Audible Ping?
Thread Starter
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
Audible Ping? I've been tuning my WOT AFR with a Wideband after my LT install. I'm currently at 12.6-12.8 throughout the rev range, but I seem to hear an audible ping. I do show some KR, which has always been typical of this car, but it has been less than usual. It only spiked to 2.8* and declined, whereas before it would often spike to 3.9*.
When I went to 13.1-13.5 it sounded more pronounced, and at 11.5-11.8, I didn't hear it. On manifolds, I never heard anything. Am I just picking up noise better because of the LT's? Any other ideas?
When I went to 13.1-13.5 it sounded more pronounced, and at 11.5-11.8, I didn't hear it. On manifolds, I never heard anything. Am I just picking up noise better because of the LT's? Any other ideas?
It's pretty normal to hear any persistent knock. You don't have a 98, so sensors aren't at question here, why not just tune it out? You will certainly run stronger with no KR, regardless of where you end up timing-wise.
Thread Starter
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
Thanks. The fact that I never heard it before has had me concerned, and especially that it continues to occur with a relatively fat AFR.
Since KR is intermittent and usually decays quickly, it surprises me to that it'd be better just to take the 4* of timing out of areas that are typically affected.
Since KR is intermittent and usually decays quickly, it surprises me to that it'd be better just to take the 4* of timing out of areas that are typically affected.
If the long tubes are doing their job, you are extracting more
hence filling with a fresher charge next intake stroke. The
charge is then more potent, burns faster and stronger. So
more pressure pulse (to make noise) and less timing needed.
I believe you can get audible ping without knock detect. The
knock detect uses blanking to suppress non-spark-knock (it
thinks) signal, it only looks where it expects to find spark
knock. If you had actual dieseling or preignition it might not
even notice (and since these have no relation to spark it
would have no authority anyway). Not saying dieseling is
actually present, but if you hear it, fix it - regardless of
whether the PCM agrees with you.
People say you can get knock with fatter mixtures and have
it go away at a somewhat leaner "sweet spot". I dunno. But
I wouldn't consider excess fueling to be a good cure, unless
you are forced induction. Otherwise I'd stick with the usual
"conventional wisdom" mixture targets and take out spark
until it shuts up or gets slower.
hence filling with a fresher charge next intake stroke. The
charge is then more potent, burns faster and stronger. So
more pressure pulse (to make noise) and less timing needed.
I believe you can get audible ping without knock detect. The
knock detect uses blanking to suppress non-spark-knock (it
thinks) signal, it only looks where it expects to find spark
knock. If you had actual dieseling or preignition it might not
even notice (and since these have no relation to spark it
would have no authority anyway). Not saying dieseling is
actually present, but if you hear it, fix it - regardless of
whether the PCM agrees with you.
People say you can get knock with fatter mixtures and have
it go away at a somewhat leaner "sweet spot". I dunno. But
I wouldn't consider excess fueling to be a good cure, unless
you are forced induction. Otherwise I'd stick with the usual
"conventional wisdom" mixture targets and take out spark
until it shuts up or gets slower.
Thread Starter
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
I think you're right about getting more audible ping without knock detect. That seems to be exactly what I'm experiencing.
I know that the deadly zone for KR on my car is 2nd or 3rd gear at 4200-4800 rpms. Higher octane has never helped. It improved somewhat with the LS6 intake !EGR. This is probably the range where pre-ignition is most likely to occur.
I don't hear audible ping in first. Second or third, yes. I think I'll start by taking out a couple of degrees in the "dyncylair" danger zone in that rpm range.
I know that the deadly zone for KR on my car is 2nd or 3rd gear at 4200-4800 rpms. Higher octane has never helped. It improved somewhat with the LS6 intake !EGR. This is probably the range where pre-ignition is most likely to occur.
I don't hear audible ping in first. Second or third, yes. I think I'll start by taking out a couple of degrees in the "dyncylair" danger zone in that rpm range.
Remember, even if the knock shows up as KR and like the full -4deg, that doesn't mean that you will need to pull that much out to get it to go away. -2 will likely do it for you.
For tuning I have decreased the knock attack rate and
increased the decay rate, this makes it a lot less over-
the-top and lets you see the real knock detect action
as it tends to be real-time, "motorboating along" at the
level of barely-detected-knock. This is a lot more useful
when histogramming for timing adjustment, you are not
looking at a whole bunch of "ancient history" covering up
the knock-in-the-moment. I think I'm at half attack,
4X decay from stock settings.
increased the decay rate, this makes it a lot less over-
the-top and lets you see the real knock detect action
as it tends to be real-time, "motorboating along" at the
level of barely-detected-knock. This is a lot more useful
when histogramming for timing adjustment, you are not
looking at a whole bunch of "ancient history" covering up
the knock-in-the-moment. I think I'm at half attack,
4X decay from stock settings.
