Fuel Trim's Don't Make Sense- Help

[joneze93tsi]

Be forewarned I am a NEWB to tuning.

Here is my dilemma:

Car seems to use ALOT of fuel. cruising 70-75 I see 710-720 on the greddy EGT guage. (1310-1320f).

These seems exceptionally cool.

Also did a 1500RPM - 7200~ WOT pull in 3rd gear netting MAYBE 730c


So I hooked up the logger and the fuel trims would seem to indicate me, it thinks its lean:

Fuel Trim Hi: 135%

Fuel Trim Mid: 114%

Fuel Trim Low: 132%


Any help would be most appreciative!

Thanks
Shawn

 

[joneze93tsi]

OH yeah..this might help.

Its a 93 Tsi AWD

2G mas all honeycombs in,
550cc Inj. MKIV SMIC ect.

All 0's across hi/lo on the AFC.

Just starting to tune.


Running 15psi.

TIA
Shawn

 

[Bohrn]

well, your high trim does seem a bit lean for sure. you could put in a few more percentages of fuel with your safc on the upper rpms

I like a lean low and mid trim as you get good mileage and nice throttle response. But your low might be a bit low. If you can add a bit of fuel there that would be good. Just a percent or 2 tho. Let it go for a week and then have another look.

 

[sqhopeful]

I too am a tuning newb, i found this on a search to try an find out what the fuel trims should look like.......

if you have 550's and a safc on zero across the board, how are you lean?

 

[nine5raptor]

Originally posted by joneze93tsi
OH yeah..this might help.

Its a 93 Tsi AWD

2G mas all honeycombs in,
550cc Inj. MKIV SMIC ect.

All 0's across hi/lo on the AFC.

Just starting to tune.


Running 15psi.

TIA
Shawn

can you fill out your profile a bit more? How are you seeing fuel trims? Pocketlogger? If so, how does your a/f read? Knock? timing advance? Give us a little more info.

BTW for the most part, only your lo settings will affect trims. You will need to see what is going on under WOT to set the hi.

 

[nine5raptor]

Originally posted by sqhopeful
I too am a tuning newb, i found this on a search to try an find out what the fuel trims should look like.......

if you have 550's and a safc on zero across the board, how are you lean?

The 2g mas is calibrated leaner. Usually it is about 20% leaner, but they are all different (tolerancing).

 

[beastlytalon]

i would guess they dont make sense because of this statement from a topic on loggers...

All kinds of issues here.

First of all, that is one point of a log, at 2500 rpm and 100% throttle. Not too useful.

If you want to log for WOT tuning, log from whenever boost comes on until redline in second, third, or fourth gear. LOG ONLY RPM, KNOCK, AND TIMING unless you have a good reason to log other stuff.

If you want to log for idle or cruise, log the rpm, tps, and all the fuel trims (including O2 trim). There is no reason to save all that other crap, it just slows down the flow of the good information.

What are you using for injectors, air metering (hacked, unhacked, etc), what turbo, what boost?

Give us information about your setup, and take a better log, and we can give you a hand.


....Kyle T.
93 TSi AWD "TURBO4"
14b - 12.8 @ 108

aren't fuel trims kinda useless at wot?

 

[overdose]

So what are the optimal fuel trims for best mileage/performance? 110% low/mid and 90% WOT ?

 

[sqhopeful]

the trims tell what is going on during part. throttle or cruise. ideally....100%, ie no ecu adjustment. For WOT tune for knock and timing.

 

[Bohrn]

Kyle, I have no reason to doubt you, but why not log O2 voltage and inj pw along with knock, timing and rpm??

I have been doing this as well, and sometimes throttle position.

I like to cross reference these.

 

[sqhopeful]

i was messing with my lo throttle setting today, as today was the first day my datalogger and I got to know each other. Intially, my all mof my fuel trims were high
L:138%!
M:122%
H:110%

AT Idle I can add fuel and watch the low trim dip below 100%. But as soon as I start driving it's back to 138%. I put in alot more fuel on the lothrottle setting than i had before, as well as some WOT tuning (added a lil' fuel) and now my trim are...

