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1500 questions
29
votes
7 answers
We have fuel injection, why not air injection?
I'm finishing studying EFI systems, which set me thinking about induction more generally.
We inject fuel from a high-pressure common rail for many good reasons. We're capable of making stratified burn within a cylinder, provided we have full control…
Daniel
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29
votes
7 answers
When is a cold air intake system beneficial?
Cold air intake must be one of the popular mods there is, and one subject to the most controversy as well. Manufacturers of such systems advertise 5-20 HP gains, yet there are claims that this mod does nothing and may even hurt performance (even…
I have no idea what I'm doing
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29
votes
9 answers
Will higher octane fuel improve gas mileage?
I've heard from some people that high octane fuel will increase gas mileage. Around here, we have the basic unleaded(87), mid-grade(89), and premium(93 or 91). I've been using the basic 87 unleaded forever because it was the cheapest. Also, in my…
Earlz
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28
votes
2 answers
How to deal with rust
I accidentally drove my car over a curb a while back. As you probably already know, the car suffered from minor scratches and dents on the bottom side, near the rear tyre. Now, I've noticed that it's now slowly developing rust on the scratched…
happy_soil
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28
votes
10 answers
Top off gas with old oil, is that bad?
When I change my oil I don't like going all the way back to the station to drop off the old oil and I don't want to pour it in the river, so I put 17 gals of premium in my 18 gal tank and then top off with my old oil. It's a regular gas car, not…
Rob
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28
votes
2 answers
Do I have an oil leak if I have to add oil?
I don't change the oil all that often (maybe every 8000 miles) and on my 10 year old car the oil light comes on and I need to add a quart or two (and then I start thinking I practically changed the oil and don't need to worry for another few…
tooshel
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28
votes
4 answers
How do I test my car battery?
My car still starts fine but when I turn off the car (just the motor . . the key is still in and "on") I noticed the headlights dim to almost off. It's and older car and the headlights don't turn off automatically.
The battery is over 4 years old…
tooshel
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28
votes
6 answers
Do cars consume less fuel when in Neutral?
Imagine we're going down a hill and we're driving a manual car. There are two situations:
If I put my car in neutral it will go downhill without any need for the injector to squirt fuel into the system, just enough fuel for the engine to idle.
I…
Andrew Ravus
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28
votes
4 answers
What causes an engine to burn oil?
What are the different problems that can cause an engine to burn oil and in general how difficult / expensive is each one to repair? How do you diagnose each potential cause?
I found this article which describes some of the problems:
Why Does My…
Robert S. Barnes
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27
votes
9 answers
What's the point of the D3 gear in an automatic transmission?
My Honda Civic has a D gear and a D3, which apparently prevents it from going into 4th. Why would I want to do this? What is it good for? Does it make my fuel efficiency better or worse? Does it make the transmission's job easier or wear it out…
endolith
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27
votes
10 answers
Rats biting off fuel line ( again and again and again )!
For about the last year, a rat (or more) has been biting through the fuel line of my car and last month was the 4th time now. We have two cars in the garage at our place, but the rat is bothered about just this one car in particular. I have replaced…
vick_4444
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27
votes
5 answers
Why should the fuel petcock valve be turned to “Off” position when not using the vehicle?
It’s mentioned in the user manual of my motorbike, that when not using the vehicle, I should turn the petrol tap (the one that has three positions “On”, “Off” and “Reserve”) to “Off” position. I don’t understand why that’s necessary (and I need to…
Nav
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27
votes
10 answers
Manual transmission at stop: 1st with clutch in, or neutral with clutch out? -OR- Throwout Bearing wear
When sitting in traffic or at a long red light, is the Best Practice to have the car in 1st gear with your foot on the clutch, or in neutral with your foot off the clutch?
Some say that you should be in gear to be ready to move if necessary.
Some…
mac
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27
votes
7 answers
"Fill nitrogen in tires" poster - are the claims credible or just hot air?
I saw this poster at a tire shop earlier today
As the image quality isn't great, I'll reproduce the advert's claims in writing:
Take the lead! Ride smart!
[Nitrogen] for your SAFETY & ECONOMY
Nitrogen molecules are bigger than normal air
Less…
Zaid
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27
votes
10 answers
How should I remove a paint scuff on my vehicle?
The painted edge of a side mirror on another car recently scraped the side of my vehicle, leaving a scuff of paint about half a meter long.
There is no indentation or scratch, but the other vehicle left its mark behind in a very difficult-to-remove…
JYelton
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