S52 OBD1 slight pinging

[MatRacer]

Hi,

Here is my setup:

1998 S52 with about 100k miles
OBD1 intake and DME
24# injector
3.5 MAF
OBD 2 exhaust manifold
LTW UUC Flywheel
OBD1 Turner chip for the 3.5 MAF, injector and ltw flywheel

Recently got the head machined flat. All the valves where clean and tight Rebuilded it with and OEM style HG.

Just noticed that I had little pinging between 4k and 5k RPM at WOT. nothing at part throttle, even at 3/4...It is not noticable in 2nd gear, it is slightly noticable in 3rd and more in 4th... havec tryed in 5th cause this would put me way too fast on public road...

could this problem be caused by my slightly higher compression ratio due the the head beeing machined flat...? Haven't measured it...

I don't have any CEL code
I don't have a wideband
Vanos seems good. It was operating just fine at 50psi with air
no strange noise at idle
Other than than run very strong

I have tryed Octane booster without success...
Will check the compression
Will recheck the timing
Will contact turner motorsport to have a chat with Doug regarding the head beeing milled a bit..

[ian e30 318is]

Are you sure its pinging and not your lightweight flywheel making noise? I would get a wideband AFR gauge in there as soon as you can. It'll give you an idea of whether you are running lean or not. Also could be the off the shelf chip from Turner.

[MatRacer]

Are you sure its pinging and not your lightweight flywheel making noise?

I'm not 100% sure it is pinging but really sounds like... however, I feal like pinging should be a bit louder... Never heard ltw flywheel noise... so not sure about that. Also, could be that since I feel that the sound is more coming from the engine rear end... but really not sure...

[MatRacer]

Would a ltw flywheel with sprung clutch discg really produce a little knocking sound at 4-5000 rpm at WOT? keep in mind that I absolutely have no sounds if i'm not at WOT...

[MatRacer]

My guest is that because the tune is for a 3 liter and that I'm running a 3.2 liter with a OBD1 intake and adding a little milling to the head may produce a lean condition at WOT combined with a slighty higher compression ratio leading to detonation... But really I'm not 100% but but sure sounds like... However, I do not feel any power loss or anything...
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