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Knock, Low Boost, and Low IAM


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I've been running an open source tune from a reliable tuner for a couple years now.


A week ago I was only hitting 7-10 psi instead of my target 20 psi. I figured my BOV was sticking open, but after oiling it, things didn't get better.


I took a LV and saw I only had 0.875 IAM and knock at low load.


Reset the ECU and drove for a couple days and took the LV attached.


Still have low IAM and knock at low load.


Any ideas on what to check out?


I'm guessing either I have some IC piping or exhuast banging around or I have bad gas (in the car that is).




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I think bad gas would show corrected timing in more cells than what you're seeing though it's possible you just aren't hitting those ranges. If you've run it low enough try topping off with known good highest octane possible gas and do an ecu reset.


Any hardware changes since this problem started? Ideally you should reset it again, and do some data logging to try to catch this happening.


Log the following (assuming Romraider):


Engine Load (2byte)

Engine Speed

AF Sensor #1 (2byte) (or WB 02 if avail)

Manifold Relative Pressure (4byte)

Total Timing

Knock sum

Feedback knock correction



Try to log all driving and verify that IAM makes it to 1 after the reset. Continue to log all driving in hopes of capturing the IAM drop or where a significant amount of low load knock is occurring.


If the weather has been extremely cold, it could be IAT compensation tables for various parameters are off and you're hitting some cells you may not have in the past.

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