12
votes
4answers
5k views

Difference between high octane and low octane?

What is the difference between high octane and low octane fuel? I'm not asking if one is better than the other for my vehicle, specifically, but rather what occurs differently both scientifically and ...
11
votes
1answer
241 views

Interference vs non-interference engines

What do people mean when they say that an engine has an interference design? How does it differ from a non-interference engine?
11
votes
3answers
70k views

Check Engine code P0420 Catalyst efficiency below threshold bank 1

After months of normal driving with no problems, my 2003 Honda Civic EX check engine light came on during a long trip. Got it scanned and it's P0420: Catalyst efficiency below threshold bank 1. They ...
10
votes
3answers
31k views

Switching from Reverse to Drive - always stop completely?

I've been told by a couple people that it's really bad for a car to be shifted from Reverse to Drive while the car is still moving backwards. Is this true? In my experience: On automatic cars, this ...
10
votes
1answer
150 views

Coolant Reservoir

Two questions, One, is there any reason why some coolant bottles are shaped in this way? Two, if this coolant bottle was placed on its side such as in the image below for example would coolant ...
8
votes
4answers
10k views

How can I clean the dirt build-up in my alternator?

The alternator in my '04 Lumina SS is its Achilles' heel. It lasts a few years before it starts to overcharge the battery, after which the only practical remedy is to replace it. While I cannot be ...
8
votes
1answer
249 views

What temperature should the A/C blow?

The A/C output temperature on my 2012 Chrysler Town & Country feels diminished, especially in the rear seats' A/C vents. So, I had the refrigerant drained, measured, and topped off (dealership did ...
8
votes
2answers
204 views

BSFC (Brake Specific Fuel Consumption) - How is this a beneficial measurement?

Brake Specific Fuel Consumption or BSFC Measuring various attributes of an ICE (Internal Combustion Engine) and how it performs certainly gives a greater understanding of how a particular ICE ...
8
votes
4answers
30k views

Automatic transmission: Is shifting to neutral while approaching stops bad?

This is not with the intention of saving fuel (as I have seen many answers assuming savings in fuel while doing this). But I have this habit of putting the vehicle into neutral before approaching ...
8
votes
1answer
409 views

Carburettor jetting on installation of aftermarket air filter

I have a 150cc motorcycle and am planning to install an after market air filter(K&N) since the stock one was favoring fuel efficiency and not performance. The bike has a carburetor (Mikuni) not ...
7
votes
1answer
70 views

What is the effect of changing rim diameter while keeping wheel width constant?

Which advantages or disadvantages would I obtain by changing the rim size while keeping the overall diameter of the wheel and the thread width constant? For example, in http://www.tyresizecalculator....
7
votes
3answers
3k views

Cleaning fuel injectors?

I took my car (2006 Honda Civic) to firestone to get an oil change and they told me I should get the fuel injectors cleaned. I was in an Advanced Discount Auto Parts store the other day and I noticed ...
7
votes
3answers
7k views

Why don't FWD cars have rear differentials?

This confuses me. The point of a differential is to make it so the wheels don't slip when one needs to be turning faster than the other, such as during turns. So if the rear wheels are directly ...
7
votes
3answers
753 views

Calculating MPG from MAP sensor (or converting MAP data to MAF data)

My 2002 Honda Accord V6 has a Manifold Absolute Pressure sensor (MAP). I understand that this sensor gives out information in pressure units (psi or equivalent). After doing a bit of research, I ...
7
votes
1answer
3k views

Why doesn't my rev limiter bounce?

I have a BMW 630i Steptronic from 2007. If I floor the pedal in neutral the RPM is of course limited, but it doesn't "bounce" like regular rev limiters. Instead it keeps a constant and "clean" RPM. ...
6
votes
2answers
7k views

What happens to a car engine when giving max throttle while not in gear

I was driving (well standing still actually) during rush hour, and I was suddenly wondering what would happen to a car engine when I would push the accelerator pedal all the way down while the engine ...
6
votes
4answers
26k views

Cheap way to fix peeling clear coat?

