Aluminum Flywheel Changed Tuning?
Aluminum Flywheel Changed Tuning? I just installed a new clutch with aluminum flywheel and solid motor mounts. Before the install, I had typical big cam idle behavior: idled below commanded idle until warmed up.
Now it starts with a roar without even touching the gas, just like it did with the stock cam.
That's cool.
BUT, many times it does not come back down to the correct idle when coming to a stop. It can be anywhere form 1000 to 2500 rpm! EFILive reveals IAC counts staying high in these situations. When it comes down to 1000 rpm (the commanded idle speed) IAC is 30 like it's supposed to be.
Usually when the idle hangs, it's after I blipped the throttle. If it hangs, I can lightly touch the gas, and it comes back down! IAC counts do the same.
Can't find any hoses off or any sources of a vaccuum leak from the install. (I had the motor out of the car) Furthermore, if I unplug the IAC, the strange behavior goes away and it just acts like an LS1 with the IAC unplugged.
Anyone have any ideas? I hate to admit I'm stumped on this one.
Now it starts with a roar without even touching the gas, just like it did with the stock cam.
That's cool.BUT, many times it does not come back down to the correct idle when coming to a stop. It can be anywhere form 1000 to 2500 rpm! EFILive reveals IAC counts staying high in these situations. When it comes down to 1000 rpm (the commanded idle speed) IAC is 30 like it's supposed to be.
Usually when the idle hangs, it's after I blipped the throttle. If it hangs, I can lightly touch the gas, and it comes back down! IAC counts do the same.
Can't find any hoses off or any sources of a vaccuum leak from the install. (I had the motor out of the car) Furthermore, if I unplug the IAC, the strange behavior goes away and it just acts like an LS1 with the IAC unplugged.
Anyone have any ideas? I hate to admit I'm stumped on this one.
Last edited by Cal; May 27, 2005 at 05:08 PM.
move "IAC position vs. effective area" table to the right a few and lower the "Idle Airflow vs. ECT" table........
the computer thinks your engine needs more air than it really does (it over corrects).....the aluminum flywheel takes less HP to turn (less air/fuel) so a little over correction goes further.....
the computer thinks your engine needs more air than it really does (it over corrects).....the aluminum flywheel takes less HP to turn (less air/fuel) so a little over correction goes further.....
Thanks, I'm going to have a look at those tables. I don't remember seeing an "IAC position vs. effective area" table in LS1edit. Do I need HPtuners to access that one?
Originally Posted by Cal
Thanks, I'm going to have a look at those tables. I don't remember seeing an "IAC position vs. effective area" table in LS1edit. Do I need HPtuners to access that one?
hmmm.......I don't remember if LS1Edit had that table or not.........crap......
worst case you can still do the RAF (running airflow) table.........
FormerVendor
Joined: Jan 2003
Posts: 525
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From: Melbourne, Australia
HPTuners allows you to modify that table but i doubt it is your problem. That table just calibrates the IAC motor steps vs airflow and unless you have modded your IAC it should be left alone.
Your idle airflow is too high. This is where you need a good scanner (like ours) that lets you monitor the adaptive idle trims to see if they are reaching the adaptive limits and also see when they have relearned the new idle settings after you change the running airflow.
One way you can do it without knowing your idle trims is to log the "IAC Desired Airflow" and put those numbers in your base idle airflow table as the engine warms up. However, you will still not know if/when the adaptive trims have settled to reasonable and consistent values across various engine operation temps.
Cheers,
Chris...
HPTuners
Your idle airflow is too high. This is where you need a good scanner (like ours) that lets you monitor the adaptive idle trims to see if they are reaching the adaptive limits and also see when they have relearned the new idle settings after you change the running airflow.
One way you can do it without knowing your idle trims is to log the "IAC Desired Airflow" and put those numbers in your base idle airflow table as the engine warms up. However, you will still not know if/when the adaptive trims have settled to reasonable and consistent values across various engine operation temps.
Cheers,
Chris...
HPTuners
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FormerVendor
Joined: Jan 2003
Posts: 525
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From: Melbourne, Australia
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