Anyone wanna help with surging Files included

I havent seen what the idle air hole looks like on that throttle body, but to fix that problem on a bbk or simular, you need to make that hole going to the iac motor larger to allow it to flow more air when the motor needs it. Then to allow the car to learn its idle better, In asa we turned up the long term idle trims way up to 8.
your stock one is set to .5 max, and the min is -3.00 Changing that limit to be larger allows for the Car to learn its idle to be what it needs for you..

It works well on large cams as well as cams with less that 110 ls...
THere are tables for both park and drive. So all would need set..
All we have to do is give the computer more permission to do what it wants, and it does a good job.. Also, if you are having a surging problem at cruising, you may want to back off all your throttle follower table to 0 and watch the problem go away, If the throttle follower table is higher than the iac can produce it will make it do that also.

Dirk,

At idle, the RPM's are all over the place, also look what that is doing to the timing, it jumps from 24 that you have set in {B5915} to 30 or so.
I 'personally' would lower your min timing table {B5915} down to 10 or so.
Granted, this timing isn't going to cause your problem all by itself but you need to eliminate the spark influence on idle too until you get the rest sorted. For now zero out {B5935} and {B5936}.

Also, I noticed table {B4403} has had some major changes, I messed with this myself, and 'small' amounts made a big difference.
Can I ask why the big change?, have you tried restoring that to standard?.
I am pretty sure the result of having the table as you do will mean the IAC will not move far enough to correct over/under idle speeds.
Look at the steps at about 550RPM, you only have 36, then at 1300RPM you have 13 or so, it's basically doing nothing really.
I think all the surging etc is probably the mixtures causing it, but only because the IAC appears to have no control.

To set my IAC up this is what I did (non ETC).
Connect to PCM and command the IAC to 0 steps, go out and unplug the IAC.
Now mess with the IAC screw to get the thing to at least idle (you usually need to hold your foot down to get it started then ease off).
'If' you can get the car to idle without the IAC then you are pretty much there.
I aimed to get the engine to Idle (without the IAC) about 100 RPM below my desired Idle RPM.
That way, the IAC and spark should easily catch a stall before it happens.
Then, reconnect the IAC and see what happens.

Cheers,
Ross

Quote:

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Originally Posted by GMPX

Dirk,

At idle, the RPM's are all over the place, also look what that is doing to the timing, it jumps from 24 that you have set in {B5915} to 30 or so.
I 'personally' would lower your min timing table {B5915} down to 10 or so.
Granted, this timing isn't going to cause your problem all by itself but you need to eliminate the spark influence on idle too until you get the rest sorted. For now zero out {B5935} and {B5936}.

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Done

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Also, I noticed table {B4403} has had some major changes, I messed with this myself, and 'small' amounts made a big difference.
Can I ask why the big change?, have you tried restoring that to standard?.I am pretty sure the result of having the table as you do will mean the IAC will not move far enough to correct over/under idle speeds.
Look at the steps at about 550RPM, you only have 36, then at 1300RPM you have 13 or so, it's basically doing nothing really.
I think all the surging etc is probably the mixtures causing it, but only because the IAC appears to have no control.

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I just shifted the cells down to see if it would help per recommedation on ls1tech about this table and bigger TB's. It is now back to stock... For a 90 MM tb do you have any suggestions

Quote:

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To set my IAC up this is what I did (non ETC).
Connect to PCM and command the IAC to 0 steps, go out and unplug the IAC.
Now mess with the IAC screw to get the thing to at least idle (you usually need to hold your foot down to get it started then ease off).
'If' you can get the car to idle without the IAC then you are pretty much there.
I aimed to get the engine to Idle (without the IAC) about 100 RPM below my desired Idle RPM.
That way, the IAC and spark should easily catch a stall before it happens.
Then, reconnect the IAC and see what happens.

Cheers,
Ross

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Thanks I will give this a try today if the rain holds out.


wait4me I wasnt aware you could move the lern limits to 8 i will give that a try. THanks

Quote:

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LABELS Selection
Parameters Value
Max Speed for Idle Mode 0.000000 MPH
Max Throttle for Idle Mode 0.000000 %
Default IAC Motor Park Position 310.000000 steps
Maximum IAC Steps 365.000000 steps
Throttle Cracker enable speed 1.000000 MPH
Throttle Cracker disable speed 2.000000 MPH
Throttle Follower TPS change 0.996094 %
Idle Learn Enable Temp 176.000000 F
Idle Learn Disable Temp 233.585938 F
Idle Learn P/N Limit High 8.000000 Grams/Second
Idle Learn P/N Limit Low -8.000000 Grams/Second
Idle Learn P/N A/C On Limit High 8.000000 Grams/Second
Idle Learn P/N A/C On Limit Low -8.000000 Grams/Second
Idle Learn Drive Limit High 8.000000 Grams/Second
Idle Learn Drive Limit Low -8.000000 Grams/Second
Idle Learn Drive A/C On Limit High 8.000000 Grams/Second
Idle Learn Drive A/C On Limit Low -8.000000 Grams/Second
Fan #1 IAC Correction 0.150391 Grams/Second
Fan #2 IAC Correction 0.370117 Grams/Second
Max Idle RPM in Gear 1200.000000 RPM
Max Idle RPM in P/N 0.000000 RPM

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Hows that look

Yah, then you can set up the computer to be closer to what it needs also alot faster if you see where it takes you too from the 8, then you can adjust the table called idle adaptive airflow max stratigy verse engine coolant temp. You move it up or down depending on your needs to let it start out closer to what it wants. You know if the table needs adjusted because it will idle ruff or crappy at first, and then gets better as time goes on..

Quote:

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Originally Posted by wait4me

Yah, then you can set up the computer to be closer to what it needs also alot faster if you see where it takes you too from the 8, then you can adjust the table called idle adaptive airflow max stratigy verse engine coolant temp. You move it up or down depending on your needs to let it start out closer to what it wants. You know if the table needs adjusted because it will idle ruff or crappy at first, and then gets better as time goes on..

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That must not be in the pre release 7.1.9 version ;)

Ok i unplugged the IAC motor after setting it to 0 and after cracking the tb to about 13% the car stayed on and idles but still hunted. I started adding timing and got all teh way to 34* at idle before the car would stabilize and even then it hunted just a little. I added another .1 of a gm to the raf table to see if that will help but need to let the laptop recharge in order to log and use bidi controls


Isnt 35* kinda high. To me this sounds like Gen 1 SB territory

As a last ditch effort i am gonna re-flash my full calibration to an 01 and start from scratch

seems lkike a full reflash to a stock cal has cured my ailments. i need more testing to be sure though

Quote:

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Originally Posted by Dirk Diggler

Quote:

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Originally Posted by wait4me

Yah, then you can set up the computer to be closer to what it needs also alot faster if you see where it takes you too from the 8, then you can adjust the table called idle adaptive airflow max stratigy verse engine coolant temp. You move it up or down depending on your needs to let it start out closer to what it wants. You know if the table needs adjusted because it will idle ruff or crappy at first, and then gets better as time goes on..

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That must not be in the pre release 7.1.9 version ;)

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It's not in 'my' version either :shock: