I've been cutting timing, adding fuel, decreasing attack rate, and increasing recovery rate. I can't get rid of spark retard!

I've made several runs and charted scan data to see where the problem areas are. It always occurs at the 4-3 downshift. A bunch of timing is pulled out and it gradually puts it back in. My "load" is constantly above 208 and the spark values are constant there. It's only in the first couple of seconds that knock is detected. The knock counts mysteriously stop and the spark advance is added right back in.

In other words. over a span of about ten data points (.5 sec apart) the load and requested spark are the same, but the knock counts quit even as spark is re-introduced.

What is it about the downshift that is causing knock to be detected? What changes can I make to address this?

BTW: TunerCat tells me that the spark is 13.4 there, but my scan tool says the spark is 14.3. Why the difference?

 

The knock sensor is an acoustic devise.
I just listens for noises of a particular frequency

I've never seen an engine detonate on decleration. Sounds like you have a exhaust rattle, or serpentine belt problem (to name a few)

 

It's not during deceleration. It's during acceleration. It's when I'm cruising at say, 50-60 mph and then step on the gas to pass someone. The transmission downshifts from fourth to third and immediately detects "detonation".

I tell you, I'm this close to disconnecting the G D knock sensor! ...uh, correctly, of course.

 

See if the code your running has the burst knock retard and what things are set at.

BTW, if you'd said forced downshift, would have had an idea of what you meant.

 

Burst knock retard... That sounds interesting. It's cool how you manage to subtly reveal secrets from time to time.

I'm using TunerCat's software and a $6E mask. I find no reference to burst knock retard in my version. If you know of such a table, I can contact TC and he'll probably reveal it for us.

Maybe this will be like that crank pulse ref pulse thing that solved hard starting problems for many of us.

 

<G>

 

That was odd.
The <G> disappeared.

 

Grumpy, I think you were trying to tell me something, but it didn't come through. You were going to solve my problem with this burst knock retard thing, right? :hail:

 

Would warrant investigation.