Vacuum gauge flutter at idle. I will try that if all else fails.

A Jun 2, 2022 · My Mercruiser 7. It’s so Sep 1, 2006 · Manifold vacuum should increase slightly as the engine is held at 2,500 rpm at steady throttle. I wouldn’t tear into the engine though unless there were other symptoms. If the reading is still low, check for an exhaust restriction. (full manifold vacuum port) Turn the idle mixture screws out or in until you get the highest vacuum reading one at a time. When the transmission is put in Drive the fluctuations increase upto a 4" sweep. When you accelerate, it seems to level out and oil pressure is good, but will it will flutter again when you return to idle. Check all hoses, hose connections, and all open ports on carburetors and intake manifold are plugged. I used 36 deg total all in by 2600 rpm and 10 deg vacuum advance. When I say "flutter", I mean that it usually idles around 700-ish rpm, but you can see the needle jump around constantly, as high as 900 and as low as 500, causing the car Jun 24, 2020 · PCV valve will flutter at an idle. g - I have a stage IV cam). May 1, 2013 · What Ratwell is talking about is how to attach a vacuum gauge to assess the condition of the valves and some other components. Oct 26, 2003 · I was told that if the cam is bad that I should see the vacuum gauge flutter? I'm not really seeing any flutter idleing or driving. Apr 2, 2011 · You may need a vacuum pressure gauge with adapters (the manual says a constant manifold vacuum of 0. Jan 27, 2007 · Any time you see a rapidly bouncing gauge the first place to look is for a leaking intake valve for whatever reason be it the valve or spring. up front at the engine she'll start to gallop at idle with more advance. I already put in new sparkplug + cables. 0 " Hg. You write. A weak valve spring One of the easiest and cheapest ways to check an engine for serious issues is to use a plain ole vacuum gauge. At a low idle, the vacuum gauge flutters pretty bad. 17 in is good vacuum Feb 4, 2022 · 10 vacuum advance degrees added by full manifold vacuum, 24 IDLE degrees 14 initial, adding 22 mechanical advance degrees would give a TOTAL timing at mechanical advance rpm limit of 36 degrees. Stuttering/low idle/near stall/stall when stopped in gear 2. 8 m (1,000 FEET) OF ELEVATION ABOVE SEA LEVEL. RMTZ67 · Registered. Mar 13, 2012 · My R gauge flutters at load and seems to top out at 8-9 PSI at WOT. New Parts: Tank, lines, pump, pressure regulator, carb, cap, rotor, plugs, wires, coil, replaced all vacuum lines (and did the starter fluid spray test, carb adjusted to the Jun 3, 2016 · 1. I have a high performance 408 SBC stroker with a semi aggressive cam, so I did not expect big vacuum at idle. Idle speed now is 850 rpm in gear and jumps to 975 in Neutral because of the tight torque converter. 5/13” wavering back and forth, no matter what AFR I set the mixture screws to. Build app for android or IOS easily. Usually, vac- Nov 30, 2022 · 4. speed vacuum. not a lot of Boost gauge needle flutters only on low load in vacuum - '99 GC8 STI It's internet mechanics time! Looking for any nuggets of wisdom before I concede defeat and wait weeks for the stars to align to be able to get my car to a workshop. There are no boost leaks or kinks in the boost line [replaced it and the ferrules twice now trying to resolve, most recently two weeks ago]. Anybody know what would cause this? Jul 18, 2013 · and you have flutter you have a valve issue , sloppy guide or leaking valve seat at sea level minimum vacuum at hot idle is 20" not 19" but some vacuum gauges are a wee bit inaccurate . Monitor the vacuum gauge and make sure the idle is stable. Run the engine at normal operating temperature and idle speed A. Apr 14, 2016 · In terms of idle quality, this simple move from ported to manifold vacuum increased the idle vacuum in Neutral 2 inches from 13 to 15 inches Hg, and the in-gear idle vacuum is much more stable at nearly 10 inches Hg. 0193 kPa (1 in-Hg) FROM THE SPECIFIED READING FOR EVERY 304. Vacuum Leak. At idle the needle slowly goes back and forth from 16"-17" as the rpms go up and down a little. When the engine is running, the vacuum gauge needle will vibrate back and forth. Low vacuum also can be an immediate clue to a plugged exhaust. Then bring RPM up to 2500 and set timing at about 34 deg. Sunday we took it on a 200 mile trip. Dec 3, 2018 · Make changes that stabilize the vacuum gauge needle. k. 8/351M, 6. Jul 19, 2023 · When your engine vacuum gauge fluctuates at idle, you may have a worn valve guide or uneven compression caused by broken rings, leaking valves, or a blown head gasket in one or two cylinders. For some of the time on the first half of the trip the oil pressure gauge would flutter, but 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 performed. 88-11. Feb 8, 2015 · It turns out the fluttering PCV valve was acting like a vacuum leak! I think the lower vacuum created by the cam wasn't strong enough to hold the PCV closed at idle, which caused the fluttering and the vacuum leak. the gauge at idle bounces like crazy between 5" and 20". If I speed the idle up some, probably 900-1000 rpms, it smooths out and holds steady vacuum. Sep 9, 2019 · Diagnosing a vacuum leak can be tricky. 