ULTM8Z

I have the idle almost right where I want it. It's pretty dang smooth now. Only thing is, when I go to shift from Park to Drive or Neutral to Drive, the engine will want to almost die, then it'll kick back up, struggle hard against the converter and then settle down and idle smoothly again.

My idle speed is 650 rpm with an additional 100 rpm when in Park/Neutral. At steady state idling in Park or Drive, the idle is really solid. But shifting from Park to Drive, there's this issue.

Question: I remember reading somewhere on this board that the stall saver was found to actually induce a stall. I forget who it was said it and I can't relocate the post. Should I be zeroing out my stall saver? If not, what is a good RPM for it to be set at? I tried playing around with it, but couldn't get it to really make that much of a difference.

My IAC motor is new, throttlebody has been cleaned out, etc. Scanner shows all sensors reading normally with reasonable output values. I love the idle quality right now and hopefully won't have to compromise it to solve this issue.

RednGold86Z

iTrader: (1)

Could try some more spark advance at RPMs below idle. Maybe a few more IAC steps for drive (or a few less for park/neutral, however you want to look at it). Maybe run a more open TB with less IAC steps. Might even be able to make a difference with some IAC->Fuel.

But, I think you'd be most happy with a 2400-2600 RPM stall speed torque converter, hehe.

junkcltr

iTrader: (1)

When I first installed the $58 BBZB I had a stall condition when going from park to drive. It would also stall when the large coolant fan would kick on.

I tried more spark advance but it only helped a little. I then increased the AE vs. MAP delta so give it a pump shot when going from park to drive during the change in MAP. That worked for me, but it was because I could see the WBO2 go a little lean on the park to drive condition. The VE tables were OK under static conditions.

Grumpy

At 650, you're not leaving much room for error...

In the grande scheme of things the IAC is kind of slow, so you might try playing with the idle spark, rpm corrections, and see if that helps. Be sure to try 0, first, and gradually play with the advance/ retard numbers.

Does your code have a transition IAC cnt adder?. That will add counts, without waiting for the engine to almost stall first.

Also gotta remember, you need to give the engine what it wants, and that might not be what you think it should be.

FWIW, for years I used 0 cnts at idle in gear, but now with everything being really correct, I'm using ~25..

ULTM8Z

Would that be the Idle timeout Steps vs Coolant Temp table? I've always wondered how this table worked?

I'm also running about 25-30 counts in gear.


Also with the SA correction vs idle speed error, it appears to be non-proportional function... from what the scanner shows, it basically adds or subtracts all of that SA or nothing. Am I seeing this correctly?

I'm running about 34 deg nominal SA at idle.

RednGold86Z

iTrader: (1)

That's a lot of spark for your combo. What advance is in the tables in higher loads at idle RPM and below? If it drops off, well there you go.

I like to actually idle in a little bit of a hole in the map, where a little more load and also a little less RPM has a little more advance built into the table. It also allows the idle spark stability to function - because if there's too much base advance, adding and subtracting timing both REDUCE rpm = not stable. It's a slight trade off, but the benefits outweigh the economy difference.

I think the mini-ram guys also have to consider the bank to bank fuel difference with the throttle blade settings. A properly tuned IAC control (and VE/MAF and spark tables) should be able to overcome the typical disturbances without requiring too much diddling with the TB.

Do your INT and BLMs go up when you put it in gear? May be a sign of VBatt injector offset problems, or maybe MAF table problems.

ULTM8Z

Not at all. My BLM is a rock solid 128 in or out of gear.

Here's my advance table. Oops...it's actually not 34 deg... typo.. It's actually more like 31-32 deg.

Grumpy

True,

That's alot of timing for idle.

ULTM8Z

Grumpy, I know you always say "give the engine what it wants". So in this case, it may not want what I think it wants... But given my engine combo, what do you think "should" be a reasonable amount of advance?

$8D, Miniram, AFR 180 heads, 10.1:1 compression, 212/218 cam....

69 Ghost

iTrader: (1)

I was having the same problem and once it warmed up it seemed to fix itself. I always thought it was my tune but I ended up with a bad bearing in the alternator and the Idler arm on my serpentine system. Apparently if the idler arm bearing goes bad it will cause the alternator bearing to fail also. Not until the very end did it ever make any kind of noise to speak of. You can replace the idler bearing by getting alternator bearing from Auto Zone. Try a 203FF from Timkin for the alternator if you are running a 12SI or if you are running a serpentine for the idler.