2
votes
2answers
1k views

Mazda 323: Plugged in Coolant Temp Sensor - Now Car won't Start

I recently bought a Manual 97 Mazda Lantis 323 1.8L DOHC 16 Valve BP. I found the following wire unplugged on the drivers side of the engine, next to the water intake from the radiator: It plugs ...
2
votes
4answers
1k views

how much water can be safely added to a battery?

My 2008 Jetta SE 2.5L has the battery as follows: ENERTEC EMC // 1J0 915 105 AD // 12V 61 Ah 330A DIN // 540A EN/SAE. It would appear that the battery can no longer hold the starting charge after an ...
64
votes
9answers
43k views

Does the amount of fuel in the tank matter?

As long as there is some fuel in the tank, does the fuel level matter? In other words, is it advisable to make sure the tank is mostly full most of the time, or is this just silly? In other words, are ...
40
votes
6answers
9k views

Why do heavy vehicles almost always use diesel engines?

I have always wondered why heavy vehicles such as large trucks and buses almost always use diesel engines, whereas in light cars there is a choice between diesel and gasoline engines. Engine ...
32
votes
9answers
47k views

Is it necessary to 'burn in' or 'break in' a new car?

I've just bought a new 2011 plate car. I've heard stories of people 'burning in' engines for the first few hundred or couple thousand miles using methods such as: Not driving above 50 mph. Varying ...
13
votes
1answer
4k views

how to optimize fuel consumption by changing the rear differential ratio?

Is it possible to improve the fuel consumption (decrease it) in my van by changing the rear differential ratio? I would like to optimize it for low-speed driving about 40 km/h (25 mph). Is it true ...
12
votes
3answers
10k views

How to begin learning engine tuning?

Quite simply, I want to begin tuning and modifying automotive engines for hobby. I have always been fascinated with cars, and I want to become knowledgeable in as many aspects of car tuning as ...
12
votes
2answers
177 views

Motorcycle Four Body Carburetor Synchronization Balancing

I would like to adjust four-body carbs by myself, in order to avoid spent money every time. What are the basic rules, tools and secrets of synchronizing multiple carburetor bodies?
16
votes
8answers
62k views

What causes brakes to pulsate right after rotor and pad replacement?

I have a 2002 Infiniti Q45. I replaced the front rotors and pads on Sunday. It was the first time I've done this on a car, though I have done it countless times on various motorcycles. I was careful ...
15
votes
2answers
6k views

How is engine load determined?

I'm struggling to find information on how engine load is defined. Is it really just a fancy word for torque demand? There are three parts to this question: Is there a theoretical equation that is ...
15
votes
7answers
49k views

Does a strut tower bar have any useful effect on chassis stiffness for a car with 100K miles?

Aftermarket strut tower bars are generally considered to be decorative on many brand new cars. However, it seems to be a bit more logical that a chassis with 100K miles would have developed some flex ...
14
votes
2answers
18k views

WHY does an engine stall? (manual transmission)

Before you write off my question as one that's been answered a million times already, I want to clarify. I understand that the engine needs to go a certain rpm and when you try to engage the clutch ...
13
votes
6answers
625 views

What is the difference between torque and horsepower?

A very basic question - what is the difference between torque and horsepower? Its all over Google, but I am really confused and can't get any satisfactory answers. I'll tell you my confusion: Torque ...
24
votes
5answers
6k views

What is the technical reason the engineer decided the motorcycle gear pattern as follows?

The gear pattern is selected by clicking a lever with your left foot, and is typically laid out as follows: 6th gear (if applicable) 5th gear 4th gear 3rd gear 2nd gear NEUTRAL 1st gear What ...
21
votes
6answers
25k views

Is Start & Stop technology good or bad for my car? (Alfa MiTO)

I was recently in the lucky position to obtain an (almost brand new) Alfa Romeo MiTo, Progression. Like many new cars coming out these days, it has "Start & Stop" technology that turns the engine ...
18
votes
2answers
11k views

Why doesn't the engine stall out when you come to a stop with an automatic transmission?

When you come to a stop with a manual transmission you have to push the clutch in or take it out of gear to keep the engine from stalling out. What keeps the engine from stalling in an automatic ...
11
votes
3answers
2k views

Can I use washing up liquid to wash my car?

I was just wondering, can I use something like Fairy washing up liquid or dish soap (which is added to hot water in a sink or basin to wash plates, dishes and cutlery etc)) in warm water to wash my ...
9
votes
4answers
9k views

How to assess battery charge level and alternator performance?

What diagnostics can be done to to assess battery charge level? I'm interested both in one-off tests like can be done in car service and also continuous monitoring during normal use. Car panels ...
8
votes
1answer
100 views

What is the “propane test” and how is it carried out?

This test is often mentioned in the context of figuring out what's wrong with a car engine's operation (misfires, hesitation, poor fuel economy, etc.) What is this test and what does one need to ...
8
votes
3answers
6k views

Brake cleaner vs carb cleaner vs throttle-body cleaner

So I was spring-cleaning my man-cave/garage over the weekend and came across my assortment of chemical sprays - specifically carb cleaner and throttle body cleaner which caught my eye. Is there any ...
7
votes
5answers
171k views

What is the meaning of BHP and torque in bikes or cars?

BHP = Brake horse power. It says that it is brake horse power but it is generally relates with high pick up (your bikes reaches top speed in lesser time). So what does this actually mean?. Torque = ...
7
votes
3answers
3k views

Squeaky Brakes: How much of a concern are they?

I recently bought a 1998 Jeep Grand Cherokee from a dealership. When we bought it, I noticed that the brakes were not working very well, and the dealer fixed them before we finalized, putting in a ...
5
votes
2answers
591 views

Writing CAN Messages

I want to know what should I write with the CAN ID to send it to ECU. I am using ELM327 and Raspberry Pi with all connections to OBD-II. Initially for sending general PIDs to the ECU through ELM327 ...
5
votes
2answers
7k views

Engine braking with an automatic transmission

For reference, I've reviewed these three questions: Manually shifting an automatic transmission? Does Downshifting (Engine Braking) Cause Extra Wear and Tear? Is engine braking harmful? I drive a (...
24
votes
3answers
134k views

What does a water like drop coming out of the exhaust of the car signify?

Sometimes while driving in the traffic, I come across a car or two which would be dripping water-like drop from it's exhaust steadily in a break of 4-5 seconds. I tried to ask a couple of people at ...
18
votes
7answers
117k views

Is idling bad for your engine?

If I sit in my car for 30-40 minutes with the AC and the car idling, does that "hurt" the engine, or does it simply waste gas and pollute the air? Would it be better if I turned off the car? A ...
16
votes
5answers
90k views

Just HOW urgently should I replace this tire? Is it safe to drive on at all?

It's my rear right tire. It has a significant bulge in the sidewall. Here are two pictures of the bulge (original URL): Do I need to replace it before I ever drive on it again? Should I put on ...
13
votes
6answers
14k views

How to improve fuel economy in high-mileage car?

I'm driving an 2003 Acura TL 3.2 with 177K miles on it. I bought the car with 110K miles on it. It seems to me that the car is not getting the same fuel economy that it did when I acquired it. I ...
9
votes
3answers
49k views

Does giving gas while releasing the clutch cause unnecessary wear?

I drive a 2013 Ford Fusion SE with manual transmission. I learned to drive a manual as a kid but picked up a lot of bad habits. In particular I tend to naturally ride the clutch. Now, of course in 1st ...
9
votes
2answers
3k views

How does the change oil light system work and does it matter what type of oil you use for it to work properly?

I want to know if the methods a vehicle decides when to turn on the oil change light have to do with the qualities of the motor oil used in the last oil change. I have heard that the vehicle's ...
7
votes
3answers
8k views

What is involved to recharge the Air Conditioning System?

What is involved to recharge the Air Conditioning System? I believe you need a machine to do it, so I am guessing you can't do it yourself.
6
votes
2answers
233 views

Which knob setting best cooks the mold inside HVAC?

I am trying to eliminate odors inside HVAC by cooking the mold that is presumably causing them, as suggested in http://mechanics.stackexchange.com/a/146/15334 (which got 39 upvotes) However, I don't ...
5
votes
2answers
2k views

Foul Smell when turning on air conditioning

I have a 2007 Chrysler Aspen, and recently (past 2 weeks) when I turn on the ac, I notice a 'foul' smell, like burnt rubber, or even sulphur-like. The smell will last a few minutes and will gradually ...
4
votes
3answers
2k views

Realistically, how much can I expect to improve cloudy headlights by polishing?

