Knock DTC and Funny KR Readings at part throttle.

[jmsmotorsport]

Doing my Auto VE tune and keep getting this DTC,

P0327 Knock Sensor (KS) Circuit Low Frequency Bank 1 MPHC ($10) "Powertrain Control Module (PCM)"

I have also noticed that at around the 4000rpm range there is a shudder I am hoping it is just due to the afr at this point being commanded 12.5 but actual is 11.3. But going over my log at WOT and part throttle (enough to go into PE) i keep getting serious KR 8 degrees, timing is only set at 27 degrees @ 4000rpm 45 grams sec. I would have thought this to be very mild timing? using a 95 octane fuel.

here is the log

cmcindoemafless3.efi

and the tune

Chris M Mafless4.ctz

[johnv]

Sort your Knock sensor code first, ie replace sensors.
I wouldn't call 27 degrees @4000 rpm mild, depends on engine specs, but most bolt on or cam combos wouldn't take any more timing than that.

[jmsmotorsport]

Sort your Knock sensor code first, ie replace sensors.
I wouldn't call 27 degrees @4000 rpm mild, depends on engine specs, but most bolt on or cam combos wouldn't take any more timing than that.

Well I looked into it further and with the original tune I pulled from the PCM the file corrupted some how and wouldn't load back into the PCM so I got a factory tune file from tunefiledepot well all the knock sensor calibrations were different along with a lot of other parts. I agree that if at work and 4000rpm 27 is fairly high but this was only part throttle cruise. I also noticed that the original factory tunes timing was much more aggressive?

I will take another log tomorrow when it cools down (40 plus here today) and see what the KR is doing.

[joecar]

I haven't look at your log yet, but airflow 45 g/s at 4000 rpm is too low...

look thru your older logs and you would see MAF go to above 200 g/s at 4000 rpm (even at part throttle).

[jmsmotorsport]

I haven't look at your log yet, but airflow 45 g/s at 4000 rpm is too low...

look thru your older logs and you would see MAF go to above 200 g/s at 4000 rpm (even at part throttle).

Joe,

this is on a different car from before but in reality they are similar setups except this one is running a standard airbox. I am getting the g/s from the GM.CYLAIR_DMA PID is this the correct one to be using as the max reading I am getting is .68?

[joecar]

Ok, 0.68 g/cyl is about right for an NA car with a stock/mild cam.

[joecar]

Looks like your KS may need to be replaced (that does not look like real knock at all).

[jmsmotorsport]

Looks like your KS may need to be replaced (that does not look like real knock at all).

Who would have thought to different cars that I have fiddled with and both throw knock sensor codes. One just keeps it at 3 degrees constant as per the KR faulty setting and this one throws out random knock killing top end power. Thanks again joe glad your here to help me every time. 👏

[jmsmotorsport]

Well I pulled 4 degrees out from 4000 - 6000 between .45 to .70 g/cyl where the knock was and it did nothing, still pulling 8 degrees KR I guess that eliminates real knock being the timing is now 21-23 degrees? The owner has some new KS and Loom so will changed these and will log it again and see what its doing, hopefully it gets it sorted because the BEN is good and car feels smooth until the point it retards it so much it goes flat and wont even get over 95kpa at WOT in the 4800-6000 range.

[joecar]

Well I pulled 4 degrees out from 4000 - 6000 between .45 to .70 g/cyl where the knock was and it did nothing, still pulling 8 degrees KR I guess that eliminates real knock being the timing is now 21-23 degrees? The owner has some new KS and Loom so will changed these and will log it again and see what its doing, hopefully it gets it sorted because the BEN is good and car feels smooth until the point it retards it so much it goes flat and wont even get over 95kpa at WOT in the 4800-6000 range.

POst tune file and log file.