Questions tagged [pressure]

Physical force applied over an area. Frequently referring to the force that compressed air exerts on the interior of a vehicle's tires and expressed in units such as pounds per square inch (psi) or Newtons per square meter (1 Pascal).

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Low-side and high-side pressures lower than expected after AC repair

I just did my first automotive AC repair, after the compressor in my 2004 Lancer 2.0 ate itself, cracked its casing, and blew all the refrigerant out. I think I did the repair & recharge ...
Cognitive Hazard's user avatar
14 votes
4 answers
5k views

Should I fill my tire?

I measured the PSI on my rear driver tire (using a gauge pin - push it into the needle and a stick pops out with a reading), and I got a reading of 22 PSI. My tires are supposed to be anywhere from 30-...
semore_1267's user avatar
14 votes
5 answers
9k views

Why nitrogen and not carbon dioxide is used in critical tire applications?

In critical applications tires are inflated using pure nitrogen (link). But carbon dioxide (CO2) is a larger molecule (will leak slower from the tire), as well as inert (will not oxidize rim and will ...
Sparkler's user avatar
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14 votes
2 answers
139k views

Checking Tire Pressure when the tire is warm or cold

Witnessed a recent debate about what is the appropriate temperature to check tire pressure at. The debate centered around warm or cold, there wasn't an exact temperature given by any of the parties. ...
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12 votes
7 answers
87k views

Should the inflation pressure for low profile tires be the same as for regular tires?

I always thought that even if you go the large wheel + low profile tire route one should keep the pressure to what's recommended by the manufacturer. However I noticed that some people swear by ...
I have no idea what I'm doing's user avatar
12 votes
2 answers
11k views

How does tire pressure affect susceptility to hydroplane?

Is a tire's propensity to hydroplane proportional or inversely proportional to tire pressure? That is, if a tire is over inflated or under inflated, is it more or less likely to hydroplane?Edit: This ...
BillDOe's user avatar
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11 votes
5 answers
8k views

How critical is it to match the stock fuel pressure regulator pressure when replacing it?

My fuel pressure regulator needs replacing, however the original part from the manufacturer is outrageously expensive. While looking for less financially painful alternatives I've seen much cheaper ...
I have no idea what I'm doing's user avatar
11 votes
1 answer
1k views

Radial tires: Do they bulge at too high pressure?

It's tire pressure time! At least when looking at the recent new questions. So here is another question about air pressure. At driving schools, shops and in the internet you often find this type of ...
sweber's user avatar
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11 votes
1 answer
2k views

Tyre Valve Pin Too Far In

I just bought a second-hand car, and when I got it home I tried to check the tyre pressures, with a simple mechanical pressure gauge like this, which I've used for years on previous cars with no issue....
DaveyDaveDave's user avatar
10 votes
9 answers
3k views

Why is it that when supercharging, it's preferred to compress the input, rather than pull a vacuum on the exhaust?

It's a strange dilemma, but if the power of an engine is determined by the difference in pressure between the combustion chamber and the exhaust, it should follow that turbocharging should be equally ...
tuskiomi's user avatar
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10 votes
3 answers
2k views

Direct Injection Injectors - How do they prevent blow back into the fuel system?

So I imagine a direct injection injector as a fuel injector squirting fuel directly into the combustion chamber. The amount of pressure in the combustion chamber would seem to be enough to push the ...
DucatiKiller's user avatar
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9 votes
1 answer
1k views

Does free revving a diesel engine to 4000 rpm (1.6 crdi- hyundai) cause any damage?

It's a Hyundai CRETA/ ix25 model... clocked 1800kms on the odometer, diesel spec engine 1.6 crdi unit, manual transmission! It has redline at about 4800rpm in the tachometer. When i took it for ...
Vivek S's user avatar
  • 91
8 votes
3 answers
3k views

How To Pump Up Car Tires (finding the optimal PSI for your tires)

I have noticed that all the tires on my VW Passat B5 have "44 PSI" written on them except the spare that has "51 PSI". This seems incredibly high to me so when I filled them up recently at the petrol ...
Max Goodridge's user avatar
8 votes
1 answer
8k views

Why does a tire have the same air pressure when mounted on the car and when not?

The other day I inflated my tires up to 34psi and then when I took one of them off the car. I measured the pressure again to check how much the difference was, and I was surprised that it was still 34 ...
Pablo Matias Gomez's user avatar
7 votes
2 answers
6k views

Does high air pressure throw off wheel balance?

The tire shop balanced my tires at 41 psi, when my recommended psi is 30. I have since lowered it to specification, but would this throw off the balance?
nachos's user avatar
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7 votes
1 answer
2k views

What pressure should i run in my winter rally tyres?

