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Vacuum Gauge Though little understood, the vacuum gauge is probably the best single indicator of your engine's health you can get. A Little Background When your car is idling-whether it's fuel injected or carbureted-the throttle plate or plates are restricting the amount of air the engine can breathe in. The pistons are attempting to "suck" the mixture past the throttle. (Of course, in reality, it is atmospheric pressure that is attempting to "push" air into the engine as the pistons travel downward on their intake strokes.) When throttle is closed, vacuum is high in the intake manifold, from the throttle plate(s) to the combustion chambers. By contrast, at wide open throttle there is relatively little restriction to outside air entering the intake manifold, so vacuum in the manifold is very low. A vacuum gauge reads pressure differences from atmospheric pressure, so the reading is zero in our "normal" sea of air. By convention, vacuum gauges in the US read "inches of Mercury." Reading the Gauge Unlike a fuel gauge, the vacuum gauge will keep you entertained with its instantaneous, wide-ranging movements. When you floor the accelerator pedal, you can watch manifold pressure (another word for vacuum) swing from strongly negative to nearly zero (atmospheric pressure). When your engine is "on the overrun," like using engine braking down a steep hill at high RPM, you'll see really high vacuum readings. Naturally, turbocharged and supercharged will show very different results, with readings swinging into the positive at high speed. IAP's vacuum gauge is not designed for turbo or supercharged vehicles. Your vacuum gauge is also a sort of "poor man's" fuel mileage indicator; when vacuum is low, you are burning more fuel. Absolute readings are not as useful as changes over time. That is, if you establish baseline readings under a variety of circumstances, you will know what to look for if your engine begins to deviate. Everything else aside, a high vacuum reading tends to indicate a healthy engine. Having said this, we can make generalities about the readings you can expect. Note that engines with performance camshafts tend to read lower vacuum. Readings are also lower at higher altitudes; the rule of thumb is approximately 1 inch of mercury for every 1,000 feet of altitude gain. The following readings will not apply to turbocharged engines, or cars with a separate venturi for each cylinder (like Weber DCOE or Dellorto carbs). All readings are inches of mercury (in. Hg.). ENGINE STATE VACUUM GAUGE READING INDICATION Steady idle (800-1200rpm) Gauge steady, 17-22 Normal & healthy Steady idle (800-1200 rpm) Intermittently drops several needle divisions Sticking valve or broken valve spring Steady idle (800-1200 rpm) Steady, low reading, 8-14 Small vacuum leak or valve timing off; could have low compression/worn rings (verify with a compression or leakdown test). Steady idle (800-1200 rpm) Steady, low reading, under 8 Vacuum leak (check brake booster, vacuum lines, etc.) Idle (800-1200 rpm) Needle drops sharply on a regular rhythm Burnt valve, or a valve with clearance too tight Idle (800-1200 rpm) Needle drifts up & down, along with rpm drift Mixture off or small vacuum leak Idle (800-1200rpm) Vacuum gradually drops Excessive exhaust back pressure (plugged muffler or catalytic converter) Idle (800-1200rpm) Intermittent fluctuation Ignition miss; sticking valve Idle (800-1200rpm) Steady, above 22 Ignition timing may be too advanced Open & close throttle quickly Drops to about 2, jumps to about 25 Healthy engine Open & close throttle quickly Drops to 0, jumps to about 20 May confirm worn rings (especially if idle shows only about 15-20) Verify with a compression or leakdown test. More over here: http://www.earlycuda.org/tech/vacuum2.htm http://www.centuryperformance.com/vacuum.asp http://www.international-auto.com/vacgauge.html

Hi guys .... would like to know what is the best time to wax a brand new car ????? I have drove my new car for 3 weeks liao ... dunno when should i wax the car ???? Can give me some tips in waxing new cars ??? Any dos and don'ts ?????? heee ... me just got my corolla and dun seem to know anything bout car maintenance .... so gotta seek help .... thanks.... gam sia

Dear All, Please recommend which Leather Cream/Conditioner is good and long-lasting?? My current one last only about 4 days, after that the smoothness disappeared... Thanks !!

Hello bros, can anyone tell me the diff of DOT 3,4, 5.1??? Guess 5.1 is the best right?? What about brands, which is best?? (I abit kiasu lah) Thks many many......

Guys ... need some help here. This morning I got a flat tyre, wondering near redhill or alexandra have any good tyre shop to recommend? Thanks ...

Asking for a friend. any lobang here?

Guys, Any comments / experience on the best 2 litre engine (NA, Turbo, supercharged)? TL

and cheapest too. Any recommendations? Cheers

What is the best recommended shocks for this model and the price ?

