• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Thinking of converting to E85.. Yes or Ne??



Im not second guessing anyone cus im unsure but im asking. Isnt that torque reduction during shift points in spark and fuel retard not timing? I thought kr was timing retard. Im lost on how that works exactly.
 
Ginseng said:
Im not second guessing anyone cus im unsure but im asking. Isnt that torque reduction during shift points in spark and fuel retard not timing? I thought kr was timing retard. Im lost on how that works exactly.
Click to expand...

KR is timing retard by the PCM from signals of detonation given by the knock sensors.


Sent from my iPhone using Tapatalk - now Free
 
Shayne, the way GM designed the pcm etc. They toss that amount say 2 degrees of retardation (removal of 2 degrees of timing) by injecting it as kr to decrease timing at the shift point in order to reduce power. As seen in the picture, it's dependent on the foot pounds of torque and the shift point.
 
Thanks crb but thats not quite what i meant.

Bill thats what i was looking for so basicly if im gradually accelerating the timing will be less adjusted during shift points by the pcm compared to if i was full throttle?
Does this apply to say going up hill or down hill in both equations? Cus i imagine more load= more torque needed going up hill= more retard? If this makes sense lol

Edit: What im getting at is i wont really see any kr when i first get my car to operating temp and start gunning around. When i have been driving the car awhile and my trans temp get up to say 180-200 i will start seeing knock. That knock will raise further when going up hill.
Is this due to the added friction in the trans from being so hot? Causing more load on the engine, and causing more torque needed from the engine because of?
 
Last edited:


hey crb, so you filled up with e85 and your car ran fine without having to make tuning adjustments? bc im gonna swap soon and was wondering how i could get 100% e85 by the time i get it tuned and have the fuel filter changed and ready to go.
 
TEK310 said:
hey crb, so you filled up with e85 and your car ran fine without having to make tuning adjustments? bc im gonna swap soon and was wondering how i could get 100% e85 by the time i get it tuned and have the fuel filter changed and ready to go.
Click to expand...

Correct.. Just fill her up and make sure you don't hit the skinny pedal too hard LOL. Naw, you'll be fine, just noooo boost until you tune!


Sent from my iPhone using Tapatalk - now Free
 


Sorry to bring up the whole timing debate again.... Iv been gone from the forums for a while and haven't had a chance to pipe in. One thing you guys have to remember is that I am running a high compression setup.... Higher compression = me hitting peak combustion in a shorter amount of time. I need less time before TDC to reach peak combustion. I rolled into the dyno session with a 3.8" pulley, 230whp, and 19* of timing. Left with 15* of timing, a 3.6" pulley, and 260 ish whp. On a low compression setup I have NO DOUBT WHATSOEVER that more timing would be very beneficial. Now on e85 you do get more headroom to add timing if you arent already at your maximum useful timing. So if you are still rocking stock timing by all means take advantage of the additional octaine and crank the timing up.
 
BillBoost37 said:
It's a shame your ego is larger than your base of knowledge


That's induced as KR BTW.
Click to expand...

There is no such thing as KR programmed by the PCM to reduce torque on shifts. The PCM retards timing independent of the knock detection system.
KR is a direct result of noise picked up by the knock sensors in a certain frequency range. There is only knock, and false knock... there is no "programmed knock" for torque management.
You don't have to agree with me, you can just be wrong.

The small blips that Chris is seeing (under 1*) are likely from noise being picked up somewhere else... not from actual knock/detonation.
The characteristics of real knock are opposite that of false knock.
 
I always thought the blip of KR I get at shift point here and there was false KR because sometimes it happens and sometimes not. It also occurs as the tranny shifts not pre shift. If the PCM was doing it wouldn't it happen every time I went wot? Not trying to contradict anyone's claims here, it is just what I've noticed with my own application.


Sent from my iPhone using Tapatalk
 
SnowFlake said:
You don't have to agree with me, you can just be wrong.
Click to expand...

LOL, I've admitted to being wrong etc many times. It's called being humble, when you learn it ... let us know. Til then you may want to consider browsing the FSM on the info you are speaking about. You can't find the term "False knock" in the manual, because false knock isn't a real item. It's a mechanical issue that needs to be fixed.
 


False knock is when the knock sensors pick up on a noise in the same frequency range as real knock, but knock never actually occurred.
It's my goal to ensure that people can find and read information that is both relevant to the topic and correct.
What you're propagating is irrelevant and false.

Chris, your car isn't "knocking" during the shift because of the torque management. I hope you understand this concept is ridiculous.
 
Again im just trying to understand this. The timing retard programmed in the pcm during shifts is torque management to save the trans life not to combat knock?. But does or doesnt show on a scan gauge as actually kr? If it did i imagine everyone would see kr during shifts but not everyone does. But i thought the scan gauges read timing retarded in degrees to combat knock. Now is kr on a gauge reading retard only during actually knock or false knock? or is it reading the actual knock or false knock thats accuring in degrees? Now its possible gm programmed that retard to combat knock that is more probable during shifts.

Edit: So if we took those values of what bill posted and set to zero would the car be more prone to knock or would it just put more stress on the tranny?
 
Last edited:
Ginseng said:
Again im just trying to understand this. The timing retard programmed in the pcm during shifts is torque management to save the trans life not to combat knock?. But does or doesnt show on a scan gauge as actually kr? If it did i imagine everyone would see kr during shifts but not everyone does. But i thought the scan gauges read timing retarded in degrees to combat knock. Now is kr on a gauge reading retard only during actually knock or false knock? or is it reading the actual knock or false knock thats accuring in degrees? Now its possible gm programmed that retard to combat knock that is more probable during shifts.

Edit: So if we took those values of what bill posted and set to zero would the car be more prone to knock or would it just put for stress on the tranny?
Click to expand...

What Bill is saying is confusing an issue that really isn't even an issue.
The torque management system is just that... torque management. It has nothing to do with knock.
KR is either knock, or something else making noise that falls within the frequency range of knock.

This is 3800 101 here.
I'm sorry you guys are being confused by Bill.

This is a decent write up that seems relevant.
http://www.zzperformance.com/blog/about-knock-retard-kr/
 
You must log in or register to reply here.
Back
Top