8 bar ; 10. There is no real way to draw a vacuum on a static engine for leak detection as one or two of the valves is always open somewhere, use the water in a spray bottle as SGK suggests while it idles and listen for a change in the way it runs, if you hear a change when you Nov 1, 2007 · I adjusted the distributor and carb using the vacuum gauge. The needle oscillates RAPIDLY at idle and does this anywhere up the RPM scale! At idle the average is at about 16 in. 1. Here is a video of the vacuum gauge at idle and with some throttle applied: Sep 7, 2015 · CC55, back to your concern since this is your post originally. Only show this user. Spring mechanical to hold steady at idle, should be 650-700 rpm's, and when degrees stop advancing, at the 36, limit should be between 2,800 to 3,200 May 10, 2003 · The fuel pressure gauge on my TY started to flutter a bit today. Does the vacuum gauge flutter or is it steady? It still could be the MAF sensor since fuel trims sometimes tend to be a little erratic. John SVO swapped turbo pinto, at idle the vacuum reading flutters about 1 Hg and smooths out when giving throttle. Feb 11, 2014 · Join Date May 2012 Location Charlotte, NC Posts 47 Post Likes Likes (Given) 4 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0 5 days ago · Before beginning any vacuum testing, a visual inspection should be made of the entire vacuum system. 0T Quattro 6speed manual 130k miles (Friend's car I help to maintain) Once your gauge is connected and seen to be registering a vacuum you can begin the tuning process (Normal vacuum at idle should be about 18-22In (4 Cyl), 19-21In (6 Cyl) or 15-18In on low compression engines ('In' is an abbreviation for inches of mercury)) Start by first warming the engine and note the idle vacuum reading Jun 4, 2002 · Just installed a vacuum/boost guage. I will try that if all else fails. 3 days ago · Unlock your engine's potential by mastering carburetor tuning with a vacuum gauge! This comprehensive guide explores common issues like rough idling and poor acceleration, delves into various carburetor types, and provides step-by-step instructions for optimal tuning. Oct 27, 2008 · You will always get the violent flutter if there is no damper fitted in the vacuum pipe. This reading corresponds to the reading on the cluster info center. Monitor your RPM gauge: Another way to diagnose a fluctuating RPM at idle is to monitor your RPM gauge on your dashboard. May 29, 2008 · while at Idle engine has about 14 to 15 inches Hg. Jul 31, 2006 · Cause of vacuum flutter at idle? Jump to Latest Follow 4K views 4 replies 4 participants last post by JayLo Aug 1, 2006 If vacuum drops intermittently at idle, one or more valves may be sticking open or dragging. 35psi boost gauge will be sufficient for your needs, unless you plan on going real big on the turbo. Jun 15, 2017 · After changing out my JLT filter from the oiled to the dry filter, I notice my vacuum gauge is not as steady at idle. Fast and easy way to try flutter in an online IDE. EJ25 - 2. Even when it flutters at idle, the oil pressure remains good. Apr 27, 2016 · I just performed this test on my car because I had the same vacuum gauge flutter at idle. It just flutters at stop lights/signs or sitting in a parking lot. It’s always possible that the fluctuation has to do with an engine vacuum leak, especially if it occurs while accelerating. HG. I've checked that the O-rings in the manifolds are seated. A vacuum gauge needle that vibrates rapidly at idle and then seems to smooth out with rpm can indicate bad valve guides or a bad cam lobe. Any ideas what may be the cause? 5 days ago · The Flutter gauges library includes a linear gauge and radial gauge (a. The side pipes make so much noise its not possible to use my ears and listen for issues. If your vacuum is dropping below the level that the valve normally closes that could be part of the problem. May 27, 2011 · Vacuum gauge isn't needed on a 6. Mar 15, 2012 · At 25 degree initial I end up with 34 degrees total and it's pretty spunky. read sweatons post in your original post Apr 6, 2020 · When i connect my vacuum gauge to my full vacuum port on the carb i get irratic vacuum readings between 13-16Hg. Engine serial# 0D390851 . Some fluctuation can be expected but it might be worth keeping an eye on. Oct 22, 2017 · Something seems amiss with those vacuum readings. May 13, 2018 · 360ci LA Mopar (iron headed street engine) 11. Worn valve guides C. We’ve said it before, but an engine vacuum gauge is an extremely valuable tool. Put vaccum gauge on and it tells me to chech timming or adjuct carb. We tested it from the turbo inlet. Jul 19, 2023 · I just got my car on the road. All engines when in proper tune and good condition will generate about 20" of vacuum at idle. Connect the vacuum gauge to a source of manifold vacuum. Sep 21, 2004 · I've got a freshly rebuilt engine from RPE. Here, we have idle vacuum of almost 10 inches with an idle speed of roughly 900 rpm. We also re-did the timing belt, nothing. Marine Quadrajet carb. When cold and in 5th gear but low speed of around 40 mph, the car actually bucked. 