c6 Z06 LS7 Knock retard False Knock ??!

[hy_bmw_freak]

Hello guys i need your Help My car has a lot KR i don't know what the problem is.
Car has approx 45k miles and has H/C/I and Tune from katech i dont change anything, and the car runs fine, but for the past 6 months i have had issues with KR.

I don't drive so much often, approx. 2?3k miles in the year with this car, and i run only 102 octane pump gas fuel ( in USA, like 97?98 octane)

I Already changed all spark plugs and checked the spark plug wiring.
And make compressions test it was very good on all cylinders over 15 bars!!!

Thanks a lot for your support.

Greetings form germany

[rabbs88]

Post your tune as well

[hy_bmw_freak]

Sorry I forgot, but I can say it's not the tune fault !? Because I have older log without any KR. C6 Z06 Halil Katech Original Datenstand#.hpt

https://drive.google.com/file/d/1WFV...ew?usp=sharing

here is my old log same tune what I see is my car is running a lot leaner than before in this log i don't logged the AFR with hp tuners because I was to dump for this at this time.

But what I saw it's approx from 79-81.

I think It has issues with the fuel pump on this car !!

[edcmat-l1]

Do you have a catch can on the car?

First thing I would do is an "induction service". Suck some Seafoam into the intake while running. It'll clean all the oil out of the intake and de-carbon the cylinders, tops of the pistons. Then blow the engine out good. See if that doesn't fix it.

If it doesn't have a catch, put one on it.

[Alvin]

Hello guys i need your Help My car has a lot KR i don't know what the problem is.
Car has approx 45k miles and has H/C/I and Tune from katech i dont change anything, and the car runs fine, but for the past 6 months i have had issues with KR.

I don't drive so much often, approx. 2?3k miles in the year with this car, and i run only 102 octane pump gas fuel ( in USA, like 97?98 octane)

I Already changed all spark plugs and checked the spark plug wiring.
And make compressions test it was very good on all cylinders over 15 bars!!!

Thanks a lot for your support.

Greetings form germany

Sometimes they just go bad. Have you tried a set of new GM knock sensors. Don't buy anything else.. Beware of counterfeits on amazon and ebay.

I assume you don't hear any knock audibly?

[JayRolla]

Do you have a catch can on the car?

First thing I would do is an "induction service". Suck some Seafoam into the intake while running. It'll clean all the oil out of the intake and de-carbon the cylinders, tops of the pistons. Then blow the engine out good. See if that doesn't fix it.

If it doesn't have a catch, put one on it.

The old seafoam trick. I remember when I was young and tuning peoples DSM's I would do this all the time. My neighbor used to get so mad saying I was destroying the environment. HAHA. Another reason I love e85. Pistons and valves stay so clean, unless direct injected.

[edcmat-l1]

The old seafoam trick. I remember when I was young and tuning peoples DSM's I would do this all the time. My neighbor used to get so mad saying I was destroying the environment. HAHA. Another reason I love e85. Pistons and valves stay so clean, unless direct injected.

It's about the only chemical "fix" I've seen that actually works.

[hy_bmw_freak]

Thanks a lot for the support guys
I already checked my msd Intake and resealed.
Yes I have already catch can.

But I would say the failure goes in right fuel pump for me bc knock comes always if the lambda goes to like .90 and on my old logs car runs a lot richer and my heads are milled too

I will order new gm fuel pump and change both oem knock sensors.

[hy_bmw_freak]

No I don't here any knock sounds the car is to load for this but a feel the powerlost and car runs like it has fueling issues

[edcmat-l1]

Judging by the narrowbands it looks plenty rich enough not to be knocking on 97 octane fuel even if it's higher compression. It by no means looks lean.

[hy_bmw_freak]

Judging by the narrowbands it looks plenty rich enough not to be knocking on 97 octane fuel even if it's higher compression. It by no means looks lean.

yes i know but do you see my old log ?? it runs a lot richer but i dont know if is that the problem or not...

[Lakegoat]

Looks a little lean

[hy_bmw_freak]

Looks a little lean

Why you can't see my wideband log ???

[edcmat-l1]

Judging by the narrowbands it looks plenty rich enough not to be knocking on 97 octane fuel even if it's higher compression. It by no means looks lean.

When I posted this ^^^^ I had looked through his 250 pids for a wideband and couldn't find it. That's why I referred to the narrowbands.

Looks a little lean

After reading this I went back and looked again and yes it looks leanER than it's commanding and leanER than I'd like it to be.

What concerns me even more is the amount of timing commanded right around peak torque. My opinion it's a FEW degrees too much ESPECIALLY for a higher compression LS7 EVEN on higher octane fuel. It's commanding 25.5 degrees at 4000 RPM. I'd bet on a dyno it would stop gaining at 21 degrees at that point. I haven't looked at the tune file but the data log looks like the timing peaks at peak tq. and then goes back down. Typically the opposite of what you'd normally do which is roll the timing back at peak torque and then back in after you pass through.

I'd drop the timing through peak tq. for sure. By 4 or 5 degrees. The combo of both too much timing and little lean on fuel is the kiss of death. I pray for OPs ring lands LOL

total timing.jpg

[STAGEUP]

Im jealous at the amount of advance some of these LS7s are seeing in places with better fuel. Unfortunately, here in phoenix, our 91 octane is basically piss water. I typically max out at 18-20* advance on LS7s with H/C/I on 91 octane. In the middle of the Phoenix heat (110-118 degrees ambient), most of the H/C/I LS7s see about 14-16*s after the IAT does it job. So sad

[JayRolla]

Like edcmat has said have you tried to pull say 4-5* timing out around the 3600rpm and up just to see if it helps with the knock. Might be a bit spicey at max tq even with the octane.