AFR unstable, idle hunt

[diracdeltafunct]

I'm trying to create my own AFR and VE tables. Using the advanced fueling I get highly variable and highly unstable AFR readings.



As the AFR value fluctuates it doesn't move outside of the 1.47 Lambda cells in the AFR table. In the ignition table, it stays mostly at 11.0, but in the start moves between the 11.0, 10.5 and 8.5 cells.

Is the cause of this obvious? What should I change?

[redmkiv]

Your AFR ´s are very high = lean, in closed loop normally Lambda is ideal 1.00, Ignition table is not really for driving.....
Engine? Car? tell more.

[diracdeltafunct]

Your AFR ´s are very high = lean, in closed loop normally Lambda is ideal 1.00, Ignition table is not really for driving.....
Engine? Car? tell more.

So I should change AFR to 1.0 for the cells that would be used for idling?

However, even with the current AFR values being high, should it not be able to keep the high AFR values consistently? Why would it oscillate in this manner between high and lower AFR values? Is it an indication of a different problem?

Engine: 3S-GTE
Car: Toyota MR2 MK2 Turbo, 1991

[clem]

What do you know about engines? There many things can go wrong if you dot know what you do.
Yes, Lambda 1 is soichiometric combustion, 0,9 gives most power and 1,1 best efficiency (for gasoline), look that up in the net. at a certain lambda value it is not possible to burn the mixture anymore (lean limit, rich limit).
In Advanced mode there is a charge temp estimation table - did you configure it? If there is a sharp edge that might be causing your problem. IAT correction tuned properly? Your Ignition values should be much higher. Too less ign advance (negative advance is definitely too less) causes very high exhaust temps! Do you know the engines OEM ign map? Mine is pretty much the standard map except of the idle area. Tuning the VE and the target Lambda table correct will help much for good idle
After correcting the mentioned things: try to drive your car in the idle region (map, rpm), take a break, tune it from the log and drive again.
When standing still with a good idle, watch IATs and AFR climb due to heat soak. When IAT is 10° higher than driving IAT, configure IAT correction table for correct AFR and extrapolate it for a good first estimation.
this is what my maps look right now, and car has pretty solid Idle (hours and hours of tail-chasing tuning!!! no stable idle -> no good tune possible -> no stable idle -> ...)
SR20DET with 260° in and STD exh. camshaft, pretty much finished tuning up to 0,4 bar of boost, without NVCS, idling at 900 RPM & 46 kPa:

here are some good advices for idle: viewtopic.php?f=19&t=517&p=3525&hilit=i ... ream#p3525
Also there are numerous tuning guides online available, watch some of them and get an idea of what it is about.

Just make enough efforts and you probably wont kill your engine immediately

kind regards Clem

[Kisielisodd]

I think that you mistaken values on AFR/lambda map. 1.47 value is not AFR 14.7 it is lambda 1.47 = 21.609 AFR !!!!

Select whole map and change values by multiplication 0,68*

[pepifebles]

Mi car also its 3sgte rev 3. I attached my ve, afr and ignition map. Runs a little lean but I'm sure that is better than you and hope you find useful.