Delco tuning for for dummys

[VL400]

There may be some different VR/VS ECMs, I know there are some different 808's around. Can leave the jumper on if it works, it wont damage anything.

[Dec_head]

I need to slap myself up the back of the head the 8 cyl jumper had fallen off at some stage and i think that was the cause of my problems.

[Dec_head]

I am a little dazed and confused as per usual have a few questions i am not quite clear on
1. the target afr on the dashboard when logging i start the car it is like 10 when cold then gradually changes does this mean the tune is trying to to get to that afr
i know i have asked earlier on about it being changed but it is still a little unclear if the target afr is 14.7 then you should see around 450 on the 02 ? so if my target is 12 at wot would i then want to see something like 600 on the 02 ? is that how it works ?
2.Also with the ve learn how long does it take to apply changes and when does it apply them and how ?


At the moment when i start the car cold it stays around 450mv on the 02 and goes quite well then as it warms up gets richer and seems to stay around 7-800 wich i figured was safe enough but now i want to try and get it leaned out a bit more and experiment just unsure.

[antus]

1. the target afr on the dashboard when logging i start the car it is like 10 when cold then gradually changes does this mean the tune is trying to to get to that afr

Yes, thats the calculated target AFR, which includes cold temp enrichment and so fourth for the cold engine. its only useful to a point due too....

i know i have asked earlier on about it being changed but it is still a little unclear if the target afr is 14.7 then you should see around 450 on the 02 ? so if my target is 12 at wot would i then want to see something like 600 on the 02 ? is that how it works ?

Its a bit more like

O2 graph greyed.GIF

that kind of shape, so you can see that its going to be most accurate at 14.7, and no so much either side (its range is narrow = narrowband). This is also why in a standard tune learning only works at 14.7 AFRs, and it also means that you have to take the 'target afr' when its far from 14.7 more as the ecus wishful thinking. It'll get it in the ball park with all its internal equations, but it wont get it to exactly 10 and hold it there from the O2 sensor. Your going to have the same problem trying to tune to an AFR of 12 yourself. A wideband sensor is required.

2.Also with the ve learn how long does it take to apply changes and when does it apply them and how ?

Its quite slow. It only makes small adjustments. So every time it sees your miles out it'll make a 0.1% (guessed value, something small) adjustment only. This means that if there is some electrical interference or something goes wrong its not going to screw your whole table. Instead its going to very gradually improve. As a real world example this might be enough to keep up with a gradually decaying air hose or slowly failing fuel pressure reg, which is what the blm system is designed for.

[VL400]

Adding to the narrowband info, the sensor only does something when the target AFR is 14.7:1 and all the closed loop related qualifiers are met (check out the XDF). Anytime its not 14.7:1 there is no feedback so its called open loop. When cold the narrowband sensor has a high internal impedance so will show up as 450mV. During closed loop you will see it swing rich and lean (200ish to 700ish mV) due to the response curve that antus posted and the way the ECU controls closed loop with the catalytic convertor.

During open loop operation if your VE and all the modifiers are spot on then when the target says say 12:1 then it will be commanding and achieving a 12:1 air to fuel ratio. When tuning you want to get the wideband to read what the target AFR is. From there if you decide you would prefer 12.5:1 you just change the target AFR table. During closed loop the BLMs try to keep the AFR at the 14.7:1 target - the idea is to adjust the VE until the BLMs have a smaller influence and hover around the 128 mark.

Leave the cold start tuning until after you have the finished the operating temp tuning

[Dec_head]

Thanks makes it a little clearer guess i should buy a wideband been holding off on it but i now have some pacemakers and blue top injectors 3.45 diff gears etc to go into it.
Still need to do something about the air induction though i took it for a drive tonight and i was watching as the air intake temp went up around 115 the 02 voltages went up to like 8-900
When cruising on 80 k's the air temp come down to 74 -90 degrees and the 02 voltages dropped as well down to 650 -750
So hard to find a inconspicuous bonnet scoop that looks decent i might have to make one up myself

[Holden202T]

yeah everyone i talk to seems to rave about these inlets:



but from a tuning point of view i hate them

[Dec_head]

Yeah seriously thinking about designing a fibreglass cai or low line bonnet insert to overcome the heat
Be pretty pointless having a decent inlet manifold if your air temp is as high as mine
I like the way mine goes when cold but as it warms up i might as well have a stocker it turns into a pig not that the tune would be helping but still

[Holden202T]

well when you think about it, all the old v8's pretty much run this setup and its worked for years! i think its more a matter of working out MAT temp adjustments etc (which i've been thinking about lately) but your right, if you could make a CAI type shield that meant the air filter gets cold air from above the radiator rather than from the engine that would be a much better option!

you could always do like the toranas used to, have a scoop on it and then make a box around the air filter so it seals the box to the bonnet and then only draws in cool air from the scoop .... mind you this assumes you want to have the look of a scoop.

another possible option too ... get one of those adaptors you put on the carby which then gets fed by a turbo/supercharger and just run a pipe from it out to an air box or something like that ?

[Dec_head]

Yeah undecided was thinking of the vk brock air tray style or one of those impco alloy adaptors for gas and adapt a longer pipe onto it off to a filter somewhere else.
After looking at the limited bonnet scoops available for the vr vs i might make a mould when i am done and pump out a few fibreglass inserts and custom air trays .
If i ever get the time million projects going through my head