Hi,
im exploring my Fuel trims, Scaling & Latency on Sard 850cc injectors.

Pls kindly advise me as ive 2 scaling with different Fuel Trims Low & In Use.
Latency (Fix) = 6.120 / 3.120 / 1.992 / 1.320 / 1.008 / 0.672 / 0.408

Scaling :
1) 860cc = -4.65 Low & In Use during Idle and Crusing varies -0.18 ~ -3
But Idle AFR 12 ~13.5

2) 943cc = -4.65 Low & In Use during Idle and Crusing stays at -4.65
But Idle AFR 14.5 ~ 15.7

Which 1 should i choose?

As my actual AFR (AEM WB) doesnt tally with my Fuel Map AFR.

Have tried few different Latency values from the Merlin table but this is the closes WB AFR to the ECU AFR

 

you shouldnt be aiming to match WB AFR to Map AFR. instead you should be trying to get your fuel trim to as close to 0 (zero) as possible.

Scaling relates to cruise and latency relates to idle. So:

- if 20 minutes of cruising gets you -3% in fuel trim, then you need to adjust you scaling accordingly
- if 20 minutes of idle gets you -4.65%, then you need to adjust your latencies accordingly

For me, my fuel trims never go flat, but after 20minutes it will hover within a range and you use that as your basis

also, if your injectors are 850cc, then there is no way you can have the scaling higher than that. you should be starting at 15% less and work your way up or down accordingly.

for me, rather than guess the numbers, i use the trims to tell me what to do. for example, if 1.008 for idle results in -3%, then i reduce 1.008 by 3%. if it was positive, then i add that positive amount.

hope that helps

cheers

 

Thank you so much EvoIX,
but if i go lower than 943cc scaling, my car will idle richly.
Say, if i go for scale of 835cc, my idle AFR will at the 12.5~13.5 AFR range which really consuming alot of fuel but the trims is closer to "0" compare to -.465
What should i choose?
Example, ff i only adjust 1 Value (1.008) on the latency table will it effect the whole table and should i also reduce the whole latency table by 3% once ive changed 1 value on the table?

Lastly, usually from which Latency Voltage should i start to adjust? 4.69V? 7.03V? Or 9.38V onwards?

Thank you.

 

i would go for the 835 setting. If the AFRs are so rich i would check other things like WB sensor, sensor calibration, maf scaling/compensation.

i change it across the board as the only true way to get the correct latencies for the other areas is to disconnect the alternator and watch till the battery voltage drops to that level and check the trims and adjust accordingly.

cheers

 

Hi EvoIX,
i believed ive the correct latencies but can i try maf scalling/compensation instead?
What and which and from which Load% & G/S on the MAF scaling table should i start to adjust?

Thanks

 

this is the thread for maf

https://www.evolutionm.net/forums/ec...hout-pics.html

cheers

 

Hi 07EvoIX,
ive took yr advise and yes finally my actual AFR is much closer to my AFR Map.

My WOT AFR now goes below 11 mark (10.3~10.8 AFR) WOT til redline & high speed run.

But my trims still at -4.65 and my car still stall when throttle lift off on lower rev.

Nevertheless, i feel more comfort as my WOT & High Speed Run AFR goes where i wanted it to be...

 

Hi 07EvoIX,
do i need to re-scale my MAF? Will it help on my staling problem when lift off?

Or should i try to use a plumb back bov instead?

Thanks

 

Your scaling on 850 injectors should be in the 700 range. The reason your car gets too rich when you lower the scaling, is that your latency's are too high.

Lower scaling = more fuel
Higher latency = more fuel

PS once again, It does NOT matter if you fuel map matches your actual AFR.

 

I would definitely plumb the bov back to the intake. This is most likely contributing to your issues.

 

Thank you Boosted Tuning & 92...

 

Hi Boosted Tuning,
do i need to re-scale my MAF? Will it help on my staling problem when lift off?
Will re-scaling the MAF Scale effect my tune map (Fuel & Timing)?
Thanks

 

That depends on what intake you have, but usually, no.

Usually stalling on lift off is cause by either incorrect injectors setting and/or incorrect ISCV (idle) settings.

If you do end up scaling your MAF, it may affect your tune, depending on how much you have to scale it by.

 

Thank you very much Boosted Tuning.

Mi idling without AC on is fine and when AC is on the idle is off as ive set the AC on idle rpm at 1200rpm but in actual its fluctuate from 1000~700rpm...

Will replace a plumb in bov help me stalling problem?

As i dont know whether should i continue to adjust my Injector Scaling & Latency again.
Now my Scale is at 835cc & Latency is 3% down from my 6.120 / 3.120 / 1.992 / Etc
But its seems great and my actual AFR finally managed to go lower the 11AFR mark.

Please kindly advise.

 

The reason your idle is fluctuating is that you cant just raise the idle RPM, without raising the ISCV steps as well.

Yes, plumbing the BOV back into the intake ie recirculate setup, will help cure your issue.

As for scaling those injectors, do this. First, unplug your battery for a min, to reset the ECU and the currect fuel trim data. Then try this scaling:

Scaling 770

latency's
3.312
1.68
1.032
0.84
0.552
0.456
0.36

The idle for 20 mins, then go on a 30 mins cruise. Then report back with the low and mid fuel trims.