Knock at WOT

[Epox4life]

I'm just starting to log data and I noticed I'm getting some KR at WOT. Also injector duty cycle shows 86% that seems high for a car with only intake manifold, throttle body, and cat-back exhaust mods.

My PCM is on a stock tune so what could be causing this KR? I attached the log file, let me know what you guys think. Thanks.

Updated: Added two extra logs one with less knock.

[Chevy366]

Not unusual to get knock in a stock tune at WOT , stock tunes are so generic and just close enough for all .

[ScarabEpic22]

Some I6 TrailBlazers have up to 5-6 degrees of knock!!! I have logs to prove it (somewhere...)

[mr.prick]

There's something not right about that log, was it filtered before it was saved?
LTFTs are high and positive during PE (7%) :eek: and
AD1&2 are stuck @ 3.4v-3.8v :confused: so no way to add WBO2 data if you had one hooked up.
Are stock tunes that bad? :hihi:

[Epox4life]

There's something not right about that log, was it filtered before it was saved?
LTFTs are high and positive during PE (7%) :eek: and
AD1&2 are stuck @ 3.4v-3.8v :confused: so no way to add WBO2 data if you had one hooked up.
Are stock tunes that bad? :hihi:

Completely stock tune and that log was not altered in anyway. Stock tunes are pretty bad commanded AF is 11.7!


Not unusual to get knock in a stock tune at WOT , stock tunes are so generic and just close enough for all .

Thats good to know, looks like I'm going to have to do a lot more reading and work on a tune for my car. Thanks guys!

[joecar]

11.7 might be cat overtemp protection kicking in.

[mr.prick]

That is stock PE ratio for a '98.
The positive LTFTs during PE points to more fuel being needed or
maybe Ethanol in the tank.
I filled up the other day and saw my LTFTs go positive,
making me believe I got more than I bargained for at the pump.

I have heard that 97-98 have inferior KR sensors too.

[joecar]

Oh, I see... I'll have to look more closely at a 98 file...

The 98's suffer from KS problems, constistant 4° KR... there is an upgraded KS and sub-harness from GM.

Altho his KR looks like it is sawtooth shaped indicating it might be real...

I have read about overly-rich spark knock, but I don't think this is the case.

[Epox4life]

That is stock PE ratio for a '98.
The positive LTFTs during PE points to more fuel being needed or
maybe Ethanol in the tank.
I filled up the other day and saw my LTFTs go positive,
making me believe I got more than I bargained for at the pump.

I have heard that 97-98 have inferior KR sensors too.

I am in the north east where we all have 10% ethanol at every pump, it sucks.

How much will having 10% ethanol in the gas change the tuning process? What things should I look out for because of this?

Added two more log files at the first post.

I was thinking doesn't torque reduction in the stock tune pull timing on shifts? Is that done by using KR or could it cause KR to happen?

[joecar]

TR just reduces timing to prevent knock... it doesn't cause KR to happen, and it doesn't use KR to reduce timing...

The value you see for the KR pid is in response to knock/noise being detected by the knock sensors... the PCM determines how intense it is and sets KR which is subtracted from the final spark advance (i.e. SPARKADV reduces by KR amount).

[mr.prick]

{B3601} should match the fuel you are using.
Air fuel ratio comparison (http://en.wikipedia.org/wiki/E85_in_standard_engines#Air_fuel_ratio_comparison)
E10 = 14.13AFR
Changing {B3601} will automatically change {B3605} & {B3618} as they are in EQ
and are based off {B3601}.

[Epox4life]

TR just reduces timing to prevent knock... it doesn't cause KR to happen, and it doesn't use KR to reduce timing...

The value you see for the KR pid is in response to knock/noise being detected by the knock sensors... the PCM determines how intense it is and sets KR which is subtracted from the final spark advance (i.e. SPARKADV reduces by KR amount).

Thanks for explaining that to me. Do you have any idea what could be causing the injector duty cycle to be at 85-90% in these log files?

[Epox4life]

{B3601} should match the fuel you are using.
Air fuel ratio comparison (http://en.wikipedia.org/wiki/E85_in_standard_engines#Air_fuel_ratio_comparison)
E10 = 14.13AFR
Changing {B3601} will automatically change {B3605} & {B3618} as they are in EQ
and are based off {B3601}.

I'm thinking I will change the PE value from .80 to .89. Do you think that would be good once I verify that the commanded AF is near the actual AF?

[mr.prick]

I wouldn't lean out PE unless you know what AFR actually is.
Getting LTFTs closer to 0% is something you can do w/o a WBO2.
They should not be positive during PE.

[Epox4life]

I wouldn't lean out PE unless you know what AFR actually is.
Getting LTFTs closer to 0% is something you can do w/o a WBO2.
They should not be positive during PE.

Alright I'll work on that first, thanks.

Edit: After reading a thread on E10 Fuel, I agree and think this is having some impact on my LTFTs.

[MikeyC]

Epox4life, did you get this problem rectified? If so, what was the fix?

[Dragframe]

wow didn't know the stock stuff was that off!

[Epox4life]

Epox4life, did you get this problem rectified? If so, what was the fix?

Never figured it out, ended up trading the car in just because I needed something more practical for a daily driver.

The knock would show more times than others for no apparent reason, it might have been due to 98's having inferior knock sensors.