The coat on my car is peeling away something like as shown in following picture which I just pulled up from google as an example: This is my first car and I have never done any car work myself ...
6
votes
3answers
30k views

Low beam headlights don't work, High beam headlights do

The vehicle is a 2003 Chevrolet Trailblazer. The low beams aren't working. High beams are. The fuse is perfectly fine (tested and swapped out). The bulbs are fine too. A mechanic told me it could be ...
6
votes
1answer
98 views

I scraped my car against my moms and i need to remove the white scratches

This morning, I scraped my car against my mom's car by accident. I noticed a white scuff above her rear driver tire as well on the front of my Suzuki xl7 with a dent. Can I get it out without taking ...
6
votes
2answers
13k views

Oil pan threads stripped?

EDIT Helpful links on how threads got stripped and by who: http://tl.acurazine.com/forums/showthread.php?t=878261 Seems to be a common problem with some shops, where they don't take good care. ...
6
votes
1answer
509 views

Oily Sludge in the Intake Manifold

When taking off the throttle body to clean my IAC, I noticed that there was a thick layer of oily sludge coating pretty much everything inside the intake manifold: I have two queastions: How did ...
6
votes
6answers
23k views

Uneven rotation sounds when my car gets to 50-60 MPH

My 2005 Mazda 3 with 73K miles (roughly 20K on the tires) on it starts to make a sound, just like your washing machine does when all of the clothes go to one side and its still spinning, when I get to ...
5
votes
1answer
100 views

How can torque converters fail?

In what ways can a torque converter stop working properly? Are there any symptoms that indicate failure, or simple tests one could do to determine a malfunctioning TC?
4
votes
2answers
230 views

Does torque decrease mathematically?

There are 2 cars, car A and car B. Car B is 20% heavier than car A. We all know that this means that these 2 cars will have same power if car B at the same RPM (revolution) has 20% more Nm. Can the ...
3
votes
1answer
222 views

Turbo Charging Suzuki Splash/Ritz

Can I turbo charge my Suzuki Splash/Ritz? Its a 1.2 liter petrol engine with 85HP. What types of engines can be turbo-charged. If it's possible, how would I do it?
2
votes
1answer
103 views

Supercharger calculations

How to determine safe supercharged pressure and CFM for a motor cycle engine (fuel injected 149cc (9.31 cubic inches) 12.9 bhp?
2
votes
0answers
2k views

Fuel Consumption and other Fuel related data from basic OBD-II parameters [duplicate]

I want to know how can i obtain the values of Fuel Consumption, Fuel Economy and other fuel related information from basic OBD-II parameters like Vehicle Speed, RPM, TPS etc. I have noticed that not ...
21
votes
3answers
39k views

Is starting your car with the A/C on bad?

I was always yelled at by my father when I was first starting to drive when I left the A/C on when I turned off the car, and then later turned it back on, with the reasoning that I was ruining / ...
19
votes
11answers
188k views

How do I loosen stuck lug nuts in order to change a tire?

How do I loosen car tire lug nuts (so that I can change a tire) when they are really really stuck? I have tried turning the provided wrench, even standing and jumping on it. This worked for 4 of the ...
18
votes
12answers
53k views

Should I pull my wipers away from the windshield when parked during a winter storm?

When we are expecting snow storm and the vehicle is parked, do we pull out the wipers so they don’t touch the glass to avoid the freezing to the windshield? Or would that hurt the springs in the wiper ...
16
votes
8answers
2k views

Will having a radiator full of engine oil do damage to the motor?

I've got one question; I was looking over this car that I was going to buy and there was engine oil in the radiator. I asked the guys why it was in there and he said he didn't have enough coolant to ...
16
votes
1answer
7k views

Where can I find my car's colour code?

I'm currently shopping around for a touch-up pen to repair some very light scratches on my car. I've found out that our local hardware automotive store can mix the exact colour for any vehicle. ...
15
votes
3answers
1k views

Are there any advantages of idling a vehicle vs. turning it off and back on again?

I was sitting outside, eating my lunch the other day, and a small bus (you know, one of the short ones) pulled up to the sandwich shop I was eating at. I noticed that the driver got out of the bus, ...
15
votes
2answers
12k views

Why would a new gas cap cause the “check engine” light to shut off?

