacuum (double) over what it should be at idle. vacuum reading on idle While a 4AG isn't exactly a race engine or fitted with wild cams, I'd expect it to pull less vacuum then other low stress low RPM street stuff, but still be reading similar with ever other non-diesel/rotary on the road. PLACE SHOP TOWELS UNDER AND AROUND THE PRESSURE PORT TO ABSORB FUEL. 5 kPa FOR EVERY 500 METERS ABOVE SEA LEVEL. Check Your Engine's Health: With a Vacuum Gauge. What should the vacuum be at idle? Idle vacuum for most engines is about 18 to 22 in. -16 indicates a problem (likely a leak if you just had parts off and it was fine before that). Max vacuum is at idle, , as you open the throttle the vacuum decrease quite rapidly to almost zero at say 1500 rpm. Then tune the 'no-load' area just a bit. I can put up with the rough idle in gear for the time being. there should be more vacuum at idle than there is at WOT, close to none at WOT actually -1998 Tahoe. At sea level, atmospheric pressure averages about 1013 mbar or 101. For example, if the KOEO MAP reading is 29 in-Hg, 99 kPa, or 0. What You Need to Know About a MAP Sensor. What should MAP kPa be at idle? The MAP sensor is desirable to use because the absolute engine working pressure (vacuum) at idle and light load is unchanged by elevation. If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK. What is normal intake manifold pressure? – MVOrganizing.