Non lock up converter idle issue

[v8-tuning]

Hi
Just installed a non lock up converter in a vs 304 with 4l60e
its had a transgo non lock up valve kit installed .
Whats happening is at low speeds its hunting and sometimes stalling
when coming to a stop.
I tried maxing out and zeroing the tcc tables and makes no difference.
It was fine before with the standard converter had no issues.
I even tried a new tps an o2 sensor and no difference.
So I believe its tine related.
Anyone ever come across this?
Its my daily driver so and its pretty much un driveable atm.
I recorded a log of whats happening.
If I cant work it out might just have to go back to a lock up stall converter.

[Holden202T]

I assume this motor is not stock ?

I can't understand how no lockup in a converter would change anything ... other than lockup, but that shouldn't have any effect till above 70kms or whatever it is.

certainly at the end of the when it stops hunting its showing really rich on the o2 sensor, but not sure how much that is effecting things...

do you have any logs before the converter change ? also what stall is the converter supposed to be ?

[v8-tuning]

Its not stock.
Has a vn group a cam, more comp, come racing ttb manifold.
And stall is a tce 8" converter about 4000rpm stall.
Was fine before I changed the converter.
I tried another iac and checked all the wiring and
hoses cant find anything.
Whats odd is its only when I come to a stop or low speed.
Once you pull up the idle is fine.

[Holden202T]

I wonder if its because the converter has more slip in it as low speeds its changed the RPM/map load point which you never used to see before due to the smaller converter...

do you have a copy of the tune and a log from before the change?

[VL400]

Its dropping in and out of closed loop, and with the BLMs so far off is pulling fuel when closed loop activates and adds it back in when it drops out causing the surge.

[v8-tuning]

Blms aren't really changing a lot even with big fueling changes.
Tried going leaner then tried richer same thing just kept hunting.
Its around 13.5 afr atm.
I ended up disabling closed loop by setting the temp to max and problem solved.
Went for a drive and it drives perfect.
No idea why it does that in closed loop though.

[Holden202T]

try changing the open loop AFR's to something like 14.0 below 2000rpm, re-enable closed loop and see if its any better!

when I did my mates 304 with 286 cam it would surge cruising along, partly was because the cam was too big, gearing wrong but also it wanted more fuel below 2000rpm than 14.7!

[tjwasiak]

From my experience it is better to advance timing then to add fuel at low loads/engine speeds with fatter cams. In fact fatter cam needs less highest advance (as there is more air/fuel) but more advance down low (idle/low load areas) and higher idle speed.

[vlad01]

yeah they do need tons more timing light load low to mid rpm as the VE is lower in those areas compared to a stock cam, so the charge density is low once the valve closes and begins to compress, so it burns slower and thus needs more timing.

[v8-tuning]

Idle timing is 24.96 it idles nice. Spark map as below .
Ive done way bigger cams up to 260 @50 and never had this happen
before. I can try more timing in the 20-50kp column it idles around 45 -50 kpa.