Can someone who's tuned a BIG cam please post steps?
02-25-2005, 02:55 PM
#1
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Can someone who's tuned a BIG cam please post steps? I have it idling and running ok in gear, but have some stalling when there is a rapid transition from moderate throttle to 0 tps. I did this by adjusting my idle airflow (global +2) and idle rpm targets (900 for everything).
TIA
TIA
02-25-2005, 04:00 PM
#2
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Log your idle airflow when stable and set the idle airflow value
to just below what you observe. Was +2 enough to get you there?
Big cams want a lot of fiddling with the VE table (on a TRex I
found the "low end" was all the way up to about 2000RPM).
Here is the smoother VE table I stopped at (not to say it's
ideal, it was "good enough to quit messing"). I made a custom
"VE debug" tune for the guy and had him ride around collecting
O2 data over a couple of sessions with me updating the VE table
after each one, until it got to even keel.
Also idle may show very high fuel air multiplier in open loop that
wants the OLFA table massaged (if you see a commanded 1.4
(10:1 cold idle AFR) this is where it comes from). The rapid-drop
problem probably wants you to play with the throttle follower
decay to get a soft landing though the airflow if set close to
actual-idle airflow readings may be enough of a backstop.
Do you have a converter on that truck? Seems like the idle would
be kind of loaded up if it's a stock converter. I can't imagine running
that big a cam without one but see no indication in the sig, unless
that's the "PI 10.5" bit.
TRex primary VE table (for amusement purposes only, no warranty):
27 31 34 37 40 42 44 46 48 50 52 54 55 56 57 57 56 56 55 55
30 34 37 41 45 48 52 54 57 60 62 64 66 68 69 69 68 68 67 67
32 36 40 44 48 53 57 60 63 67 70 73 74 76 77 77 77 76 76 75
34 38 42 46 50 55 60 64 67 71 75 78 80 82 83 83 82 82 81 81
36 40 44 48 52 57 62 66 70 74 77 80 83 85 86 86 85 85 84 84
38 42 46 50 54 59 64 68 72 76 79 82 85 87 88 88 87 87 86 86
40 44 48 52 56 61 66 70 74 78 81 84 87 89 90 90 89 89 88 88
41 45 49 54 58 63 67 71 75 79 83 86 89 91 91 91 90 90 89 89
42 46 50 55 60 64 68 73 76 80 84 88 90 92 92 92 91 91 90 89
43 47 51 56 61 65 69 74 77 81 85 89 91 93 93 93 92 92 91 90
44 48 52 57 62 66 70 74 78 82 86 89 92 93 93 93 93 92 91 90
45 49 53 59 64 68 71 75 79 83 87 90 93 94 94 94 94 93 92 91
46 50 55 60 65 70 73 76 80 84 88 91 93 95 95 95 95 94 93 92
47 52 56 61 67 71 74 78 81 85 88 91 94 96 96 96 95 95 94 93
48 53 57 62 68 72 75 79 82 86 89 92 95 96 96 96 96 95 94 93
50 54 58 63 69 73 76 80 83 87 90 93 96 97 97 97 96 96 95 94
51 55 59 64 70 74 77 81 84 88 91 94 97 99 99 99 97 97 96 95
52 56 60 65 71 75 78 82 85 89 92 95 98 100 100 100 98 97 96 96
53 57 61 66 72 76 79 82 85 89 93 95 98 100 101 100 98 97 96 96
to just below what you observe. Was +2 enough to get you there?
Big cams want a lot of fiddling with the VE table (on a TRex I
found the "low end" was all the way up to about 2000RPM).
Here is the smoother VE table I stopped at (not to say it's
ideal, it was "good enough to quit messing"). I made a custom
"VE debug" tune for the guy and had him ride around collecting
O2 data over a couple of sessions with me updating the VE table
after each one, until it got to even keel.
Also idle may show very high fuel air multiplier in open loop that
wants the OLFA table massaged (if you see a commanded 1.4
(10:1 cold idle AFR) this is where it comes from). The rapid-drop
problem probably wants you to play with the throttle follower
decay to get a soft landing though the airflow if set close to
actual-idle airflow readings may be enough of a backstop.
Do you have a converter on that truck? Seems like the idle would
be kind of loaded up if it's a stock converter. I can't imagine running
that big a cam without one but see no indication in the sig, unless
that's the "PI 10.5" bit.