0T Quattro 8speed auto 100k miles (Friend's car I help to maintain) 2005. like a buzz so fast that the needle is a blurr. Mar 8, 2023 · If turning the idle mixture screws out (richer) does not improve idle vacuum or engine speed, then the leaner setting is always the preferred choice. 5 instead of 8 on the gauge. Jump to Latest 21 - 40 of 40 Posts. 5-7. ) To get started, hook the vacuum gauge to an intake manifold vacuum source. 6/400, 351 Cleveland - Timing and the vacuum gague - Good Morning, So this started as a typical bad idle/cold idle issue. Nov 30, 2013 · after you find the highest vacuum or highest idle rpm turn the mixture screws in i/4 to 1/2 turns. Engine and Exhaust. Normal vacuum at idle should be 19-21 inches for a Nov 20, 2005 · Finally got a vacuum gauge and plugged it into the vacuum port on my 351W's Performer RPM intake. Apr 23, 2003 · My motorhome (1990 460 V8, 77,000 miles, good UOA on 4400 mile Maxlife 10w30) has a mechanical oil pressure gauge I installed. If that's the case it sounds like you're reading the boost scale instead of the vacuum. 5L Turbocharged (2004-2013) Apr 17, 2001 · The following describes the actions of the vacuum gauge: Needle Fluctuated From 15-20 Hg At Idle - Sticking Valve or Ignition Miss Needle Vibrates Excessively At Idle, But Steadies As Engine Speed Increases - Worn Valve Guides Jul 2, 2018 · 1) The engine is a 225. ). Problem with 94 geo metro 3 cylinder manual. But as I said earlier, with this cam, don't be alarmed if the vacuum jumps around at low RPM. In most cases this will be a direct manifold source or possibly the PCV port (larger port) on the carb. Anyone else have this? Does this mean that I have a vacuum leak? The needle flutters at idle so much that it looks like I have two needles! Jul 27, 2015 · Virtually all cast base-plate carbs have a vacuum port (arrows) connected to the underside area of the butterfly to read manifold vacuum. a. 5-12. circular gauge) to create modern, interactive, animated gauges and radial sliders. May 8, 2015 · A vacuum gauge is an invaluable resource for tracking down engine issues. Power loss, rough idling, hissing car sound, low fuel efficiency, and car stalling are signs of a vacuum leak. First I unplug the line going to my cowl induction door and use that line. When I accelerate (not even getting into boost) it will flutter wildly plus and minus about 10lbs then settle back down to plus and minus 2 lbs. Your power valve is about the right size. Do the valve adjustment while the engine is running and open the adjuster until the valve continuse to clatter, then close until the clatter stops and then do the 1/2 turn. Any suggestions welcome, haven't tried to locate a vacuum leak just yet (carb spray or propane gas). The pointer on the gauge fluctuates rapidly but steadies as the engine speed is increased. 5 Audi A4 2. Now, anything off of idle in park causes the vacuum gauge to flutter so bad that it rattles. When cold, at light throttle input, a stumble/stutter around 1,700 rpm that almost felt like a transmission slip. Motor Mount. You can make your own damper by cutting approx 4 inches off the end of the vacuum hose then rejoining the two pieces of hose by using a piece of smaller diameter hose inside the vacuum hose. So I'm at a complete loss. As I said, though, this occurs very quickly, so the Apr 23, 2009 · As for the Mini "not having enough" vacuum, there is no flow through the gauge itself, just in and out of the connection hose/tube. If you put the same gauge on a v-8 it will be very smooth, on a 6 not bad and a little worse on a 4 but when you only have two cylinders the peaks are very sharp and slow enough that the gauge can react to them. OHS4 07-10-2014, 02:47 PM May 24, 2010 · try the timed vacuum if you can make this work, set initial timing incrementally upwards at idle until you develop a "flutter ", a slight flutter at the tailpipes at initial timing, idle speed. I locked out the ignition advance and checked timing, it's at 10 degrees. That's how a piston pump works. Jul 26, 2008 · Trying to adjust the idle mixture screws on my carb, so I decided to connect my new vacuum gauge to get the highest vacuum. We’ve put together this quick-guide to reading your vacuum gauge to help you identify potential mechanical or tuning issues more quickly. Stays at like 50-60 stable when I’m driving, but when I stop at the lights or so, it starts going a little crazy and wiggles from maybe 30 to 60. I call it "buzzing". Your Crown Victoria’s engine mounts connect it to the chassis. With pvc hooked up and timing set at 10 degrees and a 3. 