Decelerating air/fuel ratio

Run through the DFSO (Decel Fuel Shut Off) Scalars...

What ecu?
What is the current AFR condition?

interesting.

If you want to mess with DFSO, then you can get started by copying all the settings for DFSO Scalars from the X3Z, over to your A9L.
Maybe even try loading up a X3Z.bin to your A9L?

What .bin editor are you using, as most programs use slightly different names?

Basically you are looking at all settings that have the term 'DFSO' in them.
Do a comparison between a stock A9L.bin and an X3Z.bin and all of these scalars will be easier to identify, as the A9L does not utilize DFSO. (iirc)

As far as I know, that is correct.

I have confirmed that the X3Z DFSO settings allow fuel shutoff, but I have not run an A9L myself to confirm.

Others have had to use the X3Z settings in order to get DFSO to function....

jason



EDIT:
CalEdit will give you headaches.... I suggest upgrading to BinaryEditor... it'll set you back a few bucks, but it is worth the ~ $55...

the way i see it, the EEC doesnt target a specific AFR while "decelerating" it operates the same during normal driving, goes off MAF flow and uses the injector slopes to calculate the PW to match the fuel trim. its up to your slopes to be accurate to deliver correctly under all the usable PWs you will see.

if your maf curve is accurate and if your getting lean or rich AFRs on closed throttle decel thats indicating low slope or injector offsets being off. reason being your lowest PWs are going to be under closed throttle decel, the higher rpm with low airflow means a smaller PW is used, since higher rpm means there are more injector firing events in a given time. so a smaller PW is needed. if you datalog and watch closely. while driving around at light throttle. the engine RPM will increase, but the airflow usually remains close the to same, so the PW will get smaller as RPMs rise (as long as airflow doesnt change too much)

so the error on decel is due to the low slope or offsets, since those have most affect of the short PWs

think of it this way. the smaller PWs are going to be during high rpm/low airflow conditions, and the longer PWs are going to happen under low rpm/high airflow scenarios.


i had a problem with going pretty rich on decel, into the 12s, CL would command a lean lambses (like 16-17) and once i tippied back in the throttle, since the lambses was leaner, i got a lean tip in, most of the time it wasnt so bad that it would hesitate but it did do it sometimes. but the CL was sluggish to correct this lean condition, so it would hang leaner for a few seconds.

i played around and got some different slope values to work. now my car accurate delivers fuel all the way down to around a 1ms PW then it starts shooting leaner, according FRPP injector specs 1.1ms PW is the smaller "repeatable" PW. so i contribute that leaner afr at the LOW pws to the injector being innaccurate.

also i am sure that the fact i am running 42lb injectors on a N/A 302 isnt the ideal combonation (going to use them for turbo project, so i am just using them at the moment) if i had smaller more "matched" injectors, i wouldnt be logging near as low as PWs.

but the lean at LOW pws doesnt bother me really, it takes a fairly high rpm closed throttle decel to get it to start getting leaner, and eve when it does, CL will command rich to compensate. then when i tip back in the throttle, if anything it has a slightly rich tip in, which i can live with, you cant feel it, plus CL is quick to correct the rich tip in i have found.

just play around with slopes and stuff. but honestly if its not so bad that you dont get bad tip ins or anything, you may not even mess with it.

also, get BE and EA

Keep in mind too that at a certain point during higher vacuum deceleration, the injector PW is completely cut causing a dead lean condition.

the common 87-93 A9L and A9P eecs dont use a DFSO feature from the factory, it can be enabled though.


the XZ3 from the cobras and the CBAZA strategies use DFSO. and i am assuming all newer computers use it also.