Timing transition causing ping?

[HQforme]

I've recently been getting ping at 5500rpm and up, WOT, only 24 degrees total timing. It has done this a bit off and on for a while and i can't find a constant as it comes and goes. Aussie fuels are notoriously average so i put a lot of it down to that. Our 98 is more like your 92 or so. I throw some octane booster in for the drags. I'm thinking though that it's worsened by the timing curves?

Rolling up to say 3000rpm, 2nd gear before hitting the throttle the car runs near 40degrees as it's still factory timing down there. I'm wondering if that high initial timing "at the hit" so to speak can cause a little spike in cylinder pressure/temp etc?

Motor is an Ls1, 11.3/1 static, 236/242 hydraulic, ported factory heads, FAST manifold etc etc. 4500 stall TH350. 3.9 gear. 26inch tyre. AFR 12.8s. Air temp 50.

See attached log at 1min mark for the above described short pull. Minimal log channels as i'm suffering that bug where no matter what channels you send to MPVi2 it only logs the basics.Current best tune primary.hptLog-0024-6H8VTK69FYL514607.hpl

[SiriusC1024]

Hard to tell since this ping isn't registering on the knock sensors.

[HQforme]

Hard to tell since this ping isn't registering on the knock sensors.

It rarely does, but is a clear audible ping at consistent rpm range mentioned, on the pull logged. I think someone may have turned down the sensitivity on the knock sensors, or maybe they're not great for picking up a ping? It's only ever logged and pulled a few degrees timing in the burnout box on a hot day with heat soak.

[SiriusC1024]

Goes away with octane booster? Lower the timing a bit. That timing in the 40's is extended out a bit to 0.3g. Usually all that is pulled back to 0.15-0.20g.

[HQforme]

Goes away with octane booster? Lower the timing a bit. That timing in the 40's is extended out a bit to 0.3g. Usually all that is pulled back to 0.15-0.20g.

Indeed it does but the thing which gets me is that it wasn't pinging before. Gets driven regularly and AFRs are good so it's not carboned up. I've already made a few tweaks to the timing, pulling a bit through the sweep (going by rpm/air mass) from that steady state throttle to full noise and gave it a smidge more fuel to be safe. Shorted the PE mode engage time a tad, again to be sure. One area i've not delved into is transient throttle; the old pump jet equivalent. Could help, though there's no lean spike registered when i log AFR. Will test this weekend.

Thanks for the input!

[SiriusC1024]

Anything to do with high IAT and adjustments to the IAT spark that have been made?

Running open loop, and it shows rich in the log. Are you sure about carbon? Is there an equivalent to seafoam or marvel mystery oil down under? Have you tried STFT at least or STFT/LTFT? I don't see the sense in running open loop, personally. You're not running some wild donkey dick cam in that thing.

Maybe need new plugs. Might try ones with a lower heat rating.

[HQforme]

Anything to do with high IAT and adjustments to the IAT spark that have been made?

Running open loop, and it shows rich in the log. Are you sure about carbon? Is there an equivalent to seafoam or marvel mystery oil down under? Have you tried STFT at least or STFT/LTFT? I don't see the sense in running open loop, personally. You're not running some wild donkey dick cam in that thing.

Maybe need new plugs. Might try ones with a lower heat rating.

I've long since zero'd out anything in the IAT modifier table, that was only pulling timing anyway. Same with ECT. You're saying the narrow bands show rich? The wideband in the car reads excellent numbers. Recently replaced the sensor, calibrated a month ago. There are top end cleaners here i can try. Just pulled the plugs (heat range 7s), they don't look rich but i can see tiny aluminium deposits from the ping. Not cool. Top of the piston is pretty carboned up. I'll try get a bore scope in there.

Car is open loop as i bought the computer with a tune in it and started working from there. My first EFI car. I'm still more familiar with modifying emulsion tubes than ECU tables but i'm getting there. Will try fuel trims once this is sorted.

Ultimately we're in winter and it should be happier but i ran all summer without issue, now this!