75-0. Mar 31, 2016 · By measuring vacuum under different engine loads and conditions, you can track down problems within your engine and make the necessary adjustments or repairs. It drops about an inch and then goes back up, drops and goes back up. 5-18, but at 70mph highway cruise it drops to about 8. This can be an indication that there is a problem with the engine. Aug 15, 2023 · I’ve never set timing with a vacuum gauge but some people swear by it. now same gauge different pod it is reading about 17-18 (I say this because I see the needle between 15 and 20 . Oh btw Jun 23, 2021 · I recently installed PP dash gauges on my 2019 premium. Here's the problem, at idle the needle on the vacuum gauge flutters from 17-19 inches, but other times it's much rougher and the needle will swing back and forth a full 5 inches or so from 12-17. I used that exact cam in a '76 460 I rebuilt 20 years ago that I installed into an '82 F250 4x4 using "rebuilder" cast pistons and lowly 7. The magnitude of the flutter decreases as rpm increases, possibly as the needle simply can't respond fast enough. Mar 15, 2017 · Here are a couple vids of the fuel trim readings and also the vacuum gauge. Also starts are a little rough sometimes. it is either 17 or 18 . Joined Feb 20, 2008 Messages 1,555. The old rule of 2" lower than idle vacuum is incorrect. I just rebuilt the carbs on my '75 using a set of gauges I just bought. Also, cams with a lot of overlap make the gauge bounce as well as read low. Is Apr 11, 2018 · I was attempting to tune my 454 at idle using a vacuum gauge and i noticed the gauge would flutter between 8mmhg-10mmhg is this normal for a high duration cam or do i need to examine valves? Sent from my SM-G950U using Tapatalk Aug 18, 2008 · A fluttering vacuum gauge usually indicates valves not seating properly. Jan 21, 2018 · SVO swapped turbo pinto, at idle the vacuum reading flutters about 1 Hg and smooths out when giving throttle. Bouncing between 18-20 inches of vacuum. This is about the minimum size you should use. Noticed a little flutter in the vacuum needle it's about a 1 to 1. Today I was playing with VAGCOM and I Figured hey maybe I'll unplug my n75 and see what that does. See page 12 for idle mixture screws and curb idle screw location. Adjust to maximum vacuum on the gauge, both idle screws should end up at about the same number of turns out. . Usually, vac- Mar 12, 2012 · I have 12-14 inhg vacuum at idle which is at 850rpm. If I increase the idle rpm to 950, it increases to 14” and becomes steady. At 1200 rpm the the needle only bounces slightly. See full list on roadkillcustoms. I checked to make sure the filter was really tight. Of course the pulses are going to slow down as the engine is reved up. After researching it looked like most people were connecting the vacuum/boost line to the line right behind the throttle body that comes off the intake manifold. But I wouldn't call it a flutter. I did find a slight leak on one of the manifold lines and fixed that but I am still seeing the needle jump around. See Figures 2 and 9. The key is understanding what your gauge is trying to tell you. I hooked my vacuum gauge to my carb (manifold port) and the reading was bouncing between 11" and 15" very rapidly. Engine vacuum should be equal to or higher than vacuum at curb idle. 3. You have negative at idle and positive at cruise. The elbow will give the most accurate reading, sometimes when the boost is reading off the MAP line it can cause the needle of the boost gauge to flutter. The vacuum reading at idle is the normal 17. In about 10,000 miles it works fine. You could rig a vacuum gauge up to the valve opposite from the vacuum side and drive it and see how much you can accelerate before vacuum drops off. Jan 11, 2011 · I'm trying to get my idle mixture correct using a vacuum gauge and the vacuum gauge is jumping between 5 - 7 at idle. We just finished head rebuild here is what happens 1. Aug 31, 2015 · The vacuum gauges need to be connected to the inlet ports just upstream of the slide or throttle valve, and most bikes I’ve owned have had a convenient way of doing this, usually in the shape of a screw-plugged fitting in the carb itself (BMW) or on the inlet manifold (Moto Guzzi) or a vacuum pipe attachment on the carb (Morini) or inlet rubber (most Japanese multis, etc). Late ignition timing D. I've pinched off each vacuum line and sprayed carb cleaner Always remember that the vacuum at idle will also be lower at higher elevations such as during a trip to the mountains. Mar 6, 2023 · 4. My idle was 1200 in park and 850 in gear. (BTW is a mechinical and not an electricial gauge). if I pinch the hoses slightly they Aug 1, 2001 · Note the reading on the vacuum gauge. Aug 1, 2018 · Now, continue to slowly pump the MityVac until the rod bottoms out on the far end of the vac can. Higher-than-normal vacuum at idle is a common clue to overly advanced ignition timing, while low vacuum can indicate retarded timing. Billet base plates most often do not, so you need to drill the intake manifold and install a fitting. Oct 21, 2015 · I hooked up a vacuum gauge to my 289 4 barrel via a new manifold vacuum tree and got a steady 18 inches yesterday. The key is having a reliable engine vacuum gauge and then knowing how to read it properly. 