LT5 hesitation...

[XfireZ51]

Originally Posted by mike100

Like i suggested before- if it has a lean stall tendency stock, definitely program in some 'pump shot' in the low rpm range to see how it affects your auto equipped car.

Mike,

I think the AE is a temporary patch. This is recurring and oscillating idle.

[Schrade]

Originally Posted by XfireZ51

Mike,

I think the AE is a temporary patch. This is recurring and oscillating idle.

I think this AE IS in order too here, as soon as I figure out how to do it, and how to UNdo it, if not a solution........

[XfireZ51]

Originally Posted by Schrade

I think this AE IS in order too here, as soon as I figure out how to do it, and how to UNdo it, if not a solution........

Not suggesting AE shouldn't be increased. If there is a bog on tip-in, then yes.

[Schrade]

If 1.95% throttle is still considered 'Idle', then coding for an AE bump at that point couldn't be written in???

Or could it?

0% throttle is still rock steady - in O/L AND C/L.

Is there a definition for 'Acceleration', in AE?

[Schrade]

Originally Posted by Hog

Very nice, the Vigilante is a high quality piece.

Since this occurs when the car is cold, sonds like you'd need to do some Open Loop tuning.

Does the A/C compressor loading affect this issue at all. Better with A/C On vs. Off?

Whats your timing advance doing at the 1.6-2.4 TP opening?

I missed the A/C load experiment Q here Hog; will do shortly here...


ed.:
Same behavior.

Light pedal, accelerating down my street, and again, when the auto shifts, and throttle drops to just above idle. Ever so slight lope, until acceleration (over 2.4% TO).

[XfireZ51]

Chuck,

16d SA is the stock setting for Closed Throttle SA. Then your SA bounces up to 21 or so which is probably what is in the PT Closed SA table for near idle rpm/kPa. And the ECM is swinging back and forth between the two. You can flatten the SA table so when u transition from Closed Throttle SA to the SA table it's a smoother transition. Also, I would lower my IAC counts at idle. With the engine warmed up and in C/L, you'd like to be somewhere in the 5-15 range.
Make sure you reset the TPS v when u do that.

[Schrade]

I follow what you're saying there Dom (except for how to adjust IAC). TPS voltage I can set too.

But, is there no circumstance - no condition, which dictates any SA BETWEEN 16, and 21???

In other words, ... are you believing that when the timing advances for higher rpm / higher TO %, that THIS is causing the RPM's to go back down???

And what's the significance, if any, of DM readout not showing anything between 1.6% TO, and 2.4% TO?

I plotted TPS voltage vs TO%, and voltage increase did NOT show a corresponding jump.

And remember, I increased throttle with an 8mm wrench on the TB stop screw, in PERFECT increments, 1/12th of a turn at a time, to ELIMINATE mechanical error.


ed.:
I won't be able to ask the right question, until I get values plotted in a grid...

[XfireZ51]

I am not clear how this very specific circumstance manifests itself in your driving, but the answer to your question is that there is a transition between Closed Throttle SA and SA used for driving operation. That's dictated by the %TPS opening, which in the stock cal is 1.95%. Once that's exceeded, the ECM moves to the SA table. The TPS mechanism is a rheostat, so there are "jumps" in voltage as the contact moves from one coil to the next. It won't be absolutely linear.
As I said, I flatten my SA table in the area circled red in the attached .jpg. Or I keep it very close to smooth out the transition. Attached is a pic of what I am describing. This is from a stock calibration. Its almost exactly what you see in your DM log.
As for setting the IAC count for Minimum Air, the procedure I follow is:
(Do this procedure once you have warmed motor to C/L operating temps. otherwise it may very well not idle. Also, you will have converted your throttle stop stud to a hex bolt)

1. Jumper the ALDL as you would for reading codes.
2. Turn ignition to ON, not start.
3. Leaving ignition ON, remove the IAC harness connector. This fully extends the IAC pintle and closes off the IAC port.
4. Shut ignition OFF and remove the ALDL jumper.
5. Start the motor and get it to idle. May need to use a bit of throttle at first.
6. Check idle rpm. Turn the throttle stop screw until the motor is idling at an rpm just below what your target idle rpm. I want my idle at 875-900, so I set Min Air throttle at 800-825rpm. You may need to adjust TPS Voltage so that ECM stays within idle TPS Voltage range.
7.Tighten everything up and shutoff motor.
8. Plug in IAC. I also undo the negative BATT cable to drain the ECM memory.
9. Reconnect BATT turn ignition ON, and check TPS V. Adjust to .53-.57v if necessary.
10. Start motor and quickly raise to ~2000rpm for a brief period. This resets the IAC.
11. Shutoff motor, then restart. Allow motor to idle down and check your IAC counts and your TPS Volt which may need to be adjusted one more time.