The headlight lenses on my vehicle (a 2001 Ford F-150) are cloudy, and presumably as a result, the headlights are not terribly effective. (I could post a photo if you want.) I bought a polishing kit ...
4
votes
4answers
37k views

What is the proper way to extract a broken sparkplug?

When dealing with a car with aluminum head(s), what is the proper way to extract a broken sparkplug?
20
votes
4answers
22k views

What are the benefits of low profile tires?

I have yet to find anyone that knows of any benefits of low-profile tires. All of the pros that I've asked have said there is no benefit. Naturally, the number of pros that I have available to ask is ...
17
votes
4answers
44k views

Why does a Turbocharger only produce boost when the engine is under load

As per the Title. Why does a turbocharged car only produce significant boost whilst the engine is under load. Is is something to do with how much exhaust is being produced or is there some kind of ...
15
votes
1answer
844 views

How important is time-based servicing vs. distance-based servicing?

For years I have been driving a very old car, and servicing it every 10,000 kilometres even though it took me almost a year to drive that much. Now I have a newer car which I care about more. It's ...
15
votes
3answers
563 views

What is valve float and how does it impact engines?

The Wikipedia entry is hard to grok: Valve float is an adverse condition which can occur at high engine speeds when the poppet valves in an internal combustion engine valvetrain do not properly ...
14
votes
4answers
946 views

Strange overheating behaviour

My 10 year old Litchfield Forester STi needs a bit of maintenance to sort a minor oil leak but other than that has been behaving well for the past year with regular oil top ups. This week on the ...
12
votes
1answer
10k views

How does an automatic gearbox know when to change gear

As the title suggests, how does an automatic gearbox know when to change gear, for example, how does the autobox know to shift down when you hit a gradient for example, also how does it know to shift ...
12
votes
12answers
42k views

Couldn't start my Volvo due to Key Error. Called assistance and he fixed it by hitting the key with a screwdriver. What could be the error?

My Volvo S40 (06) would not start when I turned the ignition key. I got a message that was somewhat like "Key Error, please try again". I tried with both my keys so it wasn't the key itself. I think I ...
10
votes
8answers
1k views

Is shifting to neutral on a decline more fuel efficient than keeping the gear engaged?

I always had the habit of shifting to neutral on long declines and using the brakes to slow down as needed. Intuition made me believe I'd be saving fuel as opposed to keeping a gear engaged. However, ...
10
votes
2answers
118 views

Why Have More Than One IAC Type Device On an Engine?

I've had two Mazda's, a 97 323 and 98 626. On both these car's engines there was only a single IAC mounted on top of the throttle body, and no other device for adding air flow on the intake side. ...
9
votes
4answers
517 views

Starting a 2 stroke jet boat after several years

The parents in law gave me a jet boat, it hasn't been started in 5 years. The boat resided in NH on a trailer on their yard for 5 years, so it has seen freezing temperatures frequently. From what I ...
8
votes
1answer
326 views

Battery Light Won't Go Off Since Changing Battery

I just changed the battery on my 98 Mazda 626 and now the battery light comes on and stays on after starting the car. I checked the battery and it's reading 12.8v with the engine off, and 13.8 with ...
8
votes
1answer
197 views

What exactly are fuel trims?

What is meant by the term "fuel trim"? Why are they so important in diagnosing engine operation issues? How do short-term fuel trims differ from long-term fuel trims?
7
votes
2answers
21k views

Engine Size and Fuel Consumption

I have this weird misconception that the engine size is related to the amount of fuel being burned in one cycle(4-stroke engine). I know this is stupid but how does engine size relate to the amount of ...
7
votes
1answer
2k views

Why would turning on the A/C affect my alternator output voltage?

So yet another chapter unfolds in the A/C gremlin saga of my LS1 Chevy. Backdrop A/C compressor is relatively new (2 years old) One of the belts is squeaking (not sure which one) Recently performed ...
6
votes
3answers
38k views

Can I reprogram a used Mercedes smart key?

I want a new key for my Mercedes Benz and I've heard that you can get a used smart key for much cheaper than a new one from a licensed Mercedes mechanic. Can I reuse an already programmed Mercedes ...

15 30 50 per page