TRex primary VE table (for amusement purposes only, no warranty):
27 31 34 37 40 42 44 46 48 50 52 54 55 56 57 57 56 56 55 55
30 34 37 41 45 48 52 54 57 60 62 64 66 68 69 69 68 68 67 67
32 36 40 44 48 53 57 60 63 67 70 73 74 76 77 77 77 76 76 75
34 38 42 46 50 55 60 64 67 71 75 78 80 82 83 83 82 82 81 81
36 40 44 48 52 57 62 66 70 74 77 80 83 85 86 86 85 85 84 84
38 42 46 50 54 59 64 68 72 76 79 82 85 87 88 88 87 87 86 86
40 44 48 52 56 61 66 70 74 78 81 84 87 89 90 90 89 89 88 88
41 45 49 54 58 63 67 71 75 79 83 86 89 91 91 91 90 90 89 89
42 46 50 55 60 64 68 73 76 80 84 88 90 92 92 92 91 91 90 89
43 47 51 56 61 65 69 74 77 81 85 89 91 93 93 93 92 92 91 90
44 48 52 57 62 66 70 74 78 82 86 89 92 93 93 93 93 92 91 90
45 49 53 59 64 68 71 75 79 83 87 90 93 94 94 94 94 93 92 91
46 50 55 60 65 70 73 76 80 84 88 91 93 95 95 95 95 94 93 92
47 52 56 61 67 71 74 78 81 85 88 91 94 96 96 96 95 95 94 93
48 53 57 62 68 72 75 79 82 86 89 92 95 96 96 96 96 95 94 93
50 54 58 63 69 73 76 80 83 87 90 93 96 97 97 97 96 96 95 94
51 55 59 64 70 74 77 81 84 88 91 94 97 99 99 99 97 97 96 95
52 56 60 65 71 75 78 82 85 89 92 95 98 100 100 100 98 97 96 96
53 57 61 66 72 76 79 82 85 89 93 95 98 100 101 100 98 97 96 96
02-27-2005, 08:21 PM
#4
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Hey Jimmy,
The follower and a little megasquirt decell fuel enrichment did the trick on the stalling -- except when cold. Can you offer any advice for getting cold idle to work as well as warm idle?
Also, I asked this on the hpt site, but what would you consider ground clutter for the 0300 code? I'm seeing in the 70ish intermittently on #4 (which was fouled when I changed the plugs).
The follower and a little megasquirt decell fuel enrichment did the trick on the stalling -- except when cold. Can you offer any advice for getting cold idle to work as well as warm idle?
Also, I asked this on the hpt site, but what would you consider ground clutter for the 0300 code? I'm seeing in the 70ish intermittently on #4 (which was fouled when I changed the plugs).
02-27-2005, 10:37 PM
#5
Originally Posted by jimmyblue
Log your idle airflow when stable and set the idle airflow value
to just below what you observe. Was +2 enough to get you there?
Big cams want a lot of fiddling with the VE table (on a TRex I
found the "low end" was all the way up to about 2000RPM).
Here is the smoother VE table I stopped at (not to say it's
ideal, it was "good enough to quit messing"). I made a custom
"VE debug" tune for the guy and had him ride around collecting
O2 data over a couple of sessions with me updating the VE table
after each one, until it got to even keel.
Also idle may show very high fuel air multiplier in open loop that
wants the OLFA table massaged (if you see a commanded 1.4
(10:1 cold idle AFR) this is where it comes from). The rapid-drop
problem probably wants you to play with the throttle follower
decay to get a soft landing though the airflow if set close to
actual-idle airflow readings may be enough of a backstop.
Do you have a converter on that truck? Seems like the idle would
be kind of loaded up if it's a stock converter. I can't imagine running
that big a cam without one but see no indication in the sig, unless
that's the "PI 10.5" bit.
TRex primary VE table (for amusement purposes only, no warranty):
27 31 34 37 40 42 44 46 48 50 52 54 55 56 57 57 56 56 55 55
30 34 37 41 45 48 52 54 57 60 62 64 66 68 69 69 68 68 67 67
32 36 40 44 48 53 57 60 63 67 70 73 74 76 77 77 77 76 76 75
34 38 42 46 50 55 60 64 67 71 75 78 80 82 83 83 82 82 81 81
36 40 44 48 52 57 62 66 70 74 77 80 83 85 86 86 85 85 84 84
38 42 46 50 54 59 64 68 72 76 79 82 85 87 88 88 87 87 86 86
40 44 48 52 56 61 66 70 74 78 81 84 87 89 90 90 89 89 88 88
41 45 49 54 58 63 67 71 75 79 83 86 89 91 91 91 90 90 89 89
42 46 50 55 60 64 68 73 76 80 84 88 90 92 92 92 91 91 90 89
43 47 51 56 61 65 69 74 77 81 85 89 91 93 93 93 92 92 91 90
44 48 52 57 62 66 70 74 78 82 86 89 92 93 93 93 93 92 91 90
45 49 53 59 64 68 71 75 79 83 87 90 93 94 94 94 94 93 92 91
46 50 55 60 65 70 73 76 80 84 88 91 93 95 95 95 95 94 93 92
47 52 56 61 67 71 74 78 81 85 88 91 94 96 96 96 95 95 94 93
48 53 57 62 68 72 75 79 82 86 89 92 95 96 96 96 96 95 94 93
50 54 58 63 69 73 76 80 83 87 90 93 96 97 97 97 96 96 95 94
51 55 59 64 70 74 77 81 84 88 91 94 97 99 99 99 97 97 96 95
52 56 60 65 71 75 78 82 85 89 92 95 98 100 100 100 98 97 96 96
53 57 61 66 72 76 79 82 85 89 93 95 98 100 101 100 98 97 96 96
to just below what you observe. Was +2 enough to get you there?
