ok so i am pretty much a n00b at tuning but i was wondering. yes i have tried to search this but nothing came up. I was wonderning if anyone knew of any good sites etc to learn about tuning fuel trims.


Thanks in advance

 

I am n00b as well... Hehe..

Here is what I did in my car:

1. Log the data for a week after flash... I monitored Low, Mid, High Trim. (Make sure you do not flash in between. Otherwise, it will reset to zeros).
2. On mine I saw up to 11% addition of fuel in Low FT. Simply I try to reduce the injector scaling by 11%. The stock was 513 cc/min. Muliplying 513 * .89 gave me 456.5. So, I reduced the injector scaling to 464 or something (You will know if you use "-" on the keyboard to reduce the value). Then, it was subtracting too much fuel (Again, logged for a week).
3. Finally, I set it @ 472 and it only went -3 % at the most. So, I left it... That is 92% of the stock injector size. It means that the scaling will open injector a little longer to add more fuel than if you set "Injector Scaling @ 513".......

 

I did the same thing on my Evo 9. It seems that a lot of modded Evo 9s do not like the stock 513 injector scaling. I also set the scaling on mine @ 472. The 464 scaling was subtracting too much fuel. 472 did the trick.

It would be interesting to know if this is happening to all Evo 9s, but owners simply do not log trims for an extended period of time to know about it.

 

This site has a ton of info.
You can try searching fpr malibujack posts.
Or you can also go to active matrix forums, there's some info there too.

But seriously, info on trim tuning is abundant in the ECUFlash section of EvoM.

 

thanks guys i will try to find some stuff on here

 

does any one have any other sites i can use

 

come on guys anything else to help me learn about fuel trims

 

Read the thread on injector scaling for larger injectors in this forum. Look for posts by l2r99gst, malibu jack, razorlab etc. Very useful.

Also, have you logged fuel trims, what are you seeing. If you think you have a problem, post them.

 

also if i some new mods on my car and want to tune it myself do i still do logs and then tune it

 

Yes if you add parts that will increase engine power/ performance, you will want to address fuel, timing etc. My amatuer advice: research this forum, log first, get acquainted with what you are logging and interpreting results. Then begin reflashing. Baby steps.

The difference between this forum and others on EVOm is that everyone is very helpful. Research a little first though.

 

If the mods would sticky more threads in the forum, we wouldn't get these questions over and over.

But, as many people mentioned, there are very good threads and posts in this forums on fuel trims and injector scaling and how to properly tune for bigger injectors. You may just have to search a bit and read a lot, but in the end, it should be all good reading and a chance to learn.


Eric

 

hook a brother up?

for some reason this forum only goes back 7 pages...

linky linky? :P

 

I was under the impression that MAF Scaling would resolve fuel trim issues.

I used OBD ScanTech to log STFT and bumped up most of the lower Hz cells by anywhere from 5-15%, that seemed to resolve my STFT issues.

 

quick question, would having the low fuel trim closer to zero(mitsulogger) or 100%(evoscan) be better on mileage then having it at say 8 or 125% and having the STFT running richer? my mid trims are about 106-107% but my low are about 125% via evoscan. my STFT is usually around 100% crusing but at idle it hovers around 85-115ish. I have played around with the scaling and latency and this is about the best I can come up with without drivabilty issues. I haven't tried to adjust the cels in the 500-1000 in the fuel table to compinsate yet I was just wondering if I did would my mpg change at all?
ed

 

The Fuel Maps are for open loop only. During closed loop, the front O2 sensor will always adjust for stoich (unless the engine's still cold, in which case it will run richer).

Closed loop tuning is really just trying to re-scale the MAF & injectors so the system doesn't have to make so many corrections. You may see some improved MPG with proper injector/MAF scalings, but this shouldn't really be affected by the fuel maps as they are open loop (ie, mid-to-heavy acceleration only... not cruising or idle)