ECU is a little iffy at times. Randomly changes 1/2 point AFR at idle and picks up rpm; not just a fluctuation, a clear change in constant reading from lean at idle to rich at cruise but it goes away. Have chased TPS noise, re-wired the ECU, done all the checks.

[SiriusC1024]

High comp engine with aggressive spark and safeties modified/removed. That tune is in 'send it' mode, and you're seeing the effects.

Idk why it just now occurred to me. You speculated that the ping happens on the punch. I'm seeing Burst Knock Retard vs RPM has been zeroed out. I'd put that back. How much total power will be lost by pulling timing for a fraction of a second? How much engine longevity gained? Also, tip-in knock sensor levels have been increased, which makes the knock sensors less sensitive.

Zeroing out IAT spark modifiers, especially since you have high IAT's, is counter-intuitive.

I really think you should scale back the spark like I mentioned earlier. A 2005-2006 GTO file would be an excellent reference, as that seems what the spark profile is based on.

Yes, the narrowbands show rich and unbalanced. Please, please, put it back into closed loop. Engine>Fuel>Oxygen Sensors>Closed Loop Enable. Go a step further in the right direction by re-enabling LTFT's. Bonus points for getting Lean Cruise working well with your setup.

Ur car on open loop:
OL tards.jpg

[HQforme]

High comp engine with aggressive spark and safeties modified/removed. That tune is in 'send it' mode, and you're seeing the effects.

Idk why it just now occurred to me. You speculated that the ping happens on the punch. I'm seeing Burst Knock Retard vs RPM has been zeroed out. I'd put that back. How much total power will be lost by pulling timing for a fraction of a second? How much engine longevity gained? Also, tip-in knock sensor levels have been increased, which makes the knock sensors less sensitive.

Zeroing out IAT spark modifiers, especially since you have high IAT's, is counter-intuitive.

I really think you should scale back the spark like I mentioned earlier. A 2005-2006 GTO file would be an excellent reference, as that seems what the spark profile is based on.

Yes, the narrowbands show rich and unbalanced. Please, please, put it back into closed loop. Engine>Fuel>Oxygen Sensors>Closed Loop Enable. Go a step further in the right direction by re-enabling LTFT's. Bonus points for getting Lean Cruise working well with your setup.

Ur car on open loop:
OL tards.jpg

The IAT retard was removed to set the max timing at the drags with no modifier tables in play, logging IAT to see if the car entered the temps where it would retard timing, which it didn't. I still have stock tables to put in, i just hadn't as it'd never pinged or showed retard there before. Unless of course what was in there was already modded and reduced in terms of safety retard? I'll put burst knock retard back in. It's something i've never touched so didn't realise wasn't there.


I didn't speculate it occurred on the punch, i speculated cyl pressure was spiked by the high timing and that lead to a ping higher up. The punch is at 3, the ping is clearly later on, 5k and up, well past the PE enrichment, into full WOT parameters.

I'll put CL back in, that's always been a goal, tune OL as close as possible before enabling.

Thanks again for the input mate. Nice to see you got my good side in the photo.

[SiriusC1024]

Haha

Hope you get it sorted.

[HQforme]

Well...................... had a look with the bore scope.

2468 are ok but show clear signs of detonation. Lunar surface and all. 1357, 1 and 7 are oil fouled to shit. 3 and 5 are same as 2468.

Comp test is immaculate so it's in my heads.

i'm thinking this thing has had light detonation for a while that you simply can't hear over twin 3inch dumped at the diff and the reduced sensitivity/no burst knock has let it run free a bit.

[SiriusC1024]

Yeah man. Spark is aggressive and knock sensors have been desensitized.

As far as the oil leaks, did you forget to seal the rocker bolts with rtv when you installed them? The threads become exposed to the intake air stream after port work.

[Alvin]

Very bad idea zeroing out timing modifiers for ECT and IAT.

[HQforme]

You're correct but i made sure to seal them. I did run an old school knurl through one marginal guide. Rumour has it they can wick oil on a big decel. But that was only 1cyl.

Please inform me which parameters to change to ensure the knock sensors are back where they should be?

