possible knock - Subaru WRX Forum
 
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post #1 of 7 Old 08-04-2008, 12:29 AM Thread Starter
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possible knock

my car has been jerky in wot in 3rd and 4th gear in the range of around 2.5k to 4k rpms.
my boost seems to be holding like it always has and i have a widband a/f and all that looks safe and normal. I have tested the clutch and it holds like the day i bought the car. i'm been running an custom opensource map for about 5 months now and my car runs fantastic except for this minor issue. could my car be pulling timing because of knock? im not hearing anything its just a tiny bit jerky...? my car is going to my tuner on Tuesday just so he can check it out.
here is my a/f and boost graph. i also changed my plugs and my air filter and it was still jerky
http://i269.photobucket.com/albums/j...fcopyFINAL.jpg
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post #2 of 7 Old 08-04-2008, 12:39 PM
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Why don't you try datalogging the car and posting the log...

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post #3 of 7 Old 08-05-2008, 06:20 PM Thread Starter
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well i just got back from my tuner and we did a few pulls to log my car and it was pulling timing. the most it pulled was -2.5 degress but i did pull -3 on one of the pulls. it was only happening in the low rpms.

as far as knock the log file only should a value of 1 (i THINK that was the kc value...not sure) all the way rpm range so i belive he said it wasnt knocking...idk we talked for a long time and i asked a lot of question as always and i dont remember.
he tweaked the map and added some timing to where the ecu was pulling and that fixed the issue.

i asked what would cause the car to do this and he said a number of things. its been really hot here and my origanil base map was built when it was 50 degrees outside, the fact that im using the hot ambient air to help cool the tmic, small turbo, etc.

the only questions i still have is i know that its never really a good thing that your ecu has to pull timing but is -2.5 to -3 a lot? when timing is pulled is it only because of detonatioin or can other things cause the ecu to retard the timing?
and i know that a tmic is good up to like a 20g would it be helpful if i went with a fmic to help cool the air?
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post #4 of 7 Old 08-05-2008, 06:33 PM
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If you look at the IAM value, if it's not at 16, you've had a knock. Also, depending on the tune it may pull only a degree of timing or even more in the event you get a knock. Just depends on how it's tuned.

Also, intake temps do play a big part on the performance of the car. If you want proof, find a nice cool day with low humidity, make a pull in 3rd. Then wait for an unbearably hot and humid day, make a pull in 3rd. Guess which one is quicker. The colder your intake air, the denser the air and the bigger the bang.

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post #5 of 7 Old 08-05-2008, 07:49 PM
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Originally Posted by 03 CrazyTaxi View Post
If you look at the IAM value, if it's not at 16, you've had a knock.
He has an 06 wrx.It is a 32bit ECU.The max IAM value for a 32bit ECU is 1.

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post #6 of 7 Old 08-05-2008, 08:38 PM Thread Starter
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okay then the iam value was 1 all the way across the board so does that mean my engine was NOT knocking? im just trying to figure out why i was pulling timing.
so if a car pulls like 3 degrees is that light or heavy knock? im just trying to figure out a sort of guideline for timing and whats normal and not so normal
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post #7 of 7 Old 08-06-2008, 01:17 PM
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Originally Posted by kh15 View Post
okay then the iam value was 1 all the way across the board so does that mean my engine was NOT knocking? im just trying to figure out why i was pulling timing.
so if a car pulls like 3 degrees is that light or heavy knock? im just trying to figure out a sort of guideline for timing and whats normal and not so normal
Sometimes road noise/vibration can cause false knock.The sensors are a little sensitive.IAM is sometimes a better indicator of knock then just looking at timing.Plus if you were knocking I have no idea why your tuner would be adding timing.Either you are not understanding what he is saying or he has no idea what he is doing.Like I said,32 bit ECU's (04+ STi,06+ WRX) have a max IAM of 1.Anything under 1 (should show in decimal form like .88 )
is detected knock.You can learn more about it by reading in the RomRaider forum.

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