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Idle prob with a 98

This is a discussion on Idle prob with a 98 within the Computer & Tuning forums, part of the LSx Technical Help Section category; Heres the prob, I got a 98 LS1 with main mods being LT's, LS6 intake, 80mm TB, p&p descreened MAF, ...

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    Simpsons Did it!! 98formy's Avatar
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    Idle prob with a 98

    Heres the prob, I got a 98 LS1 with main mods being LT's, LS6 intake, 80mm TB, p&p descreened MAF, 224/224 .563/.563 114Lsa cam. On a cold start or if its been sitting too long, it just wont start by itself. To get it to start, I just give it a little gas and it starts rough, clears out after a few seconds, then it idles fine. My tuner just cant get it right for some reason. In order to get it to start on its own, the TPS needs to be at 1.2% open, but when its that high, the idle starts hunting when warm. One person says to try and slot the TPS holes to roll it back to zero and try it. What do you think of that or any other suggestions would be nice. I do got a 3/16 hole in the TB also.

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    TunedbyFrost.com Tuner Frost's Avatar
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    if your IAC counts are not in the 40-65 range at a hot idle with the throttle blade open as far as it will go (while still resetting to 0% TPS) then you must drill the blade to get the airflow.

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    Member cailey37's Avatar
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    The 98 ECM's are a bit#$ to get right! They changed them in 99 and gave people better tunablility......They can be tuned but I wouldn't go and drill a hole in the blade just yet....it just sounds like your tuner has missed something.......

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    Veteran 0rion's Avatar
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    I'm by far no expert but had these same problems and tried a bunch of different stuff before getting it figured out. I didn't drill the blade but flipped the set screw and opened the blade up using that because it's easily reversible.
    If I remember correctly most of my problems were solved with the IAC Park Position Airflow table. This is assuming he has your base air set. Base air in the lower temp's was my initial problem.

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    TunedbyFrost.com Tuner Frost's Avatar
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    The IAC counts must be gotten to a workable range as listed above before tuning idle, or you will be re-doing it after you fix your offset.

    HOWEVER... if you get a good idle once it's warm, and it's just a startup issue, have him look at the startup airflow tables and their decay rates. You can add airflow in the startup table or the friction startup table. Increase ALL values by the same percent while working to get good startup at the current temperature. Increase delays at startup to 16-22 cam revolutions. Set standard startup airflow decay to 0.600-0.800 or to taste.

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    Desired airflow table helps with idle issues add % to it both in gear and in P/N

    Put the stock screened MAF back in !!!!

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by tblu92 View Post
    Desired airflow table helps with idle issues add % to it both in gear and in P/N

    Put the stock screened MAF back in !!!!
    you can't set running airflow unless your counts are in range. I mean you can... but it won't be right. You need to log and see what it needs rather than just adding. There is a method to this. Also, he said the car was already tuned, in which case, adding a screened MAF will affect his AFR EVERYWHERE.

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    Quote Originally Posted by Frost View Post
    you can't set running airflow unless your counts are in range. I mean you can... but it won't be right. You need to log and see what it needs rather than just adding. There is a method to this. Also, he said the car was already tuned, in which case, adding a screened MAF will affect his AFR EVERYWHERE.
    Who says you can't set it that way You ?? who cares what the IAC counts are --all you want to is get the thing to idle--there is no law or IAC police I've been fixing idle problems on cammed cars that way for years--It won't be right? according to who ?? Such a ridiculous statement
    And--How do you know the MAF was tuned ? I was making a broad statement that 95% of all people already know that ported MAF's and de-screened MAF's suck--they are the culprit of most all fueling problems-How can you assume to know so much about what was done and what wasn't done to this car ?? YOU don't !!!--all you do is make yourself seem arrogant and foolish--Find out facts before your critisize again--just because he said the car was tuned doen't mean the MAF was calibrated --You just don't know-the poor man is looking for help--I was offering suggestions---but all you want to do is shoot yotr mouth off--i know your type--O-- B--- every minute--

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    Veteran 0rion's Avatar
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    Let's keep it civil guys. The guy is just looking for some suggestions.

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by tblu92 View Post
    Who says you can't set it that way You ?? who cares what the IAC counts are --all you want to is get the thing to idle--there is no law or IAC police I've been fixing idle problems on cammed cars that way for years--It won't be right? according to who ?? Such a ridiculous statement
    And--How do you know the MAF was tuned ? I was making a broad statement that 95% of all people already know that ported MAF's and de-screened MAF's suck--they are the culprit of most all fueling problems-How can you assume to know so much about what was done and what wasn't done to this car ?? YOU don't !!!--all you do is make yourself seem arrogant and foolish--Find out facts before your critisize again--just because he said the car was tuned doen't mean the MAF was calibrated --You just don't know-the poor man is looking for help--I was offering suggestions---but all you want to do is shoot yotr mouth off--i know your type--O-- B--- every minute--
    Tuners like you keep me in business.... Who says you can't set it that way? ...well you can set it that way, but what we like to call the RIGHT WAY is to log desired airflow and set the table for what the car is asking for rather than just sticking a number into the idle airflow tables. You can make them idle by throwing in a number TODAY, but as things change (ECT, outside temp, etc) you will have fluctuations.

