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

19111

and the tune

19112

[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.

[jmsmotorsport]

1911319114 the two latest.

[jmsmotorsport]

1911319114 the two latest.

Well after going over a earlier log and a later one the histogram shows around 8 degrees max timing with 8 KR at wot and after taking some timing out it is now showing 17 max but still with 8 KR. If you look at the first bit of WOT in that log there is no KR and 22 degrees timing, next one cuts back to 17 and 8 KR

[joecar]

1911319114 the two latest.

Well after going over a earlier log and a later one the histogram shows around 8 degrees max timing with 8 KR at wot and after taking some timing out it is now showing 17 max but still with 8 KR. If you look at the first bit of WOT in that log there is no KR and 22 degrees timing, next one cuts back to 17 and 8 KR
Ok, I'm looking at these in more detail later tonite.

[jmsmotorsport]

Well we checked the knock sensors and the where they sit in the valley was full of water. I would imagine that would be playing tricks on the whole show.

[joecar]

Well we checked the knock sensors and the where they sit in the valley was full of water. I would imagine that would be playing tricks on the whole show.

Yes, correct.

[jmsmotorsport]

Well we have had a win, no more silly KR and the power is up where it should be. There is some minor KR shown in the quick log I did just with the V2 and no W02 to see if we fixed it, this has given me an insight into what real knock looks like on the histogram. Now its time to finish the VE table and tune out this knock for use with the 95 octane fuel. Thanks again for your help Joe, might make a tuner out of me yet. If only i could win some money and buy myself a dyno.

Here is the quick log for you to check out. 19118

[joecar]

Good job :cheers:

Comments:

B3609: set to 0.05 seconds in all cells.
B4001: looks wrong (should look like: IFR(x) = 3.5469 * sqrt((400+x)/400) where x is MANVAC in kPa and 3.5469 g/s is IFR at 58 psi).


If you're still tuning VE, then you have CL/trims enabled (B3801, B4205).

[joecar]

When logging, remove pids OS211/21 and instead log HO2S11/21.

[joecar]

Is your FPR un-referenced...?

[jmsmotorsport]

Thanks joe will set B3609 to 0.05 the other table B4001 I never touched that's how it was factory, I am a little confused with what you wrote regarding the FIR, fuel reg is the standard set up so un refrenced dead head set up (for at the tank)
Will change those 02 pods to the heated ones, that last tune was when I pet it back into open loop SD will go back to CL To finish the VE tuning.

[joecar]

Ok, FPR is unreferenced with FPR in gas tank (trucks usually have manifold-referenced).

First cell in B4001 is 3.5469 g/s, last cell should be 3.5469 * sqrt(480/400) g/s, and all the in-between cells should lie on the line in between...

i.e. 2nd cell should be 3.5469 * sqrt(405/400), 3rd should be 3.5469 * sqrt(410/400).

[jmsmotorsport]

Ok no problem, it's strange that all the stock tune files I have are fairly similar to this one. By sqrt I'm guessing you mean square root?

[jmsmotorsport]

So if I'm right the last cell should be 3.8854? That would be the 3.5469 Multiplied by the Square root of 480 divided by 400? Just making sure I'm following the way you have set it out and interpretating the symbols correctly.

[joecar]

Ok no problem, it's strange that all the stock tune files I have are fairly similar to this one. By sqrt I'm guessing you mean square root?


So if I'm right the last cell should be 3.8854? That would be the 3.5469 Multiplied by the Square root of 480 divided by 400? Just making sure I'm following the way you have set it out and interpretating the symbols correctly.

Yes, correct.

[jmsmotorsport]

This good, glad I have some sort of understanding haha. I used the calculator so I'm hoping it should be right, with the B4001 table set up correctly based on this maths will i then need to go and redo my VE?

[joecar]

Yes, redo VE.