Spark fluctuation (?) on datalog?
09-02-2008, 11:21 PM
#1
Thread Starter
Join Date: Dec 2007
Location:
Posts: 45
Spark fluctuation (?) on datalog?
I datalogged my car last night and noticed some fluctuation in spark. I did a run from 2400rpms to 6k. Attached is a screenshot of RPM and spark from 4000rpms to 5900.
What i'm wondering is if anyone knows if the "V's" in the spark are normal?
--The first time they appear is from 4300 to 4500
--Second time is from 5100 to 5900.
Any input is appreciated...
What i'm wondering is if anyone knows if the "V's" in the spark are normal?
--The first time they appear is from 4300 to 4500
--Second time is from 5100 to 5900.
Any input is appreciated...
09-03-2008, 05:14 AM
#2
2nd Gear Member
Join Date: Jan 2007
Location: Charlotte, NC
Posts: 157
I believe this is where the ECU is pulling timing for knock. I wouldn't worry, I have the same thing. ( I can post a picture of my datalogs if you want). As long as it's not a major dip (like more than 2-3 degrees) it's normal. It will try to run up to the max spark in the open loop table, but it will back off timing if the knock sensors pick up too much noise. This could also be false readings if you have alot of mods (especially exhaust, headers, or cams) that have changed the expected resonance and vibration of a stock motor.
Do you feel any vibrations (floor, shifter, etc.) ?
Do you feel any vibrations (floor, shifter, etc.) ?
09-03-2008, 12:46 PM
#3
Thread Starter
Join Date: Dec 2007
Location:
Posts: 45
I don't notice any noise, vibration, or spark knock although my exhaust is pretty loud. In one spot where the spark "drops" it goes from 29 to 24.75. Please do post your datalogs, it would be nice to see some others.
Thanks for your reply.
Thanks for your reply.
I believe this is where the ECU is pulling timing for knock. I wouldn't worry, I have the same thing. ( I can post a picture of my datalogs if you want). As long as it's not a major dip (like more than 2-3 degrees) it's normal. It will try to run up to the max spark in the open loop table, but it will back off timing if the knock sensors pick up too much noise. This could also be false readings if you have alot of mods (especially exhaust, headers, or cams) that have changed the expected resonance and vibration of a stock motor.
Do you feel any vibrations (floor, shifter, etc.) ?
Do you feel any vibrations (floor, shifter, etc.) ?
09-03-2008, 03:09 PM
#4
Join Date: May 2008
Location:
Posts: 19
I believe this is where the ECU is pulling timing for knock. I wouldn't worry, I have the same thing. ( I can post a picture of my datalogs if you want). As long as it's not a major dip (like more than 2-3 degrees) it's normal. It will try to run up to the max spark in the open loop table, but it will back off timing if the knock sensors pick up too much noise. This could also be false readings if you have alot of mods (especially exhaust, headers, or cams) that have changed the expected resonance and vibration of a stock motor.
Do you feel any vibrations (floor, shifter, etc.) ?
Do you feel any vibrations (floor, shifter, etc.) ?
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