    Ported and descreened MAFs tune no differently than stock MAFs, so unless you don't know what you are doing, it's a normal thing. Your comments lead me to believe you are one of the old-school tuners that thinks PE tuning yields consistent results rather than REALLY tuning airflow models so that you reach what you command. He said his car was tuned already and that the MAF was there. If you bring me a car it leaves tuned for the MAF and intake setup that is on the car; that's how it is and how it should be.

    I'm not the one exploding pissed off and looking "arrogant and foolish", Iquite the contrary. The car will TELL you what to use for RAF, you don't tell it, unless you want it to be wrong. Your IAC comments, MAF comments, and idle-air comments indicate that you do not, in fact, have a good grasp on what you are doing. It is not rooted in either science or solid theory & testing. I have seen you arguing until you get yourself worked up with Ed over another issue that you were wrong about, so I don't expect it to stop here.

    I am not the IAC police. Anyone who does this with any degree of success will tell you the same things about the counts. They MUST be in the proper range BEFORE idle tuning... Hello they affect base airflow!

    I am keeping this civil and hope this thread does not get locked or disappear.

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    Junior Member edcmat-l1's Avatar
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    Quote Originally Posted by tblu92 View Post
    Who says you can't set it that way You ?? who cares what the IAC counts are --all you want to is get the thing to idle--there is no law or IAC police I've been fixing idle problems on cammed cars that way for years--It won't be right? according to who ?? Such a ridiculous statement
    And--How do you know the MAF was tuned ? I was making a broad statement that 95% of all people already know that ported MAF's and de-screened MAF's suck--they are the culprit of most all fueling problems-How can you assume to know so much about what was done and what wasn't done to this car ?? YOU don't !!!--all you do is make yourself seem arrogant and foolish--Find out facts before your critisize again--just because he said the car was tuned doen't mean the MAF was calibrated --You just don't know-the poor man is looking for help--I was offering suggestions---but all you want to do is shoot yotr mouth off--i know your type--O-- B--- every minute--
    There he goes again->
    The phantom "tuner".......Kinda hot headed aint ya tbu?

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    Junior Member edcmat-l1's Avatar
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    Quote Originally Posted by Frost View Post
    Tuners like you keep me in business.... Who says you can't set it that way? ...well you can set it that way, but what we like to call the RIGHT WAY is to log desired airflow and set the table for what the car is asking for rather than just sticking a number into the idle airflow tables. You can make them idle by throwing in a number TODAY, but as things change (ECT, outside temp, etc) you will have fluctuations.

    Ported and descreened MAFs tune no differently than stock MAFs, so unless you don't know what you are doing, it's a normal thing. Your comments lead me to believe you are one of the old-school tuners that thinks PE tuning yields consistent results rather than REALLY tuning airflow models so that you reach what you command. He said his car was tuned already and that the MAF was there. If you bring me a car it leaves tuned for the MAF and intake setup that is on the car; that's how it is and how it should be.

    I'm not the one exploding pissed off and looking "arrogant and foolish", Iquite the contrary. The car will TELL you what to use for RAF, you don't tell it, unless you want it to be wrong. Your IAC comments, MAF comments, and idle-air comments indicate that you do not, in fact, have a good grasp on what you are doing. It is not rooted in either science or solid theory & testing. I have seen you arguing until you get yourself worked up with Ed over another issue that you were wrong about, so I don't expect it to stop here.

    I am not the IAC police. Anyone who does this with any degree of success will tell you the same things about the counts. They MUST be in the proper range BEFORE idle tuning... Hello they affect base airflow!

    I am keeping this civil and hope this thread does not get locked or disappear.

  13. #13
    Junior Member edcmat-l1's Avatar
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    On the technical side of all this, I have seen cars/tunes, that merely needed the open loop fueling, or the idle portion of the VE, or both, leaned out to get a good warm start with no pedal.
    It sounds to me like its "loading up", which would indicate to me it has too much fuel. Typical of a tune thats off, or a "maf" tune.
    As for the RAF, Frost has it right. Scan, log RAF numbers, and plug em in.
    As for descreened MAFs, The Z06s are descreened. I've descreened countless one. GM isnt having any problems. I dont have any problems. I cant say it make a big difference. But, I damn sure cant say it causes a bunch of problems either.

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    Simpsons Did it!! 98formy's Avatar
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    **UPDATE**

    The tuner had to pull 50% fuel and add 60% air flow to get it to ALMOST start on its own when cold. He took it to another shop for a second opinion and neither of them can get it figured out. The consensus is that something mechanical is affecting it, but all the sensors are in range. Does anyone here have any idea on where to start trying to determine the prob. Thanks guys

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    Junior Member edcmat-l1's Avatar
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    Quote Originally Posted by 98formy View Post
    **UPDATE**

    The tuner had to pull 50% fuel and add 60% air flow to get it to ALMOST start on its own when cold. He took it to another shop for a second opinion and neither of them can get it figured out. The consensus is that something mechanical is affecting it, but all the sensors are in range. Does anyone here have any idea on where to start trying to determine the prob. Thanks guys
    See if you cant get your tuner to post the tune on here or on one of the tuning forums, and then link back to here. That thing should be a big deal to get right. Thats a pretty mild cam.

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    Veteran 0rion's Avatar
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    what's he using to tune with hptuners? Try to get an idle log and post it up here or at hptuners site. I'm curious myself to see what your base air looks like. I probably can't fix it although some of these guys here probably can. I'd still like to see what it looks like.

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