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View Full Version : Lightweight clutch assembly flywheels alters tune



robz
January 6th, 2008, 09:20 AM
After installing an extremely lightweight clutch assembly I've noticed the car hunts for idle now.
This occurs at a stop and when putting it into neutral when the car is rolling at say 40 mph. It want to kick out and will stall.

Can some give me direction on what will be need to correct this in the tune. Thanks

TAQuickness
January 6th, 2008, 10:31 AM
You may need to adjust your throtle cracker and follower air flow values a bit, but most likely the decay rates should fix things up for you. When you get to the decay rates, try slowing them down in 10% increments.

robz
March 2nd, 2008, 06:25 AM
bump

jfpilla
March 2nd, 2008, 07:19 AM
It sounds like the same problem encountered when a loose converter has been installed.
In addition to TAQ's advice, you may need to up DAF.

ArKay99
March 5th, 2008, 12:45 PM
I had that problem with my old motor. I had a Fidanza and SPEC 3 ~32lbs. total. It drove me nuts for the longest time. It was a 2 part process to fix it. One was when sitting still and tapping the accelerator. The engine would slow down and go right past the idle set point to around 200 rpm and sometimes stall, sometimes recover, then hunt. The other was when coming to a stop and I let my foot off the accelerator the motor would just drop.

Part one was fixed by playing with the throttle follower. I made the adjustments to B4315. Mostly in the 1.52 to 3.55% TPS cells. I mostly raised them, but if you go to far the motor will take a while to settle and it will bounce or surge.

Part two was done by playing with the throttle cracker. I made most of my adjustments in B4309.
1st thing was put a number of 3.4 in the 400 rpm column across the board. It helped when the motor tried to fall on it's face when gliding to a stop from any speed.

Then I put some large values, like 3 grams in all the cells from 0 to 16 mph and from 400 to 2800 rpm. While logging and linking to that table I watched the throttle follower PID tracking the values in the table. Then when I let off the gas pedal to coast I saw the PID decay to zero from that value and the motor would start to fall on it's face, but not completely. Then when I hit the cells around 1000 rpm and 4mph, the engine would pick up and go to around 1400rpm's and the PID would go to the 3 grams I had in that cell. What it used to do because there was a 0 in that cell was try to die. So what I did was just adjust the airflow value to keep the engine around 1000 rpm at that point and multplied the decay in B4313 by -50% to get .0352. That fixed it and I never had it stumble again.

I kept the high values in the 400 rpm row though.