This happened to a friend of mine: The "check engine" light came on in his truck (Toyota). He replaced the gas cap and the light shut off. Then I also had a "check engine" light come on in my 1994 ...
15
votes
6answers
2k views

Why or why not increase engine efficiency by running the car “fuel-lean” (using a turbo or supercharger)?

Everyone wants their cars to use less fuel, right? I read the following passage about running the car fuel lean from this website: Run the engine fuel-lean, that is, use excess air. It is well ...
14
votes
6answers
15k views

How to fix leaky tires after 2 shops couldn't

I have an SUV with factory 16" steel wheels and P235/70R16 tires. The tires have just under 30,000 miles of gentle driving on them. Two of the tires have been leaking quite a bit (about 10 psi per ...
13
votes
4answers
23k views

I drove with my Parking Brake on for 30 mins: should I be worried?

Yesterday, I was driving my car for about 30 minutes on the highway at speeds of up to 60 mph. I felt my brakes weren't really working and looked down to notice my emergency brake had been on the ...
12
votes
6answers
2k views

How to deal with a hot turbocharger

A piece of advice that seems to be widely accepted is that after a long high-speed run, when the turbocharger is thoroughly hot, you should let the engine idle for a while before stopping it. The ...
11
votes
1answer
252 views

How do lambda sensors work?

Virtually every modern passenger vehicle today utilizes lambda sensors from the factory. How critical are they to a vehicle's operation? How do they work?
11
votes
5answers
126k views

Why would there be transmission fluid in the water overflow reservoir?

The car is a '98 Buick Lesabre with the 3800 engine and about 170k miles. It appears as though some oil was in the radiator, but I haven't seen any signs of coolant in the oil. The water pump recently ...
11
votes
2answers
683 views

What's the cause of Diesels' typical clatter noise?

I guess it's related to their basically running off knocking, but if I were to explain it to someone like this, it wouldn't convince me neither. [Edit] From http://www.ford-trucks.com/forums/369700-...
10
votes
6answers
20k views

What is the purpose of plastic engine covers?

I have a 2010 Toyota Corolla. What is the purpose of the large plastic cover that stretches over my valve cover? Does it have a particular function? Are they just for looks? Or are they designed by ...
10
votes
6answers
12k views

Why does a diesel sound like that?

My car is in the shop for a repair, and they gave me a loaner. It's a Chevy Cruze Diesel. Sitting on the driveway, my wife said, "It sounds like a truck". It does. So what exactly it is about ...
10
votes
1answer
429 views

What are Tappets?

I have been looking into a tapping noise after a cold start on my 2003 Opel Agila, and apparently it is caused by "tappets". What are tappets? What is their purpose? Why are the necessary? Will my ...
9
votes
1answer
161 views

What are the various kinds of tappets / lifters and the advantages / disadvantages of each

A previous question about tappets found here: What are Tappets? covers the basics of tappets. If we go the next step, here are my questions: What are the various kinds of tappets / lifters? What ...
9
votes
1answer
117 views

What is Lobe Separation Angle (LSA)?

What is Lobe Separation Angle (LSA) and how is it used in camshaft design? How is it measured? What difference does a long or short LSA make?
9
votes
1answer
371 views

How does intake manifold runner length effect the power curve of a car?

Recently I learned that a number of things such as the cam profile, compression ratio and the intake manifold runner length and volume can all effect the power curve of the engine. Here is an ...
9
votes
5answers
182 views

What can I do with used motor oil?

Besides recycling? I've heard, for example, that I can use it to lubricate the drive chain (in a motorcycle / bicycle), but that doesn't appeal to me.
8
votes
4answers
274 views

How should I remove paint from calipers?

I have a set of STI brake calipers that I'm interested in refinishing. From the factory, they come with a black finish and white lettering. What is the best way to remove the existing finish so that I ...
8
votes
3answers
10k views

Bad to run the car for a short duration, turn it off, and start up again?

Is it bad for the car to start it up in the morning, spend 10 seconds driving it out of the garage, then shut it off while I go close the garage door and then a few seconds later get in and start it ...

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