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Road tuning fuel trim question

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28K views 28 replies 9 participants last post by  flipsx3  
#1 ·
I'm currently trying to learn how to road tune fuel trim. Here is my set up:

ITR head
IPS K2 cams
RBC i/m
ITR t/b
Karcepts CAI
Prototype velocity stack
k24 block
TSX rods and pistons
Hytech 4-2-1 header
3" exhaust

I started to practice on the low cam at 0 degrees. 13:1 a/f ratio is what I was shooting for. I was able to get the fuel curve pretty flat. However, while I was tuning I noticed that at 5000 rpm and WOT (-0.2/psi) I had to go as high as 2840 units of fuel to get the a/f ratio I wanted in that area. Is this normal? Also, is 13:1 a/f ratio too rich to be shooting for? Thanks.
 
#2 ·
That does seem a little high. I'm between 1900-2000 on a k20a. However you have ips cams, k24, rbc, hytech header, etc. So that may be why you need so much fuel. Some questions would be :

1 - How long did you datalog? I've found you need as many datapoints as possible to get an accurate a/f. I'll generally do multiple pulls and look at the combined data. For road tuning, I've found a 20-mile loop that I drive that give me enough terrain to get good coverage of all the cells on the fuel table.

2 - What size injectors are you running?

I've been shooting for 13:1 as well. I've heard numerous people say somewhere between 12.9-13.2 . I'd rather go a little rich for reliability. Although I tune part throttle for 14.7:1 and mid throttle for 13.8:1.
 
#3 ·
i did about 6 full-throttle data logs to get to the units of fuel i am at now.

i forgot to mention i am running 440 injectors.

also, i moved on to the 10 degree cam angle and it needed quite a bit of fuel at 5000 rpm as well.
 
#4 ·
kommon, how do you personally go about tuning your part-throttle and at idle? i noticed that when i get the motor to run 14.7:1 a/f ratio at idle on open loop it needs to adjust between -4% and -7% short-term fuel trim on close loop.
 
#11 ·
For part throttle, I do the following :

1 - Lock cam angle
2 - Set ecu to open loop, and disable obd2, set vtec to 6500
3 - drive & datalog. I don't start logging until coolant temp reaches 175deg
4 - I drive around for at least 30mins. I've found a route in my area that has stop/go, hills, highway, etc. So I get about 20-25miles and I can cover the entire fuel map.
5 - Adjust based on info from #4.
6 - Repeat #4 and verify data. If it looks good, move onto the next cam angle and go back to #1.

I haven't spent any real time tuning vtec part throttle. I tune the high load maps by just driving around, and whenever I get to a safe strip of road, I wind out 3rd gear. However its really best to do this on a dyno because a speeding ticket costs more than dyno time...

I don't stress too much about idle. I just try to get close so that closed loop doesn't have to adjust much.

You will also want to make sure that our gear compensation is correct before doing any of this.
 
#5 ·
how is this new setup compared to the old one?
 
M
#6 ·
I have a comparable setup and have values above around 3000 at 5k WOT to say at 13.2:1. I'm fully tuned my car myself. I have values as high as 3300 at WOT at 7600RPM. That doesn't sounds unreasonable. My mods for comparision:

K20a2 Fully Built Ported Crower Head w/ BC Stage 2 Cams, Flat top Valves, Ported IM w/ Hondata Gasket, RDX 410cc injectors.
K24a4 Block w/TSX Rods and Pistons, Buddy Club Race Header, Comptech Catless Exhaust, and Injen CAI

FYI... If you are running those values with stock injectors you are probably maxxing them out. Check you injector duty cycle ASAP.
 
#8 ·
thanks for the reply macho. yeah i'm running 440 rc injectors. the duty cycle was around 40% at that particular point.

do you have any advice on tuning idle and partcial throttle that you would like to share?
 
#13 ·
If you click the parameters button in kmanager, you will see the "Gear Comp" button. This lets you adjust ignition, fuel, etc. based on what gear you are in. I ended up making small adjustments to fuel depending on what gear I'm in.
 
#14 ·
i finally got around to messing with the 40 and 50 degree low cam angles, and i've run into a problem. at WOT, around 2000 rpm i'm running really lean and around 2500 rpm i'm running rich. so now i have these fuel maps with huge peaks and valleys (about 1000 units of fuel difference), and i'm not even done adjusting yet! according to the data log i could probably use about 7% more fuel at 2000 rpm and -3% at 2500 rpm.

i have attached a WOT data log run for the 50 degree cam angle and the cal that i have so far. if someone could take a look at them and tell me whether it's normal or not, it would be much appreciated. and if it is not normal, what am i doing wrong.

thanks
 

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#15 ·
nowheres on your low cam fuel map should you need 50 degree cam advance. thats probably why. your crusing part of your fuel map is columns 2-7. and you should have the whole thing set to 30 for your setup imo. make your crusing part of the map say all 30's. do a 30 minute datalog all crusing in open loop. try and make the car touch all areas of the crusing part of the map a few times or more. load the datalog into Kautofuel if you wish , or use lambda overlay in Kmanager. add or take away what it says. than do it again. and again. till its perfect. for WOT , id start setting your cam advance in columns 8-10 to 30 , from 0rpm to redline. you really need a dyno for this part to get what you can and find out which cam angle gets you the most power where.
 