This should make our Jazziegirl happy... Tokyo, January 9, 2003 --- Honda Motor Co., Ltd., today announced that its small car model, the Fit, achieved cumulative unit sales of 250,790 units in Japan in 2002, according to statistics from the Japan Automobile Dealers' Association. Thus, Fit became the top-selling vehicle in Japan, the first time that a Honda model has reached the No.1 spot in yearly cumulative sales. Since its launch in June 2001, the Fit has proved popular with a wide-range of customers for its trend-setting styling, good fuel economy and excellent user- friendly features. Its cumulative sales now total 355,088 units in about a year and a half since its launch. The Fit was first exported to Europe in November 2001, and is currently sold to high acclaim in about 60 countries worldwide, as of the end of December 2002. Including exports, cumulative production of the Fit, which is manufactured at the Suzuka Factory, has exceeded 400,000 units.

yoh brothers... any thoughts on the best brake pads, disc and drums for our E36s??? Pagid = Good but dusty PBR MetalMasters = Excellent and minimum dust but wears out discs faster Energid = PML stock

I.C.E Sifu ... What is the BEST match for DVD I.C.E ? Anyone can introduce me 1 Below is the I.C.E that I plan to setup. 1. Able to play DVD / MP3 / Mpeg / VCD. 2. 4" Monitor or 5.6" Monitor with or without touch screen function. 3. 15" x 2 Subwoofer in Box. 4. Component set for rear & front. How many AMP needed ? Need to have any crossover ? Please advise me with this configuration what should I put in ?

We spend more time looking at our dashboard than the exterior of our cars. Which are the three most attractive looking dashboards in your opinion???....... any contributions of pics will be most welcome and appreciated...... Cheers

Any recommendations for a spray-type wheel cleaner for alloy rims? I'm generally pretty lazy when it comes to cleaning my wheels and am looking for a good spray-on and hose-off type... So far I've tried Meguair's spray and TurtleWax foam, but these don't seem to work well.... Grateful for any suggestions...

Account from a RWD Brick owner: Pads are temperature specific. There is no miracle compound yet that I know of that will be exceptional at the initial bite and still not fade after ten stops from 100 mph. You get a range. Be realistic when plugging your driving style into the ranges. Do you really do occasional track outings or would you just like to? If you do, compromise a bit towards a higher temp pad. I have never seen a Volvo specific comparison test. I did see a VW comparison test, and I called the shop that did it. Ferrodo came out on top. The guy I spoke to said he had a Volvo 740T and tried the Ferrodo, but found them no better than stock. He said compounds are varied from car to car/application. What worked for the 2500 lb VW with 10 inch rotors did not work so well for the 3000 lb Volvo with 11 inch rotors. I have used Repco/PBR/Axxis Deluxe and Metal Master on both 240 and 740. I prefer the feel of the Deluxe in daily driving. I have used KVR Carbon/fiber on both 240 and 740. They feel slightly better than the Metal Master. I have never experienced fade with any of these pads, in the daily driving that I do. I admit that I have never found myself in a situation where I have had to brake from 100 to 60 six times within two minutes. I just don't drive like that. I have done it with all these pads once on many occasions, without experiencing any fade. I will probably continue to experiment with pads. I have used stock and KVR cross drilled Brembo rotors. I did not notice any difference. I continue to use the KVR rotors. I have not warped or cracked any in years of use on both a 240 and my 740. But I have never raced. I also use braided steel brake hoses. I have noticed no difference using them. My stock hoses were in good shape and were not balooning much. I will continue to use the braided steel hoses, though. I have used Castrol, Ford, and ATE Super Blue fluid. I have noticed no difference. I'll probably stick with the ATE Super Blue. It is relatively inexpensive for its improved wet AND dry boiling points. I have also changed master cylinders and noticed no difference. Stock to new stock. The only part I have not changed is the power booster (I have replaced check valves). I think some boosters are stronger than others and give that rock hard pedal feel. I prefer to not have as much power assistance so I get a better feel for the brakes, but I do like that instant response from the responsive boosters. For your V8, you might want to experiment a bit. The extra weight in the front could benefit from a slightly more performance oriented pad. Some people have fiddled with brake bias. Apparently wagons had different pressure settings in the rear than sedans, but I am not sure about this. The people who have fiddled have reported good results, but I put this mod in the advanced class as fiddling with bias can be dangerous unless you know what you are doing. You can end up spinning out if the rears lock up too much before the fronts. As for rotors, I have warped both 240 and 740 stock rotors, but they did have a lot of wear to begin with. Good quality is important, but the Brembos are now being made in Brazil and maybe other places and might not be as consistent as they used to be. Still, when I ordered my KVRs about 4 or 5 years ago, I specified Brembos. I have probably close to 100k miles on the rears and 75k miles on the fronts. The rear pads are original KVR; the fronts would have lasted but for the caliper failure.