Detonating/knocking '00 3.4L V6.

2000 Olds Alero, 78K miles on the infamous 3.4L V6.
My girlfriends been complaining that the car is down on power. I threw new plug and plug wires at it. One plug wire was up around 13K ohms,
and the car DOES seem to run smoother. Air filter is recent. No new mice nests, etc. etc.
I pulled out my logging/editing software that I bought for my truck. It has the ability to do a pretty decent job at scanner any OBDII GM.
I saw that her manifold O2 wasn't responding as nicely as it should have, and her LTFT's (long term fuel trims) were low (rich) for a stock vehicle. I put in a new 02, and the LTFT's are a little better. Still on the rich side.
I logged some data while driving the other day. The car is getting TONS of Knock Retard. It's pulling upwards of 10 degrees from 2000rpm up. That's definitely one reason why the motor is weak feeling.
I didn't realize it, but you CAN hear the motor knock, so it's not false- knock getting picked up by the knock sensor(s).
Now, why the heck is this motor seeing this much knock? It's all stock. She runs the lower octane gas in it. I think it's 87 around here in the North East US.
I thought I heard something about some of the later GM V6's needed to be decarboned or whatever the terminology is. I also hear there's this "Seafoam" stuff that does a good job of doing that for you.
Anyone have any recommendations?
Thanks, -marc
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Inop egr system will cause pinging and spark retard as a result.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David J and Lynne J Shepherd wrote:

AWESOME CALL. I keep forgetting that the car threw an EGR code over the winter. I waited to see if it came back, and I just forgot about it.
Thanks, -marc
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.