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 ...
15
votes
3answers
557 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 ...
15
votes
4answers
1k views

What does it mean to retard an engine?

I have come across this term. What does it mean to retard an engine? When would you typically have to do such a thing? What can happen if you don't or incorrectly retard the engine? What sort of ...
15
votes
3answers
1k views

Why are there multiple CAN buses in vehicles?

There are a number of questions on the CAN bus but none (so far as I can tell) that explain why there are several CAN buses in a vehicle. From what I understand many different nodes can be connected ...
15
votes
4answers
5k views

Is downshifting on hills harmful for non-trucks? [duplicate]

Possible Duplicate: Does Downshifting (Engine Braking) Cause Extra Wear and Tear? Since the days of taking drivers ed (many years back). I was told that when you encounter a steep or extended ...
15
votes
3answers
13k views

When car is standing still, I smell Diesel exhaust. Why?

In my 2003 Opel Vectra, the cabin air smells of Diesel exhaust while stopped at e.g. a red light. The exhaust smell goes away when driving, and it also doesn't come back if I turn the ventilation off ...
15
votes
4answers
67k views

Symptoms of Lean or Rich carb settings on a motorcycle

I have a 1981 Yamaha XS650. I recently put in K&N stock replacement filter (ie, they are in the airbox and conform to the size of the original), however they may be leading to a leaner mixture ...
15
votes
2answers
861 views

Why did Ducati decide to use the desmodromic valve train rather than a more tradition valve train?

Ducati's use a unique method to open and close their valves. It's called the desmodromic valve train. The desmodromic valve system does not use springs to close the valve, it uses the cam and has a ...
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
6answers
6k views

2000 Jetta runs rough, shudders on cold start only on wet days.

This is an issue I've had off and on for, embarrassingly, at least a year: On misty or wet mornings, everything starts out fine but, a few minutes into the drive (like clockwork. I even know the ...
15
votes
3answers
34k views

What exactly is a “burnt valve” and what causes it?

I've come across this term a couple of times in the context of diagnosing engine-related issues, but don't know what it refers to. Here is an example from an automotive forum I frequent: I gotta ...
15
votes
1answer
3k views

What is happening when a two-stroke engine is said to be “four-stroking”?

Many years ago, I was involved in a hobby of building and flying model aircraft. The aircraft used alcohol-fueled 2-stroke engines with glow plug ignitions. When these engines ran rich (and always at ...
15
votes
1answer
6k 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
1answer
836 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
1answer
125 views

Dynamometer Question - How is it operated and what are they doing?

When guys are doing dyno runs they to do it in a gear, interact with the keyboard and then do it again in another gear. It seems they do multiple runs in multiple gears. In this post Paulster ...
15
votes
1answer
2k views

How do I find the correct pins in a CAN-BUS connector?

This question might be too technical for this forum, but I'll give it a go. I have a 2012 BMW R1200R motorcycle with CAN-BUS. I'd like to make an Arduino interface to the connector on the bike, but I ...
15
votes
2answers
10k views

Is Anti-Seize a lubricant, abrasive, or both?

I'll flesh my personal bias at the outset - being a heavy diesel mechanic for a time, and mechanically inclined my entire life, I use Anti-Seize wherever I can. If it has threads and it's not part of ...
15
votes
2answers
316 views

Engine noise / rattle when clutch is fully pressed [BMW 320d e46, manual]

I have a strange noise, like a rattling/stomping sound at idle, when pressing the clutch pedal. The clutch and the flywheel (DMF), were both changed with new parts. Except for that sound, the car ...
14
votes
6answers
622 views

How to keep wheel ramps from sliding?

I have a very smooth garage floor. When I try to use my wheel ramps for the quick and easy way to raise a vehicle, they will often slide, sometimes just one, but other times both. They will sometimes ...
14
votes
6answers
3k views

Turbo equivalent on electric motors

Is there anything functionally equivalent to a turbo for electric motors? Obviously, I am not asking for something that reuses escape gases to force the entry of air, because there are no escape ...
14
votes
11answers
5k views

Why does stopping and starting a car in heavy traffic burn more fuel?

Why does stopping and starting a car in heavy traffic burn more fuel than simply coasting on a highway at 55 mph?
14
votes
5answers
72k views

What does the 'cc' mean on a motorcycle?

I'm relatively new to motorcycles, my flat mate taught me how to drive his two Royal Enfields around New Delhi, and for the past year and a half I've been taking care of them as they break down ;) ...
14
votes
8answers
60k views

What can cause a car to consume more fuel?

All over my long driver career, I had 4 cars (5 years). I always compare my fuel consumption with other people who have the same car. 3 times out of 4, I found out that my cars were consuming more ...
14
votes
5answers
3k views

What to look out for when buying a car that hit a deer?

I'm looking at buying a car that is only 2 years old, has good miles, a price about a third lower than I would expect...but it had an accident listed on the CarFax. The previous owner hit a deer and ...
14
votes
4answers
8k views

Car crash: when does a car catch fire?

Which kind of crash does it need for a car to catch fire? I'm asking because I was discussing about an accident where a car crashed into a full-grown brown bear. Is it realistic under normal ...
14
votes
3answers
474 views

How does the car's ECU detect a misfire?