2012 Audi A4 2. At 750-850 rpm it will move from 11. Aug 27, 2017 · When I learned to set the timing using a vacuum gauge a few years ago, I was told to take the engine to 2,000 RPMs and then turn the distributor to maximize the vacuum. The method many people use to adjust the timing with a vacuum gauge is to advance or retard the ignition until the highest steady This vacuum gauge is being used to observe what the manifold vacuum is on this 348 Chevy while Apr 10, 2013 · What could make a in dash factory 94 Caprice oil pressure gauge flutter, bounce at idle, looking at a 94 Caprice on a video and the oil pressure guage was bouncing up a bit but didn't see the car driven on video. Any concern here or is this normal/par for the course Starting with the engine at idle, slowly increase engine speed to 3,000 rpm. While I'm at idle, my vacuum guage flutters (reads 10-12 h. An interruption of the airflow in the exhaust system or your car’s intake manifold causes a vacuum leak. Slightly less flutter under WOT, gauge approaches -0 and flutters a few inches. Transform your ride’s Dec 21, 2022 · A vacuum gauge needle vibrates at idle is a common issue that can occur in many vehicles. It will close on acceleration. Hope this makes sense! Running vacuum test While performing a running vacuum test, it is possible to obtain a different gauge indication than that obtained under the cranking vacuum test. Your RPM gauge shows how fast your engine is spinning in revolutions per minute. Again, note the vacuum number on your gauge. 25 in. Sep 4, 2012 · Nothing really special, just a stockish rebuild with lots of torque, good driveability and a smooth idle in mind. Nov 5, 2013 · So I have been tracking down a misfire for what seems like ever. It has the stock cam + stock pretty much everything else, except electric fuel pump and regulator. vacuum gauge flutters at 18. Jan 3, 2007 · The gauge needle flutters very fast, so that it's almost a blur. 1 2. Today a new 2 inch vacuum gauge arrived which I am mounting in the car along with a tach. just keep Nov 1, 2011 · Ford liked to use carb vacuum to adjust the timing of yer dizzy. At this point, have a friend sit behind the wheel and place the transmission in Drive with his foot firmly on the brakes. it doesn't flutter . Jan 6, 2014 · Don’t know the cam specs or his idle speed and the definition of a “Mild Cam” is a little vague. If idle speed increases, lower it by closing the idle speed adjustment. At idle, the AFR gauge is the last thing to look at. Yer vacuum gauge can help you adjust for MAX idle rpms, (more inches of vacuum) NOT smoothest idle. Jan 6, 2014 · Engine will not idle. From what I just experienced this summer on my 350 I'd say you need to boost the idle up to 1000 and use a vacuum advance. Oct 3, 2014 · The amount of vacuum flutter/pulsation at idle is large making a precise vac reading difficult but a reasonable measured average vac is around 6. The best way to determine if your idle air control valve is the issue is to check Dec 30, 2008 · A timed port on the carb has NO vacuum at idle, that is why it is called a timed port . Compression is 190 across the board. What you're wanting is a vacuum can that will be "all in" at idle. If vacuum at 2500 rpm is less than idle vacuum, disable the EGR system and retest. Above 1k rpm it smoothes out nice and steady. At 2500 rpm in Neutral, the normal high-speed vacuum reading should at least equal idle vacuum. 4. Apr 8, 2018 · The problem has continued and I finally decided to hook a vacuum gauge up and see what I got. I have a boost gauge installed and before I was getting -20 psi vacuum at idle and be able to hit 15lbs of A vacuum gauge is connected to the intake manifold of an engine running at idle. The only change was moving the vacuum on the distro to the intake manifold. Good, steady vacuum around 20" at idle. and set your idle rpm around 650 rpm in drive. Then set you idle and idle mix. When using a vacuum gauge, it is important to understand the behavior of the needle and know what the reading indicates. Aug 20, 2022 #9 hensleyt Well-Known Member. Under what conditions should the Oct 18, 2011 · I have a 2002 Silverado Z71 pickup. You might notice RPM fluctuation, as well as reduced fuel efficiency, the Check Engine Light, a rough idle and a hissing noise. May 5, 2020 · Give enough advance to get the car started and set the idle screw around 800RPM and dist advance until it idles smooth and let warm up. I'm pulling the measurement in the line between the boost retard and the manifold, and the gauge is a cheap one, so this might be a potential cause of the erratic measurements in and of itself. Sep 2, 2023 · My oil pressure gauge flutters when I leave the car idling. Vacuum leaks. Oh yeah, when you open the throttle quickly vacuum should drop momentarily then come back up, not the other way around. As the diesel engine does not produce enough vacuum itself, the next thing to look at would be the vacuum pump (please take a shot at the other end of the thick black tube). Has developed a rapidly fluctuating vacuum gauge needle between 19 and 21", at idle speeds upto around 1000 rpm. Upon warm restart, engine idle would drop below 500 rpm and almost stall, 3. Idles pretty steady at 600 rpm Apr 22, 2010 · I was setting the idle mixture on my Quadrajet the other day using the vacuum gauge method, and noticed the gauge fluttering very fast within a 2-3 in/hg range (15-18 in/hg). I'd say no richer than 13:1 at idle. Jul 24, 2021 · Connect your