Speed Density Tuning
Joined: Nov 2001
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From: LT1 land...the "409" of the 90s!
Sorry Mark I did not get a thing done today save for letting my body rest 
I slept most of the day. I did not get home till 4:30Am this morning and between that and working seven days a week I was toast
I plan on doing some playing this week. I have some ideas..just never enough time
I have like 60 hours on this damn idles issue! Stupid LS1s Lt1s are easy LOL
I slept most of the day. I did not get home till 4:30Am this morning and between that and working seven days a week I was toast
I plan on doing some playing this week. I have some ideas..just never enough time
I have like 60 hours on this damn idles issue! Stupid LS1s
Lt1s are easy LOL 
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From: Marysville, WA
I started out by unplugging the IAC before I started the car. Ran fine! Idled about 1200rpm, but 0 surging. So, this is what I did & it idles better now than it has since the stall:
Before
RAF (Base Running Airflow)
18.1 15.75 13.6 12 10.6 7.69 6.2 6.2 6.2 6.2
IAC Park Position Airflow
33 28 23 21 19 14 10 8 8 8
Now
RAF
22.63 19.69 17 15 13.25 9.61 8.53 8.53 8.53 8.53
IAC
37.95 32.2 26.45 24.15 21.85 16.1 11.5 9.2 9.2 9.2
and I leaned out the Primary VE table in the 400-1200 rpm up thru the 55kpa cells x .80%
Now if I hold the rpms up at 2k+ for 20 sec & let off it surges slightly once & then regains idle. NO surging at startup....ZERO! COld, hot, nadd. The only problem is if I start it & pull it into gear immediately it dies. WHich is odd because it I let it sit for 30 sec A& then do it, the rpms don't even flutter.
Thoughts Ellis? Or anyone else....
Before
RAF (Base Running Airflow)
18.1 15.75 13.6 12 10.6 7.69 6.2 6.2 6.2 6.2
IAC Park Position Airflow
33 28 23 21 19 14 10 8 8 8
Now
RAF
22.63 19.69 17 15 13.25 9.61 8.53 8.53 8.53 8.53
IAC
37.95 32.2 26.45 24.15 21.85 16.1 11.5 9.2 9.2 9.2
and I leaned out the Primary VE table in the 400-1200 rpm up thru the 55kpa cells x .80%
Now if I hold the rpms up at 2k+ for 20 sec & let off it surges slightly once & then regains idle. NO surging at startup....ZERO! COld, hot, nadd. The only problem is if I start it & pull it into gear immediately it dies. WHich is odd because it I let it sit for 30 sec A& then do it, the rpms don't even flutter.
Thoughts Ellis? Or anyone else....
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From: Marysville, WA
I forgot to let it go thru it's idle relearn process, so when I cold started it again, it ran like crap. So I raised the idle up at cold tmeps a little & ran it for 5 min park, 5 in drive, and now it seems OK again. We'll see tomorrow how it runs. Bed time.....
Joined: Nov 2001
Posts: 10,023
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From: LT1 land...the "409" of the 90s!
I am working on it. I reset the Z today. I set the TB back to where it was and TPS reset to .60. Then an Idle relearn. She fired right off and completed the idle relearn with out issue. I let it sit for 30 minutes. I hit the key and it fired right off. It was smooth then hunted for the idle three or four times and settled in. so I yanked it into drive and all was well. I will try it again at ten and in the morning. It is almost out of gas so not to many test drives till pay day
Speaking of test drive I went for a short one and cruise was almost non-existant
If it stays where it is at i am happy. We will give yours a go then
Speaking of test drive I went for a short one and cruise was almost non-existant
If it stays where it is at i am happy. We will give yours a go then
Last edited by TwoFast4Lv; May 16, 2005 at 10:57 PM.