I'm going to buy and run for the first time a winter rally spiked tyre of 145 80 r13, and I was wondering what pressures do people generally use rallying in low winter temperatures on snowy terrain? ...
Flaviu Suciu's user avatar
6 votes
1 answer
911 views

Tire pressure with load and heat

Running a ram 2500 pulling 10,000lbs 5th wheeler...truck door sticker and tire call for 80psi... when pulling the trailer in the summer the heat of the road increases the psi to 90 is that safe or ...
Kph's user avatar
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6 votes
2 answers
2k views

Showing Oil Pressure When Engine Cold and Not Running

I noticed a strange problem on my motorcycle last night. I have a 2006 ZX-10R and as I was leaving work, I noticed the oil pressure warning was not on. Normally, as soon as you turn the key to the on ...
raydowe's user avatar
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6 votes
1 answer
15k views

Difference between fuel pressure and fuel rail pressure

In OBD PID wiki page, there are 2 PIDs listed: Fuel pressure and Fuel rail pressure. Are both of them the same? Can someone please give an elaborate explanation of it - What exactly are they ...
Soumya Sen's user avatar
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6 votes
1 answer
2k views

2010 TDI Jetta Strange A/C Pressure Readings

I recently replaced the compressor and dryer at the suggestion of a nearby shop. I've charged the system and the high side reads a solid 100psi the low side cycles between 70 - 110. Cycle time is ...
user16873's user avatar
5 votes
2 answers
886 views

Tire Pressure Adjustments When Needed

From my understanding there is the recommended tire pressures at the inner part of the drivers door, but I have this question in my head just in case this happens. Say my recommended tire pressure ...
Jomar Sevillejo's user avatar
5 votes
3 answers
7k views

Why is a volume test necessary when diagnosing fuel delivery problems?

I suspect my fuel pump causing intermittent driveability issues. I checked the fuel pressure at the fuel rail and it seems like the pressure is fine: ~2.4 bar at idle, 3.1 bar at engine off (3.09 bar ...
I have no idea what I'm doing's user avatar
5 votes
1 answer
111 views

Tire showing low pressure after few KMs of ride

I am having this question from long back. I am using N2 for my tyres. After a few KM (say some 3-4 KMs), measuring the PSI, shows a less pressure. Whether, due to the increase in the temperature in ...
NANDAKUMAR THANGAVELU's user avatar
5 votes
0 answers
2k views

Diesel fuel pressure issue Fiat Punto 1.3 JTD [closed]

I have a Fiat Punto 188 1.3 JTD Multijet and an issue, that brings me a headache since 2 years. The car is from 2005 and already has 180 000 miles down. Almost every time, the I fast accelerate from ...
Watsche's user avatar
  • 736
4 votes
2 answers
3k views

What could be causing the rapid loss of tyre pressure?

I had a slow puncture a while ago and got the tyre replaced on my Renault Clio because it was bulging and non salvageable. Since then I've been losing pressure in that tyre fairly rapidly. I've had ...
Ilessa's user avatar
  • 143
4 votes
1 answer
2k views

Fuel Rail Pressure dropping & engine shutting down - Whats the cause?

Lately my car had shut down its engine mutiple times while I was driving. Before shutting down it felt like I took of my feet from the gas pedal and then pressed it again althrough I always was on ...
Yannick Huber's user avatar
4 votes
2 answers
2k views

Diesel, fuel pressure drops at speed

Now its my turn.. Volvo 2.0 diesel Siemens VDO When car gets warm, in 4th - 6th gear, the car starts shaking between 1800 - 2200 rpm, no warning lights. Diagnostics show that the fuel pressure drops ...
ArnyPP's user avatar
  • 43
4 votes
1 answer
3k views

Do I follow the same recommended tire pressure when I change to nitrogen filled tires?

I am aware of the recommended tire pressure indicated in the car's user manual and in the driver's door. I've been reading a lot about filling tires with nitrogen and a few of the advantages has ...
Jomar Sevillejo's user avatar
4 votes
0 answers
160 views

Honda Civic 2002 Coolant sprinkles back from Rad cap

I am having issues with this car, so I am reaching out to masses out there who could share some of their wisdom to help me understand the actual issue with this car. It has 262K miles on it. Issue ...
user3400309's user avatar
3 votes
3 answers
8k views

Should I let air out of my tires?

I bought a car brand new 9 months ago. My tire pressure sensor came on. I checked the tire pressure, and it was at 35 PSI. My maximum tire pressure is 51 PSI with a warning not to fill above 40 PSI. I ...
Evorlor's user avatar
  • 285
3 votes
6 answers
1k views

Tyre Pressure Checks for My Car

I know that checking tyre pressure is a very important thing before making long journeys. However, I have no idea how frequently I should check my tyre pressures. For example, If I travel round-trip ...
ha9u63a7's user avatar
  • 335
3 votes
7 answers
121k views

lowest tire pressure for a 44psi tire

I want to know what it the lowest tire pressure you could put on a maximum rate 44psi tire? I have been placing 33- 34 psi on these tires for about half a year now, will it damage my tires? I'm ...
marchemike's user avatar
3 votes
5 answers
36k views

Does tyre pressure affect road noise?

I always pump my tyres up to the maximum (like 45 bar), for maximum fuel economy. However, does this affect road noise?
George's user avatar
  • 6,545
3 votes
1 answer
536 views

Can I still drive my car when one of the tires has lower pressure?