[SiriusC1024]

I'm having trouble with looking up the VIN to compare knock values. Says Holden Commodore, but what's confusing is that the tune has 5.7L at General>Engine. Thought those had a 6.0? What year and engine please?

I can see loose valve stems combined with the side thrust of a high lift cam compromising the valve seals. Also, did you use brown valve stem seals on the exhaust, black on the intake? And the rtv...on the actual female threads not under the head of the bolt. Just checking to be sure. It's easy enough to pull a rocker off and check the bolts for oil. While you're in there look for cracked/torn seals or those missing the control spring wound around the lip. For possible excessive PCV residue, open the throttle blade and take a look down the snout of the intake. There are the only 3 places oil can come from - rings, valve stems, PCV. Smoke on deep decel would be valve stems.

[HQforme]

They had 5.7s with the first gen LS powered cars from about 98-04. It's from a 2000 5.7 commodore but now a built motor in a swapped car so whatever you think is appropriate?

You're correct on all fronts and i did all as described. You'll fall out of your chair laughing when i tell you where the oil came from. Suffice to say I'm a damn fool! I rigged a line from a catch can drain tap to a vacuum port when i was going for engineering as a pseudo pcv. Knowing it wouldn't actually work i just had the drain valve closed. Only...... when i just checked then, it's open. Hello oil slick in manifold. Hello tuned around a vacuum leak. Hello what a stupid mistake to make. Oh well.

[SiriusC1024]

Vacuum line on the catch can drain lmao. You don't have a factory PCV with a catch can inline or...what is even going on with that pseudo PCV rig lol?

Still, nice find on the oil source. Oil in the cylinder will increase chances of pre-ignition; however, we still shouldn't neglect knock sensor values. Knock should be detected and arrested way before it can be heard.

Funny, I had actually pulled a 2000 Holden Commodore from the repository yesterday when I wrote. It didn't look laid out like your tune file. Figured out why that is. The ECM, or at least the OS, in your car is from a 2002-2004 Commodore. The OS number in your tune matches those, and the tune configuration matches.

What's been hurting you the most is the Knock Sensor Global Gain table. It's really hard to say what adjustments should be made to knock-related values. 2000 Commodore looks suspiciously low. 2004 Commodore looks kind of high. 2001 Camaro doesn't quite fit. All LS1's, but such different values.

Attached is what I've come up with.
- Engine>Spark>Knock Sensors
- Engine>Spark>Retard
- Engine>Spark>Advance>IAT Spark

I kept in mind that knock has been present but not detected while trying to make changes that avoided over-sensitivity. Your guess is as good as mine.

[HQforme]

Aplogies, haven't been on here or working on the car. Now things have settled i'm back at it.

I have no PCV. This setup was an interim as i have stack injection to go on so i set up with no PCV, just a catch can (again, old school crap). I did the dummy setup mostly so if i got pulled over it looked like a recirculation of the gases (legal requirement here in Aus). I played silly games and won a prize

Ah, thanks for the sleuthing! So when i bought the used motor it has a tune, from a shop, so i just trusted what was there. I had no idea about EFI in any way. I rebuilt/improved the motor and started to learn how to tune VE and went from there. Makes great HP, runs good numbers. This is the first major issue.

I've started the tune again (minus vacuum leaks). Took a full point of base running air to get it back to where it was. Now i'm battling the false reading on the 02 from the cam (110 sep) as at stoich it's rich as all hell. Lean it out to say, 16 and the bloody thing idles like a rotary. Not having that!

I'll let you know how she goes once driving. Again, very much appreciate the time and effort.

[HQforme]

This thing took 2 g/sec of base running air to get happy again! Then all the VE work was about 5-8% out in light throttle work/cruising. She's back to running sweet at light loads and i went old school on my idle tuning, chasing clean plugs and a happy idle at an indicated 16/1. Lends weight to the theories of false idle AFR readings with larger overlap cams. Interestingly it made slightly more vacuuum with the fat idle but was pig rich at an indicated 14.7. Now responds better to snapping the throttle on free rev and settles beautifully.

Next drive will start hitting PE and WOT.

[SiriusC1024]

Nice. What did you come up with for the knock sensors?