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From: Marysville, WA
yEAH, EVERY TIME i THINK i GOT IT, IT RUNS LIKE CRAP THE NEXT TIME OUT. i JUST REALISED i HAD UNDONE THE TIMING FIXES bILL & i MADE, SO i JUST BUMPED THE TIMING UP TO 30* IN ALL OF THE CELLS 400-1200 RPM UP TO 56G/SEC. aND IT RUNS BETTER....AGAIN. Argh, caps lock!!!!!!!!!!!!!
And now I have an oil leak. That must have been the puffs of smoke you saw Eric. Took me a while....now if only I can figure out where it's coming from.
And now I have an oil leak. That must have been the puffs of smoke you saw Eric. Took me a while....now if only I can figure out where it's coming from.
Joined: Nov 2001
Posts: 10,023
Likes: 6
From: LT1 land...the "409" of the 90s!
I also 'Think" I made progress today. I will relay what I told Mark.
What we are dealing with here is an un-known calculation that figures IAC position from Temp, Idle speed and Grams Per second. Seeing how we can not adjust it the best we can do is try to work with it in the relm we need. What I did was logg(manualy..AUTO TAP SUCKS!!!) what was going on. When ever I would get a hunting idle it could see the computer trying to force either a higher or lower IAC then the engine would idle with. I have been in the ball park for a while now so today I adjusted the idle to change or match the forced IAC position.
It looks like it will be fairly cold tonight so I will get a better idle in the morning if I am still in the ball park or need to lower the colder Idle numbers. Today dead cold it started right up and was fine till it hit a certian temp. I noticed this was where the idle dropped in the tables. Once fully warmed up it was fine again. If you let it cool into the temp area again it would not start and run with out several attempts and then hunt all over till it warmed up and settled in again.
Watching the scanner I could see the PCM trying to drop the IAC 20 counts when this would happen. that is what drew me to where i am at today.
Only time wil tell. as Mark has said many times. Every time we think we have this thing licked it takes off again!
Wish us luck! If it works Marks car is next!!
What we are dealing with here is an un-known calculation that figures IAC position from Temp, Idle speed and Grams Per second. Seeing how we can not adjust it the best we can do is try to work with it in the relm we need. What I did was logg(manualy..AUTO TAP SUCKS!!!) what was going on. When ever I would get a hunting idle it could see the computer trying to force either a higher or lower IAC then the engine would idle with. I have been in the ball park for a while now so today I adjusted the idle to change or match the forced IAC position.
It looks like it will be fairly cold tonight so I will get a better idle in the morning if I am still in the ball park or need to lower the colder Idle numbers. Today dead cold it started right up and was fine till it hit a certian temp. I noticed this was where the idle dropped in the tables. Once fully warmed up it was fine again. If you let it cool into the temp area again it would not start and run with out several attempts and then hunt all over till it warmed up and settled in again.
Watching the scanner I could see the PCM trying to drop the IAC 20 counts when this would happen. that is what drew me to where i am at today.
Only time wil tell. as Mark has said many times. Every time we think we have this thing licked it takes off again!
Wish us luck! If it works Marks car is next!!
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From: Marysville, WA
I tried teaking 1 parameter at a time, but so many of these affect or are affected by another param that I'm not sure that's the right approach. So I tried doing 2-3 of them at the same time that seem to be connected (according to write-ups) and it seemed to be working. But in the end it almost got to the point where it would run.
I think I am either going too big on my adjustments, or I'm missing something. I tweak one area & it gets better. But when I start it the next time, it runs worse than ever. So last night I gave up (again) and reloaded my tune from 4 weeks ago that we worked on after the Yank install.
**** on it. It runs good WOT. I'm going racing. (but I do need it to idle good by next month so I can go pass smog to get plates)
I think I am either going too big on my adjustments, or I'm missing something. I tweak one area & it gets better. But when I start it the next time, it runs worse than ever. So last night I gave up (again) and reloaded my tune from 4 weeks ago that we worked on after the Yank install.
**** on it. It runs good WOT. I'm going racing. (but I do need it to idle good by next month so I can go pass smog to get plates)
