knock retard and timing question
04-18-2002, 09:02 PM
#1
knock retard and timing question my atap logs show about 10-15deg of timing at wot. sometimes there is a little KR, 2deg and that quickly tapers sown to 0deg. the KR seems ok, 2 deg isn't much but the timing only being 10-15deg seems kind of low.
what can cause this? others in the truck forum report 20deg plus on their NA trucks, does the computer learn that the engine will knock with a certain amount of timing and just stop asking for it after awhile? or should it ask for a set amount and let the KR pull timing?
the best gas i can get is 92, the truck runs way worse on 91 so mabey 92 isn't good enuff, i haven't tried anything better yet.
what can cause this? others in the truck forum report 20deg plus on their NA trucks, does the computer learn that the engine will knock with a certain amount of timing and just stop asking for it after awhile? or should it ask for a set amount and let the KR pull timing?
the best gas i can get is 92, the truck runs way worse on 91 so mabey 92 isn't good enuff, i haven't tried anything better yet.
04-20-2002, 12:31 AM
#2
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Re: knock retard and timing question It all depends on where you are getting your KR. Log your MAF flow, KR, RPMs, and timing. Your PCM has set parameters for timing. With the Whipple, I bet you extending into an area of your timing table that has a low timing value to begin with. Timing is given out by MAF and RPMs.
Be happy you don't have more KR than you are showing. I have it all over the place.
Be happy you don't have more KR than you are showing. I have it all over the place.
04-21-2002, 06:36 AM
#3
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Re: knock retard and timing question DO you have programming with your whipple?
My program takes out timing so that I make between 19 and 21 degrees timing advance during WOT.
N/A this would not be good. But with FI, it is sometimes neccesary to prevent detonation. The power is still there because of the Supercharger, so the reduction in timing is no biggy.
If the timing is doing that on it's own without programming, though, I'd be concerned and want to know why.
Hope that helps. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
My program takes out timing so that I make between 19 and 21 degrees timing advance during WOT.
N/A this would not be good. But with FI, it is sometimes neccesary to prevent detonation. The power is still there because of the Supercharger, so the reduction in timing is no biggy.
If the timing is doing that on it's own without programming, though, I'd be concerned and want to know why.
Hope that helps. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
04-21-2002, 09:15 PM
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Re: knock retard and timing question I told you what I thought, but you didn't respond. Also, how is the whipple computer going to pull the bypass valve when the computer has no connectivity at all to the compressor? Did you do your own whipple install?
04-21-2002, 09:52 PM
#5
Re: knock retard and timing question take it easy big tex, i am kind of simple minded and trying to figure some of this out. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
i think your explanation seems the most likely, that i am geting into part of a table with my MAF that just has less timing programed but i would like to know if there is someone that knows for sure. i have loged those things that you said to, the knock retard kicks in right after i floor it but goes away quickly, the timeing jumps around between 10-15deg the whole run except for shifts where it drops to -10 or so.
the ecm has no conections to the bypass valve but the piggy back computer that came with the whipple does. the whipple computer monitors a few of the factory sensors and then decides how much fuel to add with it's 2 extra injectors and can go into a safety mode and pull the bypass valve if it see's a lean condition.
i did the install myself and from the conections i made between the whipple computer and the stock ECM i cant see any way the whipple computer can pull out timing, it looks to me like the whipple computer just monitors a few of the factory sensors but doesn't actualy comunicate with the ECM.
the whipple computer monitors both o'2s, IAT, TPS,MAP,MAF, crank shaft position sensor and engine coolant sensor, there are no other conections to the stock ECM. all of these conections are just t-taped joints, none of the factory wires were routed thru the whipple computer so there isnt any manipulation of the sensor readings going on.
i think your explanation seems the most likely, that i am geting into part of a table with my MAF that just has less timing programed but i would like to know if there is someone that knows for sure. i have loged those things that you said to, the knock retard kicks in right after i floor it but goes away quickly, the timeing jumps around between 10-15deg the whole run except for shifts where it drops to -10 or so.
the ecm has no conections to the bypass valve but the piggy back computer that came with the whipple does. the whipple computer monitors a few of the factory sensors and then decides how much fuel to add with it's 2 extra injectors and can go into a safety mode and pull the bypass valve if it see's a lean condition.
i did the install myself and from the conections i made between the whipple computer and the stock ECM i cant see any way the whipple computer can pull out timing, it looks to me like the whipple computer just monitors a few of the factory sensors but doesn't actualy comunicate with the ECM.
the whipple computer monitors both o'2s, IAT, TPS,MAP,MAF, crank shaft position sensor and engine coolant sensor, there are no other conections to the stock ECM. all of these conections are just t-taped joints, none of the factory wires were routed thru the whipple computer so there isnt any manipulation of the sensor readings going on.
04-22-2002, 12:14 AM
#6
Re: knock retard and timing question no programing, the whipple comes with a piggy back computer that controls 2 extra injectors, it also montors for a lean condition and can pull the bypass valve to prevent engine damage. as far as i can tell the stock computer is unchanged.
soo one of two things seem to be going on here, either the engine has been detecting knock and has decided to stop asking for full timing or the the extra air is pushing the MAF or MAP or some sensor into a part of the timing curve with less advance. i am sure someone in here will know what is going on.
soo one of two things seem to be going on here, either the engine has been detecting knock and has decided to stop asking for full timing or the the extra air is pushing the MAF or MAP or some sensor into a part of the timing curve with less advance. i am sure someone in here will know what is going on.
04-22-2002, 04:10 PM
#7
Re: knock retard and timing question if thats the case then i am probably geting all the timing my computer wants to give it, sounds like it is time for ls1edit! if i am not geting any KR and am geting all or nearly all of the timing that the computer alows then it sounds like better gas wont help any.
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04-23-2002, 12:36 AM
#8
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Re: knock retard and timing question Parish, you are gonna have to trust me on this one. I know the answer and can help if you want. Email me an autotap log w/ RPMs, MAF, timing, knock, and throttle Position. I will tell you what your MAX timing is.
Autotap is a slug, so numbers are a little off, but here is whay my truck shows: At 5200 RPMs, my stock PCM shows 12 deg timing MAX for my MAF flow of 43.
Richard
Autotap is a slug, so numbers are a little off, but here is whay my truck shows: At 5200 RPMs, my stock PCM shows 12 deg timing MAX for my MAF flow of 43.
Richard
