How do I know butterflies are synced?
So I’ve had my system on my 351 Ford Cleveland for a year now. My IAC I have got them to be 3-10 but when when I drive the car hard and let go of the clutch, put it in neutral and break hard the Rpms drop way too low to about 540 Rpms almost dying. It will not die but I hate that it does this. It’s a 3 speed manual and a weekend car so when I do drive it I like to drive it hard. Accelerate hard push it to 5k rpm and then de-engage the clutch to come to a quick stop. I had no problem with a carb when I would do this. Why is my fitech doing this? Are my butterflies supposed to open equally/simultaneously when I pull the throttle linkage? My set idle is 750 but the car drops to 580-640 Ish and it sucks.
The butterflies open simultaneously.
I take it that it does achieve a steady idle at the requested 750 in the driveway and it is only on over run from higher revs that you have your under rev problem ?
Here are a couple of tuning settings you could play with. (best one at a time)
a). In Rev Limit Decel Cut ( main menu> pro tuning> initial setup > rev limit decal cut )
try setting Dfco Enable Temp = 300F ..... this will de-active fuel cut on over run and make it behave more like a carby
It could be that the fuel isn't cutting back in soon enough on over run and hence the low revs. The above is the quick fix as it turns off the cut out on over run completely. (it is the first thing I do when tuning a car as wrong settings have confusing effects, and then I also usually end up leaving it that way)
b). In Idle Control ( main menu> pro tuning> initial setup > idle control )
have a look at Decel IAC Decay ... the default value = 0
This controls how quickly the idle air control steps, added when you open the throttle, decay back to the remembered last good idle setting steps.
Smaller numbers (they can be set less than 0) mean quicker decay, large numbers mean slower decay.
If the decay is too quick the engine can die, if the decay is too slow the engine will "push" on over run and might be revving too high initially when you pull up.
add a fair old chunk from where you are now (say +40) and see if you notice the difference (it should be noticeable just revving it up at a standstill as it should take longer to settle back to idle)
I would try what Robanzac is suggesting above. You can follow this procedure to set idle, which will also take care of syncing the butterflies:
This will be done with the engine off and key does not need to be on.
1. Disconnect the throttle peddle from the throttle body, so we know it is not moving or holding the throttle.
2. Unscrew both front and rear adjustment screws so they just come off of the pivot arm stop.
3. Starting with the front screw, screw the adjustment screw in until it touches the pivot stop and you just see the throttle arm/blades just start to move. Once you see this movement screw the screw in ½ turn (If the engine is pretty stout go ¾-1 turn in)
4. On the rear screw we are going to do the exact same thing, screw the adjustment in until you see it touch and move then go a ½ turn (If the engine is pretty stout go ¾-1 turn in)
5. This will set the blades close enough to start and warm up for final adjustment. We just want the engine to idle, if it is high that is ok until it warms up if it is low and wont idle go in a small amount on both screws until it will idle.
6. Turn the key on do not start, at this point we want to clear the leaned data that the car has learned previously this way we can have a clean slate when we start. Go to Go-EFI Initial Setup then go to Reset Learn, inside reset learn go to Reset IAC Data by switching the 0 to 1 and hit send to ECU. This will erase all leaned data but will not change any of your base settings. Turn the key off for 30 ish seconds.
7. Start engine and let it warm up to 170 degrees F then look at the IAC steps on your dashboard. With the engine running and the temp at or above 170 adjust accordingly. If the IAC is above 10 you will screw in both screws equally until the IAC steps falls below 10 but does not sit on zero. If the IAC steps are staying on Zero and the idle is above the desired setting you will unscrew both screws equally until the IAC jumps back and forth from a number under 10 but not staying on zero and the idle is at your target RPM.
8. While you are making your fine adjustments keep an eye on the TPS value, if it goes above 0 shut the engine off and let it sit for 30-45 seconds. Turn the ignition back on and go into Go-EFI Initial Setup then go to reset TPS Learn, inside reset learn go to Reset TPS Data by switching the 0 to 1 and hit send to ECU. Continue with the throttle blade adjustment.
9. Reconnect the throttle cable/rod.
Decel idc decay minimum value 0 maximum value 1. ?? Do i need a software update? 0-1