I just noticed this morning that one of my tire pressure dropped a little bit. The others are 34psi, but the front right tire is only 30psi, I checked them only few days ago, they were the same at ...
Ellie's user avatar
  • 31
3 votes
1 answer
355 views

Oil pressure light on Golf R Mark 7

This morning my car stalled when I turned on the engine (left it in gear the night before, stupid me) and my oil pressure light came up for a few seconds then it disappeared. Will it be fine?
Victor Yu's user avatar
3 votes
1 answer
385 views

What can I do to get the oil pump to work?

I replaced the oil pump on a Volvo 240. The oil pump is down in the oil pan underneath the engine. I followed the Haynes manual which said to prime the pump with Vaseline. I put everything back ...
willpb's user avatar
  • 310
3 votes
1 answer
89 views

What type is this compressed air/pneumatic connector?

I need to build an adapter for this connector, however, I wasn't able to identify it. I measured it with a digital caliper. It doesn't seem to be a common connector, at least in Germany. Can you ...
theluckyluke's user avatar
3 votes
3 answers
654 views

Can I add a gasket to my exhaust valve to reduce leak and increase cylinder pressure?

So I have a single cylinder diesel engine. We do not use it to produce power (it is operated by an electric motor) but to measure the pressure at low rpm (100-200). The volumetric compression ratio is ...
Sine Nomine's user avatar
3 votes
1 answer
5k views

Cold weather tire pressure adjustment

I live in a mild-weather area (typical summer temp about 80F/25C, winter 55F/+15C), but occasionally travel to the mountains where temperatures are below freezing (5F/-15C). The cold temperature ...
CarNoob's user avatar
  • 31
3 votes
1 answer
2k views

Tire pressure sensor doesn't read

I work on several makes and models, and found that after replacing brake pads that the "low tire pressure" warning comes on as a sensor fault. Is there something I'm hitting that causes this? How can ...
Alex Volpe's user avatar
2 votes
5 answers
751 views

When does the spark plug ignite the air fuel mixture?

Some people say it's at the end of the compression stroke, some people say beginning of the power stroke.. What do you guys think ?
venomx's user avatar
  • 289
2 votes
1 answer
286 views

Tire Pressure Monitors during very cold temperatures

As outside temperature decreases by 10 degrees Fahrenheit, tire pressure decreases 1 psi. However, in very cold temperatures of -10 degrees Fahrenheit, the vehicle TPMS indicates low pressure but the ...
user avatar
2 votes
1 answer
4k views

Tire pressure with tires on vs off the car

Today, I changed to summer tires on my Toyota RAV4 hybrid. Usually I check the air pressure after changing the tires (well, wheels, actually) with the tires on the car. However, today I instead ...
juhist's user avatar
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2 votes
2 answers
2k views

Hydraulic fluid reservoir caps

Hydraulic fluid needs to be kept clean of foreign debris to avoid damaging/destroying hydraulic fluid lines. It is also known to be hydrophillic; Absorbing water leads to a lower boiling point, which ...
Zshoulders's user avatar
  • 1,646
2 votes
1 answer
4k views

Checking a fuel pressure regulator that is out of the car

I happen to have a fuel pressure regulator of a petrol car lying around left by the previous owner and suspect that it might be still good, since the previous owner was just changing parts randomly ...
I have no idea what I'm doing's user avatar
2 votes
2 answers
549 views

Atkinson Cycle: Does the efficiency of a high-compression engine come from compression ratio, expansion ratio, or both?

I understand that, in an internal combustion engine, efficiency can often (up to a point) be improved by increasing the compression ratio, this being a major reason why diesel engines (which do not ...
DodoDude700's user avatar
2 votes
0 answers
325 views

Is Honda Accord gen 8 A/C Pressure Switch replacement DIY safe?

I have a Honda Accord 2008. I followed the Service Manual and identified that there is no continuity between the terminals of the A/C Pressure Switch. Since the refrigerant was only refilled last year,...
Song Keang's user avatar
2 votes
2 answers
319 views

Low fuel pressure in Volvo S40 1999

My car is Volvo S40 1999 with 2.0 engine. The fuel pressure is on the idle at 2.2-2.3 bars (should be 2.5) and on higher rpm max. 2.6-2.7 bars (should be 3.0). When I unplug the hose that goes from ...
Joni's user avatar
  • 21
2 votes
0 answers
417 views

Can pressure caused by temperature cause ignition coils to unseat?

I've got a Rotax engine that looks like this from the top: The ignition coils look like this when removed: Recently two of the three ignition coils unseated after approximately 10 minutes of ...
alx9r's user avatar
  • 183
2 votes
0 answers
2k views

My upper radiator hose is never pressurized but car never over heats....?

I'm stumped, it doesn't effect the car and no overheating or mechanical issues. Lower one is pressurized but not the top? 06 Impala police package. Do the police versions have bigger radiators and ...
Noah's user avatar
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