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06-10-2007, 11:09 PM | #1 |
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gas quality increasing?
recently i've noticed my car is knocking a lot less; almost not at all in most of the time...anyone else notice it too?
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06-10-2007, 11:16 PM | #2 |
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if u hear a knock the damage is already done sorry man
id borescope it and do a leakdown Last edited by AkDrewDogg; 06-10-2007 at 11:16 PM. Reason: info |
06-10-2007, 11:22 PM | #3 |
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ok im gonna ask..... how do you know your car is knocking?
sam |
06-10-2007, 11:24 PM | #4 |
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06-10-2007, 11:29 PM | #5 | |||
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Quote:
Quote:
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06-10-2007, 11:40 PM | #6 |
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06-11-2007, 12:57 AM | #7 |
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warmer temps normally result in less knock
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06-11-2007, 03:28 AM | #8 |
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I thought colder temps resulted in less knock, due to the associated reduction in charge temps.
I posed the question back in 2003 when I had a turbo on my CRX. Because of the smallish intercooler and high boost levels, I was always on the ragged edge of detonation. What I was concerned about was the increased oxygen content of cold air causing a lean condition, vs. the warmer air causing an overall hotter intake charge (which should have been more likely to cause pinging). What I found was that it was mainly determined by two things: the brand of gas I used and how well the ECU adjusted the fuel trims based on inputs from the intake air temp sensor. Fuel quality was controllable (by doping with toluene if pinging was heard), air intake temp sensor readings were not. I noticed very little fuel trim action from 100 degrees down to 30. It was like intake temp was almost ignored, or at least only adjusted to aiflow values as expected up to zero vacuum. Consequently, I found I was running lean on very cold days (due to greater oxygen content in the fuel), although it wasn't too bad because the cold temps helped supress the problem under moderate boost. The problem also reared its ugly head on very hot days, as the intercooler couldn't keep up and charge temps started creeping up into the 130s F. It's these moderate days where the air is neither very dense, nor is it so hot the intercooler can't do its job that makes for good power. If you can, when it cools off (or you go to Fairbanks), you might want to richen the map slightly in the boost ranges. |
06-11-2007, 03:58 AM | #9 | |
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what is up w/ the utec anyhow, its one knock happy EM :P |
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06-11-2007, 05:27 AM | #10 |
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A good ECU would look at the temperature of the incoming air and increase the amount of fuel for colder air. If you're already pushing the limits on what the engine will tolerate, though, you'll need more fuel when it's hot as well to prevent ping.
For a given air fuel ratio, the colder the charge temps, the less chance of detonation. If you're not going to have a "summer tune" and a "winter tune", then you need to have one tune that applies to all situations, including one with crappy gas. That means not pushing the ignition timing up and dumping a little extra fuel to keep things cool and rich. |
06-11-2007, 06:53 PM | #11 |
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reg. 1st post, your map is getting finer tuned as the ecu adjusts (aka "learns"). especially if you use the same gas station all the time.
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06-11-2007, 11:48 PM | #12 |
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the new utec firmware has the ability to adjust fuel and timing depending on air temp , i think next week i'll finally upgrade from the old 3.1 to the new 5.8 version
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06-12-2007, 04:50 AM | #13 |
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