Big cams want a lot of fiddling with the VE table (on a TRex I
found the "low end" was all the way up to about 2000RPM).
Here is the smoother VE table I stopped at (not to say it's
ideal, it was "good enough to quit messing"). I made a custom
"VE debug" tune for the guy and had him ride around collecting
O2 data over a couple of sessions with me updating the VE table
after each one, until it got to even keel.
Also idle may show very high fuel air multiplier in open loop that
wants the OLFA table massaged (if you see a commanded 1.4
(10:1 cold idle AFR) this is where it comes from). The rapid-drop
problem probably wants you to play with the throttle follower
decay to get a soft landing though the airflow if set close to
actual-idle airflow readings may be enough of a backstop.
Do you have a converter on that truck? Seems like the idle would
be kind of loaded up if it's a stock converter. I can't imagine running
that big a cam without one but see no indication in the sig, unless
that's the "PI 10.5" bit.
TRex primary VE table (for amusement purposes only, no warranty):
27 31 34 37 40 42 44 46 48 50 52 54 55 56 57 57 56 56 55 55
30 34 37 41 45 48 52 54 57 60 62 64 66 68 69 69 68 68 67 67
32 36 40 44 48 53 57 60 63 67 70 73 74 76 77 77 77 76 76 75
34 38 42 46 50 55 60 64 67 71 75 78 80 82 83 83 82 82 81 81
36 40 44 48 52 57 62 66 70 74 77 80 83 85 86 86 85 85 84 84
38 42 46 50 54 59 64 68 72 76 79 82 85 87 88 88 87 87 86 86
40 44 48 52 56 61 66 70 74 78 81 84 87 89 90 90 89 89 88 88
41 45 49 54 58 63 67 71 75 79 83 86 89 91 91 91 90 90 89 89
42 46 50 55 60 64 68 73 76 80 84 88 90 92 92 92 91 91 90 89
43 47 51 56 61 65 69 74 77 81 85 89 91 93 93 93 92 92 91 90
44 48 52 57 62 66 70 74 78 82 86 89 92 93 93 93 93 92 91 90
45 49 53 59 64 68 71 75 79 83 87 90 93 94 94 94 94 93 92 91
46 50 55 60 65 70 73 76 80 84 88 91 93 95 95 95 95 94 93 92
47 52 56 61 67 71 74 78 81 85 88 91 94 96 96 96 95 95 94 93
48 53 57 62 68 72 75 79 82 86 89 92 95 96 96 96 96 95 94 93
50 54 58 63 69 73 76 80 83 87 90 93 96 97 97 97 96 96 95 94
51 55 59 64 70 74 77 81 84 88 91 94 97 99 99 99 97 97 96 95
52 56 60 65 71 75 78 82 85 89 92 95 98 100 100 100 98 97 96 96
53 57 61 66 72 76 79 82 85 89 93 95 98 100 101 100 98 97 96 96
02-27-2005, 10:49 PM
#6
TECH Senior Member
Originally Posted by Cal
Jimmy, those VE numbers are all a factor of ten lower than I would expect . . . is that because I'm using LS1edit and you're using something else?
Those values are a percent of the theoretical maximum amount of air in a cylinder under non boost situations... (in HPT I believe it was meant to put the values in a factor that people can understand... efficiency is a percent of the max ... not the amount of grams)
I'm not sure of the formulas off hand for determining max amount of air given a cylindrical volume... if no one replies I'll look it up tomorrow....
those % are based on a stock bore and stroke LS1 also ...
02-27-2005, 11:03 PM
#7
Oh OK, thanks horist. I didn't realize HPT did it that way. I believe the volume of a cylinder is
Volume = pi * r**2 * h , then applying the density of air I should be able to get it. But if you have a "canned" formula, at least I could check my work.
Volume = pi * r**2 * h , then applying the density of air I should be able to get it. But if you have a "canned" formula, at least I could check my work.
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03-01-2005, 04:28 PM
#8
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Erik, be sure that the rapid TPS movements of the drive-by-wire throttle body aren't causing your megasquirt to go into acell enrichment.
Jim had that issue at idle as well, it would flood the motor.
Run a datalog and send it to me, I think you just need to play with warmup enrichments a little more also.
-scott
Jim had that issue at idle as well, it would flood the motor.
Run a datalog and send it to me, I think you just need to play with warmup enrichments a little more also.
-scott