Is it real knock or something else?

[JT]

I have finished street tuning a 93 Prelude with a stock JDM H22a and USDM P72 ECU. The engine is running very smooth and strong. The fuel and ignition tables don't seem very aggressive. However, when trying to collect a few datalogs with the knock sensor on, I noticed the ignition timing was retarded due to knock detection. The engine bogged down as a result. I have read another knock related thead on the forum and a defective MAP sensor was suggested when the range went beyond 100kPa.

I have attached 2 log files and the calibration files for evaluation. The normal log file indicates the MAP sensor registering 102.6kPa at the very beginning. The ignition curve also has some strange activities.

The knock log file also indicates a high MAP reading at the beginning during the knock activities. It also registers knock activities at only 33% throttle input.

I have been noticing similar intermittent bog down problem even with the stock JDM P13 ECU, which potentially due to the same timing retard. Do you think the MAP or knock sensor is the problem? Perhaps the knock board on the P72 being overly sensitive for the H22a engine? Thanks for any inputs.

[Spunkster]

Have you tried disabling the knock sensor to see if it smooths the problem area out?

[JT]

No bogging down or hesitation when the knock sensor is disabled. In fact, it runs great. I'm just wondering if I should leave it disabed or try to find the root cause. Please see the attached log files.

[Spunkster]

Have you tried reducing the timing in the problem areas of the map?

[JT]

Yes, I have tried reducing the timing by 2 degrees from column 6 to 10 ( both low and high cam tables) with the same result (still detecting knocks). I then reduced the timing by 5 degrees, and later by 10 degrees with the same result. Not only that, it also registers knocks when I slightly blip the throttle in neutral to around 1200 rpm. I didn't think it should knock under such low load.

I also notice it only knocks during throttle tip-in regardless if the load is light (blip throttle in neutral), moderate (increase throttle input during cruising), or high (mesh the pedal). There's an "Ignition Compensation" tab in SManager with "throttle tip-in retard" and "TPS adjustment" with retard % values. Should I try changing the default values there? If so, what would be a good starting point?

[deafy]

I have the same issue, same more and same ecu. I was told the knock sensors from ludes have different signals than the gsr which is causing it to detect knock when there isn't any.

[JT]

The knock sensor itself is actually the same as the GSR (same part number), but the sensitivity might be different on the knock board inside the ECU. Since we can't adjust the knock board, there's probably not much we can do but to disable it.

I've been searching for another option to detect knocks and perhaps use it for tuning purposes. There's a product called "Knocklite" which has the capability to set the threshold at the different rpm range for filtering background noises, as well as sensitivity adjustments. It connects to an optional knock sensor if the existing sensor is faulty or inaccurate. I'm hoping the output of this device can be hooked up to one of the s300 inputs and datalog the activities.

http://www.turboxs.com.au/downloads/ins ... nstall.pdf