simon k wrote:
I'd actually interpret the difference between the two needles above as the blue one being "leaner" than the brown - the basic shape of it is the same apart from the first few stations, meaning that if you set them both for the same AFR at WOT, the blue one would be leaner at idle & cruise
I think I just need to clarify, in my last post, the image is of data all running the same needle. There are two "lanes" of traces:
* the top "lane" which has two traces in the same lane is a plot of Manifold Pressure (light blue) and Engine Speed (red/brown)
* and the lane showing just one trace is AFR.
Check the legend in the top right of each lane.
The lanes all line up by time too - if you look vertically up and down the traces in ALL of the lanes, this represents data from the same moment in time. If you look right up the top of the image you will see time stamps.
morbo wrote:
I think (hope) that the two circumstances that need enrichment will turn out to fall on the exact same section of the needle. If so, I should get this pretty close. [If not, it means that I am already compromising and that in order to get the sudden WOT AFR rich enough I would have to over-richen some part of the cruising AFR].
simon k wrote:
keep trying, but I reckon you'll find that there is no needle profile you can either buy or make that will give you everything you want in every circumstance... The HIF44 on my NA motor has really nice AFRs all the way from idle to WOT at 7000rpm, but I still see the needle flash to 16:1 if I nail the throttle at 2500 rpm in 2nd gear. It doesn't hesitate, and accelerates strongly. The only way I know it goes lean is because I have a gauge that shows me. If I didn't have the gauge, I'd think it was perfect and move on with my life
I think you're right on both counts...I don't think I'll be able to eliminate the sudden WOT lean condition and I may already have reached the best case scenario, but I'll see if I can tweak it further using the endoscope to figure out the exact part of the needle to alter. And I have no hesitation on pinning the throttle most of the time either (theres no longer any hesitation and it used to happen only under very specific circumstances). I wouldn't think there was an AFR problem at all if I didn't have the gauge.
Given it's forced induction though, I feel like I have to play it quite safe. But I don't really know...perhaps even for a boosted engine it is quite acceptable to have those spikes? Any advice is very welcome. My natural thought is boost + WOT + lean is bad and should be ironed out but maybe I'm being too anal about it?