LT5 hesitation...

[Schrade]

... which Marc says ALL LT5's have...

I still have a small amount of water in my tank - hardly noticeable, and it will all be out after a few more drives.

But something came to me here this morning, related to the residual water. When backing uphill, up my driveway, she struggles. Warmed up, it's not noticeable even.

But backing uphill cold, RPM's are probably right about 1.6% throttle. Which is where DataMaster showed the hesitation, and LOPE - from 1.6 - 2.4% TO. LIKE a vacuum leak, if throttle linkage is HELD at that throttle position... Like the pulsewidth / gas isn't sufficiently calibrated @ that throttle position... http://www.zr1.net/forum/images/icons/icon5.gif

Now I have a little water still mixed in. Even LESS gas, exacerbating the problem.

The water isn't the issue, because it will shortly be spent.

The issue is the pulsewidth calibration at that TO %.

Any thoughts here on increasing the pulsewidth at the 1.6 - 2.4% TO position???

[Schrade]

Good question huh guys...

Anyway here, the water is gone. Took a ride, backed up the driveway, smooth as silk again - except for that light 'bump' at 1.6% - same as usual, that Marc says every one of 'em has...........................

http://www.zr1.net/forum/images/icons/icon5.gif

With a stick, you're well over 2.4% TO, when you let in the clutch. This automatic has no choice. A stick won't see it unless you're in the garage.

[Hog]

What torque converter are you running?

[Schrade]

It's a Precision Industries piece there Hog - pretty stout piece (for $9C, it oughtta' be).

2300 stall...

[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?

[Schrade]

Does it Closed Loop too there Hog.

Only the left-over water in the gas tank exacerbated the glitch, because fuel calibration I think is not correct for that TO % range.

DM log (CL) showed SA @ about 16' as it hit 1.6 TO, and then when it exceeded 1.6%, up to 2.4% TO, it bumped up to 25', then up and down, until TO % exceeded 2.4%.

DM video is here, lope starts at 2:53, as TO hits 1.6% (http://www.youtube.com/watch?v=ahqv0vs1Y1o)

Marc looked at it when we talked about it, AT LENGTH, and he said they'll all do it. I can't argue with him on it - he knows better than I do.

I'm not satisfied tho'...

[XfireZ51]

The C/L Threshold for Idle is 1.95% TPS, right in between your 1.6-2.4%. So the ECM is straddling idle and open throttle operation. That means its also jumping between C/L idle spark advance and open throttle tables. In addition, it sounds like a bit of a lean surge which the BLM look like at idle. A log or spreadsheet would be better to review.

[Schrade]

The C/L Threshold for Idle is 1.95% TPS, right in between your 1.6-2.4%. So the ECM is straddling idle and open throttle operation. That means its also jumping between C/L idle spark advance and open throttle tables. In addition, it sounds like a bit of a lean surge which the BLM look like at idle. A log or spreadsheet would be better to review.

What's up Dom...

I haven't figured out how to plot / grid values in Windows; much less Linux; still reading there.

Just needs a little more thought here, and my CPU stays pegged ;)

[XfireZ51]

What's up Dom...

I haven't figured out how to plot / grid values in Windows; much less Linux; still reading there.

Just needs a little more thought here, and my CPU stays pegged ;)

DM must have a way of creating a .txt file from the scan.

[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.

[XfireZ51]

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]

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.

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]

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]

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.