PDA

View Full Version : Knock from RPM's table.


whywoody
10-12-2009, 11:48 PM
I have been tempted to change this table,but would like some input please.
Reason being is,at differing rpm's/boost I have had no CEL light come on but hear knock,and other rpm's/boost the light comes on and not a hint of knock can be heard.Does this make sense lol?
This is with my 2.5ltr 16vdohc hybrid,with the knock sensor screwed into the flange between #3 and #4 intake runners.I thought here would be similar to the 2.5ltr T1 stock position.

I would like to understand how/why these values were originally chosen,especially why the voltage seen rises so much versus rising rpm's...I have been lowering the voltages accross the rpm range for a bit of 'safety' while I figure things out better.
whywoody
10-12-2009, 11:51 PM
This is the screen shot of what I'm refering to.
http://i288.photobucket.com/albums/ll189/whywoody/IMG_4335.jpg
turbo84voyager
10-13-2009, 08:23 AM
The best way atleast I was always told to come up with the correct values is you need a scanner and rev the engine in neutral to several different rpms and make note of the knock voltage. Then set the sensitivity just slightly higher.

The stock settings are quite sensitive since they are set for people using low grade gas. As for knock, I had a similar problem with my g-headed 2.5. It sounded like it had detonation but there was no CEL. After pulling the head there was no signs of detonation but the combustion was not efficient and burning more at the back of the engine.

How is your knock sensor?
whywoody
10-13-2009, 11:45 PM
I'll have to hook up my OTC4000e and try your method.
I have definately heard knock with no CEL flash,but so-far nothing has broken.I lift off the gas right away,but it's not a good method really.
The knock sensor isn't new,but it does trip the CEL at lower rpm/too much vac advance etc while cruising,or if the engine is too cold in the mornings and still a bit rattly.

Like Turbovanman is finding,my engine feels great with lots of vac advance,and also low boost part throttle advance.I'm playing with the timing tables alot,and don't feel too confident in what knock voltages are OK...