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Originally Posted by jimmyblue
For tuning I have decreased the knock attack rate and
increased the decay rate, this makes it a lot less over-
the-top and lets you see the real knock detect action
as it tends to be real-time, "motorboating along" at the
level of barely-detected-knock. This is a lot more useful
when histogramming for timing adjustment, you are not
looking at a whole bunch of "ancient history" covering up
the knock-in-the-moment. I think I'm at half attack,
4X decay from stock settings.
increased the decay rate, this makes it a lot less over-
the-top and lets you see the real knock detect action
as it tends to be real-time, "motorboating along" at the
level of barely-detected-knock. This is a lot more useful
when histogramming for timing adjustment, you are not
looking at a whole bunch of "ancient history" covering up
the knock-in-the-moment. I think I'm at half attack,
4X decay from stock settings.
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Originally Posted by RevGTO
I think you're right about getting more audible ping without knock detect. That seems to be exactly what I'm experiencing.
I know that the deadly zone for KR on my car is 2nd or 3rd gear at 4200-4800 rpms. Higher octane has never helped. It improved somewhat with the LS6 intake !EGR. This is probably the range where pre-ignition is most likely to occur.
I don't hear audible ping in first. Second or third, yes. I think I'll start by taking out a couple of degrees in the "dyncylair" danger zone in that rpm range.
I know that the deadly zone for KR on my car is 2nd or 3rd gear at 4200-4800 rpms. Higher octane has never helped. It improved somewhat with the LS6 intake !EGR. This is probably the range where pre-ignition is most likely to occur.
I don't hear audible ping in first. Second or third, yes. I think I'll start by taking out a couple of degrees in the "dyncylair" danger zone in that rpm range.
TECH Enthusiast
Joined: Jan 2005
Posts: 658
Likes: 0
From: wisconsin
ya i have a 02 z28 sunset orange mett like yours and
running 92 oct the bestt i can get is about 21 degrees
before i here the audible ping what scares the hell out
of me.. now 21 = ok 25-27 bad ........................
but now i addad a 3ich cutout and now i loose power
on bottom and gain alot more after about 3800 rpm
any one want to talk about back pressure,,,,,,,,,,,,
and by the way i had to change timing , because
i changed the fueling all over from 11.5 to 13.3
cound not get ride of ping 60 dgr intake and 92.oct
i had to pull on the timing to take care of it..
now seams to be fine at diff intake temps at wot...
running 92 oct the bestt i can get is about 21 degrees
before i here the audible ping what scares the hell out
of me.. now 21 = ok 25-27 bad ........................
but now i addad a 3ich cutout and now i loose power
on bottom and gain alot more after about 3800 rpm
any one want to talk about back pressure,,,,,,,,,,,,
and by the way i had to change timing , because
i changed the fueling all over from 11.5 to 13.3
cound not get ride of ping 60 dgr intake and 92.oct
i had to pull on the timing to take care of it..
now seams to be fine at diff intake temps at wot...
Last edited by zrater; Aug 30, 2007 at 08:06 PM.
Thread Starter
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
Originally Posted by SSpdDmon
What kind of timing are you running in that range? I couldn't run more than 19* there with my '02. Since you have those heads, you may have to dial timing back.
Looking at a bunch of logs from the strip, rarely is there KR in first, frequently in second, and always in third -at the same airflow rates and MAP range in each gear.
Hopefully I'm going to the strip tomorrow night. I'm going to knock it down a couple of degrees throughout that range, log it, and look - and listen.
Originally Posted by RevGTO
I'm running the stock 00 timing table which calls for 26-23* in the offending range.
Looking at a bunch of logs from the strip, rarely is there KR in first, frequently in second, and always in third -at the same airflow rates and MAP range in each gear.
Hopefully I'm going to the strip tomorrow night. I'm going to knock it down a couple of degrees throughout that range, log it, and look - and listen.
Looking at a bunch of logs from the strip, rarely is there KR in first, frequently in second, and always in third -at the same airflow rates and MAP range in each gear.
Hopefully I'm going to the strip tomorrow night. I'm going to knock it down a couple of degrees throughout that range, log it, and look - and listen.
Thread Starter
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
I ended up taking 2* out of the trouble zone and went to the track for test and tune night. I made two series of passes, pretty much hot lapping it. I did not hear any audible pinging at any time.
As for KR, on my first pass, the usual 3.9* kicked in right on cue at about 4600rpm in third. However, on the next pass, I only saw a max of 1.8*, again, only in third. The third pass was like the first.
I let the engine cool for a while and added some Octanium to my fuel (we only get 91 octane around here). I had zero KR on three out of four runs, and 1.1* on one.
So it seems like a little less timing and a little bit more octane is the cure to my problem.
As for KR, on my first pass, the usual 3.9* kicked in right on cue at about 4600rpm in third. However, on the next pass, I only saw a max of 1.8*, again, only in third. The third pass was like the first.
I let the engine cool for a while and added some Octanium to my fuel (we only get 91 octane around here). I had zero KR on three out of four runs, and 1.1* on one.
So it seems like a little less timing and a little bit more octane is the cure to my problem.
