Unusual amounts of knock at unusually low timing

[Danspeed1]

so far all you know is "there is a noise" and "your knock sensor filter doesn't discard the noise (probably because its loud)"

i really dont see where the ignition timing theory comes from

I'm with you Steveo, but what concerns me is the fact that the noise only occurs at WOT and sounds exactly like knock lol. I am not totally even sure how to diagnose it to be honest. I could try getting the car up on a lift and do a quick pull but the noise could disappear or change without the weight of the car. It sounds like its coming from the engine, but its a fresh rebuild done by a professional shop. And its not like anything else I've heard. Ill keep messing with it and post my results. On the bright side, plugs look great, not indicative of knock at all. So close to getting this thing done; one step forward to steps back.

Dan

[Danspeed1]

Guys,

Just had a free moment to get back on this project. Just wanted to provide a quick update. The knock is definitely false. Now I have to figure out what could be causing it. Disconnected the knock sensor and did a run with it. Its actually running worse, at WOT it immediately pulls 6 degrees every single time. I don't know if that's possibly a fail safe or if there is an issue but i am going to start checking wiring and such.

If anything comes to mind, please feel free to post.

Dan

[ony]

what kind of hardware are you using to reprogram with?

[Danspeed1]

I am using a moats autoprom APU1 and Tunerpro RT.

I had a spare Knock sensor so I swapped it. Still doing the same thing. Doesn't even matter if its connected, as soon as I blip the throttle it pulls at least 5 degrees. Looked into changing out the ESC module, however on the 1990 its part of the ecm?

Dan

[steveo]

a knock sensor code in most gm ecms does some amount of additional timing retard... disable the code probably fixes that. alternatively you can zero the maximum knock retard and leave the sensor?

[Danspeed1]

a knock sensor code in most gm ecms does some amount of additional timing retard... disable the code probably fixes that. alternatively you can zero the maximum knock retard and leave the sensor?

I didn't know to remove the knock sensor code, so I'll give that a try. I'm assuming it's under the flags menu? I can reduce the maximum knock retard. It's not ideal because If real knock occurs there will be little safety net, but under the circumstances I dont think I have much of a choice. I'll give this a try next week and report back.

Thanks guys!

[steveo]

although it's nice to have, you don't need a knock sensor if you have consistent fuel quality, combustion chamber temperature, and run reasonable timing advance that isn't too close to the limit.

the more you modify an engine, the more likely it is that the knock filter will no longer work properly, and that sensor goes in the garbage.. although some ecms have a bit more ability to tune knock retard out of a certain range, so if you have localized false knock you can still have knock detection in other ranges.

if you can zero the max timing retard, that allows you to keep the sensor for knock count logging without actually turning your car into a marshmellow every time it thinks there's knock.

[Danspeed1]

although it's nice to have, you don't need a knock sensor if you have consistent fuel quality, combustion chamber temperature, and run reasonable timing advance that isn't too close to the limit.

the more you modify an engine, the more likely it is that the knock filter will no longer work properly, and that sensor goes in the garbage.. although some ecms have a bit more ability to tune knock retard out of a certain range, so if you have localized false knock you can still have knock detection in other ranges.

if you can zero the max timing retard, that allows you to keep the sensor for knock count logging without actually turning your car into a marshmellow every time it thinks there's knock.

I agree with you, I think we are there. I know a lot of people will disagree with removing the knock sensing capabilities, but at this point I've tried to make it work and I'm out of options so the next best thing is a little richer fueling, no knock retard and Sunoco 93 octane gasoline. I would feel worse about this if it was forced induction but if the car was 10 years older anyway It would have the same SBC and no knock sensor or computer. Never broke any of my carb'd cars....

Thanks for all the advice. This car has definitely been a learning experience

Also your statement about marshmellow made me laugh... that's exactly it, it goes soft the minute you step on it!

thanks again,

Dan