vacuum gauge and adjust the idle screws in and out noticing what the vacuum gauge does. (Figure 6) A steady reading between What causes vacuum gauge flutter? A vacuum gauge needle that vibrates rapidly at idle and then seems to smooth out with rpm can indicate bad valve guides or a bad cam lobe. At idle it reads between -15 to -20inHg and under light to moderate acceleration floats around 0-4 PSI. If you’re noticing that your RPM are constantly going up and down, even when you’re not accelerating, it’s likely that you have a bad idle air control valve. A vacuum gauge can tell you a lot about an engine's condition, similar to a full leak down test - but in a much easier way. You adjust the timing to maximize the vacuum reading. Aug 1, 2018 · Is the reason the vacuum advance reconnect doesn't change the idle because the 10" of vacuum (and fluctuating rapidly) is not enough to pull the advance? Where should I start troubleshooting the fluctuating vacuum and should it be closer to 20 at idle? Nov 17, 2009 · I'm with Cobalt. Hooked it straight to the same port and same pipe as the external gauge and get a reading of only 11 inches! Jul 14, 2016 · The best way to know how well your car idles is to use the combination of a tach and vacuum gauge. . Sep 16, 2008 · When I got my turbo, my boost maxed out at 10. This should give a greater vacuum at idle. , sounds like you have a vacuum/boost gauge. Next, turn one idle-mixture screw in -turn and note the change on the vacuum gauge. At night or in a very dark garage with no light, open the hood while the car is running. Above 1000 rpms, it's "rock" steady. Vibration- and Corrosion-Resistant Vacuum Gauges Designed for harsh environments prone to vibration, these gauges pair a corrosion-resistant 304 stainless steel case with a glycerin-filled dial to reduce needle flutter. This will raise idle speed, which needs to be reset as it rises. (Note: Some cars also have vacuum operated heat/ac controls. The oil pressure gauge has started to flutter when at idle. Sep 23, 2008 · The flutter comes from the fact that you have a two cylinder engine. That cam, degreed "straight up", made just about 19" of vacuum @ 800 idle rpm(in Park/Neutral). You want it to be about half of the idle vacuum or slightly above. Its bouncing so fast I can barely see the needle. "Will start fine, then at idle will pop and misfire intermittently out of each exhaust - random misfire". I have the gauge fluctuating between 15-20 in Hg at idle. I grabbed a handful of valves off the shelf at the parts house and tried different ones until I found one that stayed closed at idle. That's how fast it moves (8-15"). I had to use a 3000 converter to make it all work right. MPG mileage seems about normal, no DTCs, starts fairly normal, just has a rough idle and hesitates on heavy accelerations (noticeable as of late). The method many people use to adjust the timing with a vacuum gauge is to advance or retard the ignition until the highest steady This vacuum gauge is being used to observe what the manifold vacuum is on this 348 Chevy while Aug 14, 2014 · Secondly, I think you'll find that it's pretty typical not to have a smooth vacuum needle at idle on a 4 cylinder engine with valve timing-overlap, and the fact that at idle you're really only "sucking" 350 times a minute or about 6 intake "sucks" a second - that's about what your needle is showing, and it smoothed out nicely at higher RPM. BLT, no leaks but pressurizes the crank case alot. Jul 9, 2005 · Probably due to power valve opening/closing as vacuum fluctuates about 7" as another poster suggests. 56 rear end the engine feels really strong. Feb 27, 2015 · Also the oil pressure gauge will flutter and go lower but even though I know its kind of a dummy gauge it worries me so I shift into neutral at lights and give it some gas. If the vacuum reading increases—say, from 14 inches to 14- inches—move I know is no gauge fault just mechanical is more accurate , anyway one no proper working injector can made flutters on idle and also no stable afr when u drive car under vacuum . Aug 29, 2023 · Bad Idle Air Control Valve. To check further, run the engine at about 2500 rpm for Jan 19, 2022 · My idle was wonky and the vacuum gauge would flutter at idle . There is no flutter at full throttle (flat on the zero vacuum stop), nor at closed throttle on over-run (15"Hg to 20"Hg depending on rpm/road speed, gradient etc). I switched hoses to the right side and then those flutter so I know it's no the gauges. Here’s a good YouTube video on how to do it. and while holding the RPM at say 2000 or 2200 or any other elevated RPM the needle continues to keep that blurr or vibration. The left bank (2&4) gauge arrows flutter. At 2500 rpm in Neutral, the normal high-speed vacuum readingshould at least equal idle vacuum. This also has caused my car to not hit boost target and to also not have proper vacuum. It increased to 20" when I gave it a bit of throttle. Nov 20, 2009 · I advanced the timing to 12 degrees, readjusted the idle mixture screws and now I have about 13-14 inches of vacuum with the idle set at 650 rpm. A bad idle control valve can also lead to