L:135%
M:118%
H:98%

Mid way thru tuning my 02 trim wouls cycle between 98 and 105%. Now the o2 trim is in the 80%'s. I so I think I should take some of that fuel away. either way the low and mid trims did not budge.

any thoughts? should I be resetting my ecu when messing with this stuff?

 

[nine5raptor]

A few things:
You have to be in a certain rpm range for the mid. Drive around (say on the highway) for about 10mins after making a change and wait for it to update. I don't know how long it will take, but I know the 1gs are pretty slow about updating.

Also, make sure you are changing your low settings on the afc. Only these will affect the trims.

The 02 trims are on a different scale. They are about 4x the trim scale. i.e. low 105% 02 120% or so.

With the hacked mas, wacky settings to get the trims under control is expected.

Only adjust the hi trims to tune for timing/knock (a little knock is ok).

 

[Bohrn]

one point to add to this.

the low trims are only at low airflow. On the hiway, you will be flowing too much air for low trims.

Go on some back roads without alot of traffic and lights etc.

Get in 3rd gear and go 2, 3 and just under 4 grand.

Stay at each RPM for a while. Watch the O2 trim, and low fuel trim. When the best-fit line on the O2 trim is a little above 100% for each RPM, and all seems good, drive it for a few days and monitor it again.

Do the idle for the 1000rpm setting on low on your safc. Same thing, but at idle and sitting in your driveway. O2 trim cycling around 100% or a bit higher and trim around 125%, all is well. I get better mileage at this setting than at 100% You might not be able to get the trim to move the first day or so, but get your O2 trim cycling nicely at just over 100% and it will sort itself out.

best of luck, and my instructions are based on my well ported maf and my particular vehicle.

 

[sqhopeful]

thanks fella's,

I think I will take away some fuel I gave it today, and get the o2 trim to look right again. When i read in several places that the trims may take awhile to update, I thought like minutes! I will take it to work again tomorrow and monitor the trims on friday again

thanks again,
KC

 

[sqhopeful]

let me hijack this thread again......

one more trim question. I got my trims to look this

Hi: 92, a little rich but I am confident I can get that to 100
Mid: 101
Lo: 118

My questions is this. SOMETIMES when I come to a stop and idle, my lo trim will jump back up 138% although my o2 trim is right on cycling between 105-115'ish, what's up with that?

 

[EuroGSTSpyder]

hehehe..tuning is a bi***..I have trouble too I havent even set my 660s in yet since I wanna test tune first alittle..so I keep boost down for now.

However..I looked at my logger and found that my STFT is bouncing up and down when I dirve and the LTFT is prtty much stuck at 117% wich is way to high.So with stock inj, Big16G, FMIC, 3" exhaustsystem,7grade plugs, magnacore wires, K&N filter, 2 3/4 intake pipe, MBC set at 12-13 psi....
Where should I begin to tune the trims?Seems odd to be running so rich with stock inj ..but O2 seems ok....at wot they stay at .94 tops... My egt isnt in the car yet.. :-(
I can go get a log for you guys in a few days(working my ass off**)
and show ya how it looks..?Just thought I ask a base question.

If anyone is willing to help me off of the board with my tuning I would really appreciate it since I am all alone with SAFC here on DSMs :-((

 

[nine5raptor]

a ltft of 117% (doesn't make sense since you have a 2g and the fuel trims on 2gs are near to 0, not 100) means you are lean and the computer is ADDING 17% more fuel to get it inline. You are thinking about it backwards.

 

[EuroGSTSpyder]

Originally posted by nine5raptor
a ltft of 117% (doesn't make sense since you have a 2g and the fuel trims on 2gs are near to 0, not 100) means you are lean and the computer is ADDING 17% more fuel to get it inline. You are thinking about it backwards.

sorry there was one too many 1 there..it says 17% of course..not 117 ;-)

Yes I realized my mistake now.If the logger reads on the positive side I am short of fuel and the ECU is adding fuel.
So since my logger says 17% on the FT I am running lean and should richen up a little ..right?Still need to tune my FTs in so I can start to tune it in later....Maybe will wait til my 660's ar ein though..might as well do it right from the start....

However..mu clutch just started to go bad so I am ordering a new ACT2600 and will install during winter since the season for topcars are out now here in Sweden..have some major work to do during winter