Rauldelp

Odd problem here, that I'd really like to get sorted so I can call the tune "done". Engine is a 93 TBI from a Buick. I'm about to swap in a 7427 PCM, that might help, or this will follow me, I don't know.

As soon as I tip into PE mode, I get 4-5 knock counts. I could floor it, or slowly roll into it, I get 4-5 knocks and I hear it. Sounds like a hollow rattle.

I've reduced and increased my PE spark table. The SA table up and down as well. The VE map looks to be within 124-134 all across the map.

It used to do this more when you'd floor it, but I leaned out the AE (TPS and Map, factory map was very very rich) and that pretty much went away. Now I just have these 4-5 knocks.

PE is set to 12.5AFR, (according to the WB02 it's around 12.2-13.1) so that should be ok.

The really odd thing, all this started when I went to an open air cleaner. If I go back to the stock filter box, it's mostly gone (but of course the engine won't go over 89-91kpa on the Map sensor.)

Thanks in advance!

Dominic Sorresso

Rauldelp

I may be stumbling my way to the solution.

First I removed all PE spark advance. Just to take spark knock out of the equation. Knock/rattle stayed the same on my test loop.

I then increased AE TPS/ AE MAP by 50% in the low map, low tps positions. Knock is now 2-4, but the rattle was almost gone.

Another round of increasing AE in the low map, low tps another 25%, knock looks like 2, and the rattle is, except for one whisper, gone.

I'm not sure how much AE is normal, I'm currently way above the stock numbers in the low load region. Wideband is still reading the same with the new AE settings, it must occur too fast for me to see it on the gauge. Snaps to 12.5ish very quickly.

Here's the original settings:


Here's the current settings:

Dominic Sorresso