fluctuations in the RPM. Dec 11, 2016 · Now adjust curb idle screw until you get an idle of 800 rpm. Just use the vacuum gauge as you dial-in the idle mixture and static timing, and try to tune for the best vacuum you can get at idle in park and in gear, and you'll be fine. Anybody know what would cause this? Flutter editor online. The problem I've noticed is, at an idle, the vacuum gauge is fluttering sooo fast you can't read it. An engine vacuum leak is another probable cause of a vehicle’s RPM fluctuation. A leaking intake manifold gasket B. Use these gauges with vacuum pumps, packaging equipment, and in suction lines to measure and display vacuum. When there’s a vacuum leak, the engine’s air supply gets interrupted. vacuum the needle vibrates somewhere between 13 and 14 Hg consitantly. There are a few things that can cause the vacuum gauge Re: Fluctuating vacuum gauge at idle 12-23-03 11:53 AM - Post# 359382 In response to bheisner Sounds like a valve isn't closing while running. - I turned my truck on and checked the vacuum after about 1 minute of running, got a steady 18 inches of vacuum at idle. Connected to brake booster hose to intake manifold = Flutter Connected to manifold vaccum port on carburetor = Smooth For me, this was a good discovery. Download your app and run it. ride tight to that flutter point, stay right at at, just under it. , and it fluctuates between about 16. 4 454 vacuum reading seems low, and the needle flutters *I think* like it has worn valve guides. If they wear out, it can cause a shaking condition when idle. 3:1cr. 2. Always remember that the vacuum at idle will also be lower at higher elevations such as during a trip to the mountains. 61 PSI). At snap throttle, the vacuum gauge should plunge to zero and then increase at least 25% above idle values as the throttle is snapped closed. Mar 12, 2011 · Vacuum gauge flutter. Your leak may even be on the vacuum gauge side of things (like the vacuum actuators with your HVAC) Mine was like yours a year ago, did not effect the idle or the engine performance in any way. Start by first warming the engine and note the idle vacuum reading. Looking at your vacuum and comparing to mine, it is not that bad. On this Mar 19, 2010 · It is critical that you record the readings while the vehicle is stuttering and while smooth, and keep those numbers separated and titled with conditions. leaning up the idle mixture slightly wont hardly effect idle quality but emissions and fuel economy will improve. Shakes when idle, smooths out while driving, thunking sound when shifting, no code. PIDs- Nov 4, 2020 · If your vacuum canister doesn't start adding timing at low enough vacuum, you can have a situation where the amount of advance it does add fluctuates at idle, which in turn makes the idle speed, and therefore vacuum, bounce around. I've never had this issue before. Best idle AFR will depend on the engine (cam size, idle rpm, etc. When the guides are this worn, the engine will have a serious oil consumption problem. May 11, 2020 · 335 Series- 5. It could have a leak into the valley - common on intake swaps. Only 14 inches of vaccum. The bad guides allow the valve to move around a bit while the valves are at their lowest opening point, and the bad lobe will effectively kill that cylinder at low lift. the flutter issue is much more important if vacuum gauge is connected to the purge line move it to the position as directed above Aug 4, 2005 · The needle doesn't flutter it was about 20 vacuum before I swapped gauge pods . at acceleration the needle keeps the same blurr. But as soon as I touch the throttle, the needle stabilizes. If I open the throttle quickly and let it go ,then vaccum will rise to about 21 inches then drop back to 14 inches. Build flutter apps online. Aug 28, 2005 · Going from 14 inches @ idle to 19 off idle indicates a problem, if there are no vacuum leaks do a cyl leakdown test and check the plugs for oil. Shoot with a timing light at idle and then tell us here degrees its idling. In just 3-5 minutes you can know if an engine is healthy or not. May 11, 2005 · The instant you let off the gas and the throttle plates close, vacuum will return. I'm running the summit 2801 cam and my heads were rebuilt last year. Plug your vacuum gauge into the lowest port on the left side of carb. An air/fuel ratio meter can also help, but don't fall into the trap of Jun 20, 2022 · I’ve always noticed my engine has a fluctuation in the vacuum reading at idle. Sep 26, 2013 · From what I've read, I understand there should be vacuum indicated on the boost gauge while in idle. So, if your idle vacuum is only 11*hg then you're going to want a vac can that is completely pulled open 2 inches of hg before that, or For example, if you see a code like P0507 (Idle Control System RPM Higher Than Expected), it may indicate a problem with your IAC valve. May 12, 2009 · Er, a vacuum gauge was the old school way of setting ignition timing. Dec 8, 2013 · I have a 2013 EB and have just recently installed a Roush mechanical boost gauge with vent pod. Vacuum is not a function of the engine size or type. Joined Mar 12, 2011 · 1,891 Posts #21 · Jul 21, 2023. Once cam timing is confirmed and ignition is optimised try setting mixture leaner. Oct 17, 2022 · The problem: 1) My car seems to have a turbo flutter sound when letting go of boost, this is new and shouldn't be happening as I used to get a woosh. If vacuum decreases at higher rpm, an excessive amount of back pressure is probably present due to a restriction in the exhaust system. A quick way to check for that is to TEMPORARILY disconnect the vacuum advance and see if the problem persists. The test results indicate: A. 5 unit flutter. If I rev up the engine the needle is steady but at idle it's not pretty. The gauge sits at 1lb even with the bike off, so I turned the boost down, so that it would peak at 9 on the gauge. Rev it up high enough and the needle will barely move. At idle, the gauge nee-dle will flutter rapidly over a wide area, but the reading steadies when you rev the engine. sounds like miss-adjusted carb idlemix. Adjust timing and fuel to get it idling well at the desired rpm and then use the AFR gauge to confirm that your AFRs are reasonable. If the vacuum is the same or decreases, the exhaust might be restricted. The vacuum advance is the only vacuum connection on the carb and the rubber hose is new. For the past couple months or so, my car rpm will "flutter" at idle, but runs totally fine while driving. however the idle of the auto trans will be about 100 rpms fasted to overcome the drag of the torque converter with the car in drive, the purpose of that of course is to keep the Apr 7, 2018 · Vacuum gauge, AFR gauge and just general sound and feel. SO, I am wondering if a vibrating vacuum gauge is normal for these y blocks, or if I need to begin thinking about a valve job. Then you hope the advance curve works for your engine. Note the size of the vacuum gauge used here. With the vacuum advance connected, it looks like I have about 25-30 degrees of total vacuum at idle. Then return to idle and set idle screw back at 800RPM. If the vacuum level flutters back and forth at idle and gets worse at a higher RPM, start looking for a broken rocker arm, a bent pushrod or a broken valve spring. I had 11 inches vac dead steady at 1200 rpm. When at idle the fuel pressure gauge seems to be fluttering plus and minus about 2 Lbs. Intermittent drops in vacuum at idle and under cruise could indicate a sticking valve, and needle drop of vibration under acceleration can indicate a bad valve or valveseat. The amount of vibration at idle is about ½ in of vacuum & maybe a bit more. This seems odd to me, but I haven't had any boosted car since my 94 mustang 351 Vortech. Did both and still no change. adjusting a carb with an auto or manual transmission does not differ in the trimming procedures of the mixture screws . Is the fluttering because of the odd fire engine? I tried it on my v6 cj5 with the same results. The vacuum gauge is hooked to the same tree on the intake, in the same position. The symptoms are misfires at idle (tune is known to do that) and while cruising the vacuum gauge will flutter, around the 20ingh reading. So issues are Low vacuum, miss fires at idle, will not start the first, second, possibly the 5th time. Starts and stops fine but I notice with the vacuum gauge, unless I am idling at like 1200 rpm the needle is bouncing all over the place. Apr 1, 2012 · 1987 - 1996 F150 & Larger F-Series Trucks - 460 vacuum at idle. Learn how to adjust idle mixtures, monitor vacuum levels, and diagnose problems effectively. Feb 19, 2014 · Technical Forums and Vehicle Assistance. com Vacuum Gage Connection. 75 to about 15. Today I added in a vacuum canister and rerouted a few vacuum lines per what a few threads on here said. Now, I'm not sure if I have a faulty gauge or if it was truly set at the correct boost level anyway due to inacurracy of the gauge. 7 or so CR. Sep 27, 2016 · I run premium fuel and have only recently began adding lead substitute into the fuel and zink into the motor. Usually, vacuum at 2500 will be greater than idle vacuum. Last autumn I let a mechanic adjusted the valve lash, some where off a bit but before and after the adjustments still the same readings. With a pv that's 2" lower than idle vacuum it would open every time you bump the throttle causing a rich May 8, 2011 · None of my gauges go past 30 Hg. Sadly, I forget what exactly it means, but I do know the engine seems to miss at idle. 0, you only need a boost gauge. Aug 22, 2004 · Originally Posted By: sasilverbullet 70 460 Lincoln engine: At idle a vacuum gauge connected directly to manifold vacuum is jumping between 15-17. SUBTRACT 4. Connect the gauge to a "manifold" vacuum source, NOT "ported" vacuum, that rises as RPM increases. Feb 13, 2013 · If the vacuum level is fluttering back and forth at idle but flutters in a narrower range at a higher RPM, you likely have a leak in a manifold gasket. not a lot of May 27, 2017 · I was setting up my new carburetor on my marine 383 and hooked up my Mity Vac pump to check vacuum while adjusting my idle mixture. You also might want to tap into the intake elbow for the boost reading. bqiernn zdsphr dypcrr gqkfyd lccd ksmd cwgry zlhen xmahfa dhwb