I was wondering what the specific mechanism used by car ECU's to detect misfires is, or are if there is more than one method.
14
votes
4answers
2k views

Why do 5- and 6-speed transmissions typically need different gear ratios?

My 2013 Subauru WRX has a 5-speed manual, and I long for it to have a 6th gear when cruising on the highway. A friend has a 2012 Subaru STI with a 6-speed manual, and I noticed his car runs through ...
14
votes
3answers
36k views

How is “outside temperature” measured in a car?

Most cars have a display for outside temperature, and I have been wondering how it was measured... In other words, where exactly is the sensor and how reliable is it?
14
votes
6answers
14k 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 ...
14
votes
3answers
700 views

What does a liter class engine mean?

I have had this question for a long time, can I assume that a 1000 CC engine is able to hold a liter (1L) of water content? Please let me know if my understanding is correct, so I can understand more....
14
votes
2answers
897 views

Why is a W-16 called, well, W?

The term "W-16" seems to imply some sort of configuration that resembles the letter W, which implies three banks of cylinders with one sharing a common cylinder head. In fact, the Bugatti W-16 in the ...
14
votes
6answers
25k views

How to properly dispose of old fuel?

I have some old 2 stroke mixed gas I need to get rid of. This could also apply to old fuel removed from a sitting car or any vehicle for that matter. What is the proper way to dispose of this? Are ...
14
votes
4answers
943 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 ...
14
votes
5answers
1k views

How exactly does running fuel-lean increase the temperature of ignition?

I learned in this question that running an engine fuel-lean will increase the temperature of ignition, among other things such as causing problems with the catalytic converter. I have no idea how or ...
14
votes
2answers
2k views

Is there a difference between a sunroof and a moonroof?

The sunroof tag here states: The opening in the roof of a car. Usually a glass panel that opens by sliding down and back. However, the owner's manual of my 2006 Mazda 6 refers to the opening ...
14
votes
2answers
426 views

What is a leak down tester and what can I do with it?

Background There are quite a few head gasket related questions on the site. Coolant or water in the oil, oil in the coolant or water in a radiator, etc. I'm thinking that some instruction on howto ...
14
votes
5answers
420 views

How do I remove a broken drill bit from metal?

I was building a mount for my custom bobber. My 1/4" carbide drill bit broke off into 3/4" plate of steel. How do I remove it?
14
votes
2answers
106 views

What is an A/R ratio?

I heard the term A/R ratio today while watching a video about turbochargers. What does the term A/R ratio mean? Does it just apply to turbos? If not, what else does it apply to? How is it computed? ...
14
votes
8answers
251k views

Steering wheel shakes at high speeds

the steering wheel sometimes shakes at high speeds around 70 miles per hour. It does not always happen. Some day when I am driving at 70, I feel no shakes. some day it shakes badly at the same speed. ...
14
votes
1answer
1k views

What is a governor and what is it used for?

I was watching a classic car restoration program on YouTube in which they were working on a '50s Cadillac with an automatic transmission. The mechanic in the video diagnosed a transmission glitch as ...
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 ...
14
votes
4answers
88k views

How important is a fuel cap?

I lost my fuel cap a couple months ago and haven't bothered finding a replacement. I haven't noticed any issues with it, but I'm wondering whether it's causing any damage or reducing gas mileage or ...
14
votes
2answers
156 views

Possible causes for poor traction and handling

I have a 2001 Honda Prelude SH with about 180,000 miles on it. For the past 12-18 months, I've noticed consistent strange behavior: Very prone to skidding when braking on uneven roads. Much earlier ...
14
votes
1answer
3k views

Why does diesel engine need a warm-up before the start-up?

When starting up, diesel engine needs approximately 5s before turning the key for ignition. Why is this neccessary and what can be damaged if you don't do that?
14
votes
3answers
95k views

What iPhone/iPad app works best with ELM327 Bluetooth OBD-II reader?

I've found a number of apps for the iPhone/iPad that connect to ODB-II readers via WiFi, but unfortunately that means that it disables 3G and all the benefits of having a 3G device built into my dash. ...
14
votes
5answers
75k views

Is it possible to harm your car by giving someone a boost?

This post explains why it's a potential hazard to clip to the negative post on the dead battery when giving a boost. But I've also been told that I could damage the electronics in my own car if I give ...
14
votes
2answers
379 views

'00 Honda CBR929RR - Unknown issue, help!

Sorry for the ambiguity here.. I'm not sure what the issue is with my bike. I have a bunch of symptoms and my hypothesis is that it's a cascading failure and I'm just seeing a bunch of effects down ...
14
votes
2answers
782 views

How To Get Organized Without a Garage Workspace?

People I've seen who have garages have it made. They have a clean, dry workspace with all of their tools within arms reach. In the most organized garages, a mixture of rolling Snap-on Roll Cab with ...
14
votes
2answers
4k views

How to test a clutch

I have just bought a second hand car, and I have the feeling that the clutch is worn out. How can I do a quick clutch sanity check?
14
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, ...

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