TDog

Hi Guys,

I had this 383 LT1 built about 5 years or so ago and now have around 8,000 miles on it (Drive it on occasion) ...

I replaced the opti not too long ago due to a high RPM miss/backfire ... Got all of that straight ...

Over the past few months I've been noticing a miss or spark knocking sound (pinging) every now and again whenever I'm under medium to heavy throttle ... and have even noticed a puff of smoke from the exhaust before during this happening ...

I originally thought this could be bad gas but I still notice it from time to time no matter where I purchase my 93 octane or if I even use some octane booster.

It's been a while since I've changed my plugs and wires and I'm planning to pull the plugs this weekend and check them out ...

I get no codes and the engine drives and idles fine ... Just the occasional spark knocking under load ...

Any other ideas, than plugs/wires ??? Can a PCM tune need updating as the engine gets more miles on it and things wear?

Thanks!

marshall93z

Take a little timing out wherever it's doing it and see if it goes away.

<Puck>

+1, also be sure to check your plugs like you mentioned.

Octane booster in a bottle is useless as well - you need to use actual race gas to chase pinging problems. The "10 points" of octane boost they advertise is not in actual octane points, but there own measurement where 10 points is equal to one US ocane rating(RON/MON).

A whole bottle may make your 93 octane gas into a whopping 94 octane - and of course no difference would be noticed.

Injuneer

Have you ever done a data log/scan to determine if the PCM is retarding the timing in response to knock? If your knock sensor is still functioning, and the PCM hasn't been reprogrammed to desensitize the knock sense/retard process, you should never actually hear knock. The knock sensor should pick it up before you can hear it, and the PCM will pull timing to prevent it.

marshall93z

My POS knock sensor doesn't pick up ****. I hear before the sensor does, then I let out of it.

Maybe I should replace the sensor?

TDog

Sorry I haven't responded in a while ... I don't drive the car very ofter and don't always notice the issue ... but I have yet again ... I replaced the plugs and wires ... didn't help ...

And to answer Injuneer ... no, I haven't data log/scan to determine if the PCM is retarding the timing in response to knock ...

Maybe my Knock senor is no longer working and by swapping it out for a new one, the knock will go away ...

Is there any issues with swapping out my old knock sensor for a new one???

thanks!

SSQATCH

Should not be an issue except I believe the OBD2 and OBD1 knock sensors were different - but I could be wrong. Coolant will come running out when you remove them so you might want to be ready for it.

TDog

Maybe I've developed a Carbon build up over the years (tuned rich) that has raised, the already high 12 to 1 compression ratio, up further to where I'm getting this pimping/spark knocking while driving on 93 octane ...

Should I try some seafoam ????

I've got a slot set up for next week to run this car on the dyno and see if we can spot anything ...