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Old 06-10-2007, 11:09 PM   #1
prometheum
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Member#: 92003
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Location: Tatooine
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04 bicycle!

Default 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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Old 06-10-2007, 11:16 PM   #2
AkDrewDogg
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2004 WRX
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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
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Old 06-10-2007, 11:22 PM   #3
shortfuseWRX
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ok im gonna ask..... how do you know your car is knocking?


sam
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Old 06-10-2007, 11:24 PM   #4
prometheum
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Quote:
Originally Posted by shortfuseWRX View Post
ok im gonna ask..... how do you know your car is knocking?


sam
the check engine light flashing (utec)
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Old 06-10-2007, 11:29 PM   #5
prometheum
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Quote:
Originally Posted by AkDrewDogg View Post
if u hear a knock the damage is already done sorry man

id borescope it and do a leakdown
used oil analysis doesn't seem to think so

Quote:
Copper and lead (from bearings) were higher than universal averages but that is mostly due to
the new parts wearing-in. Both should improve in future oil changes as the engine matures. Silicon
was low at 5 ppm showing good air filtration while the 0.2% level of insolubles indicates good oil
filtration. We found a bit of fuel, probably from idling or not taking the sample with the oil hot. We don't
get worried about fuel until it goes over 2.0%. We suggest a couple more ~3500-mile oil change
intervals to improve copper and lead wear.
Quote:
Thanks for the note about the new turbo. That likely explains the high wear we found. It's from
new parts breaking-in and should improve with subsequent oil changes. We suggest keeping the oil
runs short until wear improves, as the excess wear metals make the oil abrasive. The oil was in good
shape physically, containing no moisture, fuel, or coolant. Insolubles (oil oxidation due to heat, use
and blow-by) were low at 0.3%, showing good oil filtration. The TBN read 4.0 showing some active
additive left. 1.0 is low. Check back in ~3K miles to monitor wear.
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Old 06-10-2007, 11:40 PM   #6
shortfuseWRX
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Quote:
Originally Posted by prometheum View Post
the check engine light flashing (utec)
ah i c. well the wrx's and sti's i believe have two fuel maps stored in teh ecu from the factory. one is low octane, and the other is high octane. perhaps you were on the high octane map and it would knock?


sam
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Old 06-11-2007, 12:57 AM   #7
Kiwi Fella
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warmer temps normally result in less knock
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Old 06-11-2007, 03:28 AM   #8
soldmyboxster
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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.
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Old 06-11-2007, 03:58 AM   #9
asianhulk
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Quote:
Originally Posted by soldmyboxster View Post
I thought colder temps resulted in less knock, due to the associated reduction in charge temps.
I believe...when temps are up, with the warmer air brings in less air being able to move thus making it more of a rich environment versus a reduction of charge temps which would be colder (cold weather), that leads to more air being moved around making more of a lean environment...knock knock

what is up w/ the utec anyhow, its one knock happy EM :P
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Old 06-11-2007, 05:27 AM   #10
soldmyboxster
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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.
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Old 06-11-2007, 06:53 PM   #11
00Maddog
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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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Old 06-11-2007, 11:48 PM   #12
tribalwrx
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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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Old 06-12-2007, 04:50 AM   #13
prometheum
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Quote:
Originally Posted by 00Maddog View Post
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.
its taken it 8000 miles to figure this out?
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