#16 ·
thanks for the response cranny. i've already done basically everything that you posted. now i am at this point.

i'm not to the "tuning for power" part just yet. i'm just basically starting from scratch and going through each cam angle and getting the a/f curves as flat as possible.

as for the partial throttle portion, i've done a whole bunch of 30-45 minute data logs with the different cam angles. and using kautofuel, i have been able to get the a/f's for those down pretty good. it seems that the motor likes 25 degrees the most for cruse.

but back to my question earlier. i've been able to get my 0-30 degree WOT fuel curves nice and flat using lambda overlay. 0-30 are really good at this point. it's the 40 and 50 fuel maps that i am concerned with, mainly between 2000 and 3000 rpm. the huge peak in the fuel map is what i want to know about. is it normal???

did you take a look at the cal and data log?
 
#17 ·
You don't have enough data points to accurately set the a/f at wot. Your datalog only showed 6 seconds.

You also want to make sure that your car is properly warmed up 175+ ect.

Don't worry about wot at less than 3k rpms. Just keep the curves smooth. Realistically you really shouldn't ever be there so hard to get good data.

I typically do multiple 3rd gear pulls on the same datalog to get more datapoints for wot tuning.
 
#18 ·
thanks for chiming in kommon. yeah, i understand the data log is too short. i just did a pull to show what was going on while keeping the file small.

ect was 192.4 on that particular data log.

so you saw the fuel curve? did you take a look at the map also?? everything is nice and flat after 3000 rpm (i shot for 13.2:1). it's what is going on before that is what i was worried about. but if your saying not to worry about tuning in that range (2000-3000) i am still curious of the reason why it's doing what it's doing.
 
#19 ·
by glancing at the cal file the fuel maps are really screwed up.

your cam angles look off so does your fuel..maybe u should ask someone for a tune who has a similar setup..:up:
 
#20 ·
by "screwed up" what do you mean? what part?? all of the fuel maps??? the 0-30 maps are good.

don't worry about everything else on the cal because none of it is coherent. i just pasted the 40 and 50 degree maps on this cal so that someone could take a look at them (just the fuel maps nothing else) and see what they think. i'm still locking in each cam angle and tuning fuel at WOT. i haven't gotten to the building a composite cam angle map part yet.

does anyone have any insight on what is going on with my 50 degree cam angle fuel map???
 
#21 ·
this being a k24 with a type R head the CAL has a lot less fuel in areas that suppose to have a lot more fuel. Those headers like fuel and where it suppose to have a lot of fuel is missing.
 
#22 ·
exactly, that is what i was getting at. there are points where it is showing too rich (12.XX:1) and that is where all the fuel has been taken out. it looks weird doesn't it?
 
#23 ·
haha. the stock tsx cal is pretty horrible starting point. can't belive the tsx is tuned this way lol..:up: maybe its the shitty header setup on the stock tsx..

I would aim for a fuel ratio of around 12:60..this engines like to run rich.
 
#25 ·
like i said , its simply too low of revs to utilize that much cam advance. theres no sense on trying to guess as far as WOT goes what cam angle is gonna be the best for what certain rpm. cause without a dyno , you cant tell anyways.

if i were you , id run in columns 8-10 , 30 degrees of cam the whole way. o rpm to redline. from my experience of tuning k24/k20 engines , they dont like alot of cam. they dont need it , or should i say cant use it efficiently. last setup i played with , was k24/20 engine , DC race header , no cat of course , 2.5" TIC exhaust , stock A2 cams , stock A3 intake , short ram intake(Kseries do not like at all). his engine liked 30 degrees of cam. any more would lose , any less would lose. he dynoed 210 whp. i forget torque.

of course these are just my suggestions. dont bother tuning 40-50 cam WOT in low cam map. pointless with your setup buddy.
 
#26 ·
cranny said:
of course these are just my suggestions. dont bother tuning 40-50 cam WOT in low cam map. pointless with your setup buddy.
Click to expand...
thanks for the input cranny. i agree with what you said. it all makes sense now.

after using theta dyno i saw that the 30 cam angle was the best low cam for WOT. i am currently running 30 degrees in colums 8-10, 0rpm to vtec.
 
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