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Old 04-15-2009, 11:01 PM   #11 (permalink)
theunchosen
Master EcoModder
 
Join Date: Nov 2008
Location: Cookeville, TN
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Quote:
Originally Posted by hummingbird View Post
Answering a few open questions -
1. Yes Oil changed with the service. As synthetic was 2.5 times as costly as unbranded mineral, I chose mineral.
2. Yes they got the tyre pressure down to 32 (habit slaves!) I insisted and made them take it back to the compressor and filled it back up to 50. Lots of weird glances endured... I check and top up regularly at each weekend using a digital gauge and battery operated pump.
3. AC use was not significant. It was only two / three instances, each not lasting 5 minutes before I got nervous about the FE hit and switched to window cracks.
4. I P&G regularly since Dec 08, (when I got to know about it on joining ecomodder). The change I had with the octane change was switching from granny mode to jackrabbit mode for my acceleration, on reading about the ABA testing done by SVOboy.
5. My car is almost identical to FIT (same platform), has 1.5L 5MT IDSI engine (not the popular Vtec variety), and does not require premium fuel. the premium fuel was touted to make the vehicle run smoother, so was using it.

Unchosen: What is the diagnostic unit you are talking about?

aerohead: Is the knocking thing equivalent to lugging?
Diagnostic units are small calculator sized computers that read the signal the ECU receives from the various sensors in your car and then puts it in a code for you.

Basically its a box that you plug into a receptacle in your car(mine is on the passenger side behind/below the glove box) that tells you what a check engine light means. They usually come with a book that tells you what specific codes mean. Its what the dealer will do everytime you bring a car in because its easy.

Some vehicles have a memory. So it records important events. not like "I turned 12 weeks old today!" but "detonation in cylinder 4" and then also records all the temperature readings(intake, exhaust cylinder rpm all kidns of other stuff too).

It basically alerts you if something is wrong before it needs fixing. Typically I am going to say its not necessary. I have one because there are 3 Del Sols in my nuclear family along with 2 other cars that can use the same diagnostic and codes so its totally worth it for us.

Knock/detonation/ping occurs when the cylinder gets a little too warm or pressure gets a little too high.

The air gets compressed and the spark plug ignites the fuel air. As the spark front travels across the cylinder(from the crown/top) to the piston(bottom) the air at the bottom becomes extremely hot and suffers extremely high pressure. At this point that small pocket of air at the bottom detonates(normal engine cycle just involves the fuel burning not exploding) and causes abnormal pressure and stress against the cylinder walls and piston head/crown/top. Its not really dangerous in non-high performance cars(Ferraris Lamborghinis Honda NSX. . .) as long as its doesn't happen every stroke or every other stroke. If it happens every stroke the spark plugs, valve heads or the walls of the cylinder themselves can cause the fuel to ignite at the bottom of the compression cycle. At that point the engine is toast. Its going to have to compress super-heated high pressure air for 180 degrees of movement(opposed to just a few normally) during which time the heat and pressure are increasing rapidly. In effect you will know when that happens because the car stops immediately. it melts a hole in the piston, maybe the walls, maybe the crown and definitely cooks the valves.

That said your car is smart enough to avoid knocking becoming too intense as long as you don't short-circuit the knock wiring in hopes of higher FE. So don't worry about it unless you are really trying to push the envelope and get lean burn and high compression with the sensors unplugged.

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