What do you guys set this setting to?

To the lag time the manufacturer of the injector says? or do you just experiment with it?

I have SARD 680cc injectors, number on the injector is: ND 195500- 0830

I found this page, here it says .96ms lag time.

I have the IOT set to .125ms, i have got a pretty good idling, and afr is ok, but the afr does change every now and then, sometimes it will idle with 14.5-6, and at the next red light it will be 13.5... and so on...

Do i have this setting wrong? And if i ad a bigger number to IOT, do i need to subtract the same from TOG ?

Thanks
Asim

The "lag time" should correspond to the "Minimum Injector On-time", not IOT.

IOT and TOG are simply setting up a basic straight-line relationship between engine load (MAP) and injector pulsewidth. Nothing more, nothing less. Every thing else having to do with fuel delivery is based on this underlying relationship.

If you remember your algebra, the equation
y=mx+b
defines a line where m is the slope of the line, and b is the offset, or zero crossing. For us,

IOT = b (offset)
TOG = m (slope)
and
y=injector PW
x=MAP (load)

Usually I try to set IOT and TOG so the the engine runs reasonably well (i.e, not pig rich, not lean) across a range of loads for a given rpm.

Obviously first you have to get it to run at all, so you can start off with the suggestions that the wizard gives you. I prefer to set IOT and TOG with the VE table zeroed out, so if the wizard trys to put values in the VE table, set them all to zero.

Getting the engine to idle will mostly be an exercise in manipulating IOT, since it has the most influence at low MAP values.

Once you have it running well enough to drive around the block, take it to a SAFE, NEARBY place and check the TOG setting. You can do this by holding the RPM at a reasonable value, say 3000rpm, and dragging the brakes while slowly increasing throttle to maintain RPM. Don't take this to extremes, obviously - you don't want to be running 10psi of boost while doing this. Just take it to ~100kpa or maybe a little higher - that should suffice. As you start getting IOT and TOG dialed in, you can go a bit higher, but use caution, obviously.

If you start to notice that you are going lean as you increase throttle, then increase the TOG. If you go rich with increasing throttle, decrease the TOG. Don't get too hung up on what these numbers come out to, so long as your AFRs stay close to the desired values throughout the load range.

You'll probably have to mess with this for a while, but IOT and TOG are arguably THE most important settings for the TEC. The rest of your tuning will be much easier if you first spend some time getting these right.

The main exception to this rule is the Min Injector On-Time - this setting will prevent the TEC from using a pulsewidth that is less that the min on-time. For instance, if the IOT/TOG equation is asking for .5mS PW, and the min on-time is set to 1mS, then the TEC will use 1ms instead. So, if you start noticing that changing IOT is having no effect, check to see if your pulsewidths are at or near the min on-time. If they are, then set IOT to the setting that gets as close as possible to the min on-time at idle.

im gonna stickey this for now

TimZ,

thanks for your input.

The car is running ok, and has been for about a year, but i still havent had the time to take it on the dyno for completion of the map.

The thing is, i REALLY enjoy doing things myself, the more i can do the better i feel

I had the map pretty much ready, but i was having lots of trouble with idle AFR, it would not idle leaner than 11.5 - 12

And when i altered the IOT to .125ms it changed a whole lot, idle AFR is perfect, but it added fuel all over the midrange map, so i had to do take of fuel to get the AFR back to normal.

The thing is, i already have done lots of corrections in the VE table, if i alter the IOT / TOG, then it will affect all af the map.

Should i start all over? or just work with what i got?

If any of you are interested and have wintec2 on your computer, here is a link to the map i currently have, any feedback is most appreciated

http://home.no/mrhappy/tec2/

Cheers
Asim

So is the IOT the only thing that has changed from before? What was it set to before?

I noticed that you currently have your min on-time set to zero. You should set that to correspond to the "lag time" you mentioned above. That will help prevent erratic behavior in high vacuum situations. Approximately what is your MAP at idle? Also, how much boost do you run?

That is correct, the only change i made was to the IOT. Before it was 0ms, and i changed it to .125

I now understand the difference between lagtime and IOT.
I will set the Min on-time to what the manufacturer of the injectors advice.

Map at idle is about 60kpa i think, not 100% sure, but will check later today.

Currently im running 1.6bar boost...

Okay - more questions...
It seems like you have some pretty large swings in your VE table, like +/- 35%. This suggests that maybe your IOT/TOG curve is not steep enough, since you are having to add a lot of fuel at high load, and take out a lot of fuel at low loads. Do you have a rising rate FPR or something that might explain the wide variations?

I can make some simple suggestions to fix your current table and leave it at that, but it seems like maybe it would be a good idea to get a better fit with the underlying IOT/TOG curve first.

Do you have a site where I could upload a suggested calibration?

Hi again TimZ

First of all, just let me say i really appreciate all your input I think i have got more sensible info from you and a few other forums, than anyone in Norway

I also think that the IOT/TOG curve is not perfect, but i just got used to changing the VE table that much. And it is quite hard to get the fuelling correct when there are so big swings...

And i do have a adjustable FPR, but im not sure if it is raising rate. When i had the car on the dyno before i built this engine, we did not see any big difference in fuel pressure, at idle it is about 3.5bar, and on boost it is about 4-4.5bar.

Could you please tell me the fix for the current table?
And if you do have the time, make the new IOT/TOG curve.

You could send the calibration files to my email:
asim . gondal (at) gmail . com

And i will upload them so other people also can have a look

Cheers
Asim

Web-Tunez by Timz... I love it... will you do me next?

OP: Timz is a knowledgable guy but I don't think he or anyone else could tune a car over the web, flash tunes excluded. I think you are best served reading his advice on how to set up TOG and IOT and then tune your VE with you WBO2 (you do have one yes?)

FWIW, I understand you like to do things yourself... perhaps to start you go to a skilled tuner with a dyno and get it done safely. I would hate to see you blow a motor over this. There will be plenty of fine tuning, drivability, cold start, accell stuff, for you to play with, don't worry.

hehe...

I hear you buddy... i only need some pointers to get things rolling.

Im still running a very safe ignition / fuel map... and the car is actually very quick. Before i built this engine i had it on the dyno, and it made 460hp / 550nm at the wheels... but unfortunately it spun a rod bearing due to a crack in the crank journal.... and we had only started to get the fuelling map ok... didnt even touch the ignition map...

I do have a wideband

Thanks
Asim

Not tuning per se - I was only going to suggest new VE table settings that would keep Asim's injector pulsewidths at medium and high loads the same as they were before modifying IOT, on the assumption that the old VE table worked okay, save for the idle mixtures. It's just math.

Taking the same logic a step further, my next suggestion was to do this same exercise, execpt with the goal of getting a better fit with the IOT/TOG curves. A bit of a pain in the ass, but still do-able.

I would not advocate trying to tweak for more performance over the web, and agree that this would not be a good idea. The idea here was to come up with a table that works like the old one did under load, and retains the improved idle characteristics of the updated IOT setting. Nothing more.

The other point is that if Asim wants to start over, I'd suggest going with a bit steeper IOT/TOG curve, just to minimze the VE table excursions, and leave more headroom for actual tuning, rather than just compensating for the baseline being off.

Maybe that explanation makes more sense? Sorry if I gave the wrong impression.

Hi Asim,

I am sorry that you are not satisfied with the support we have been giving you. I have answered your questions as good as i could. Maybe my pedagogic skills is not good enough. But if you have any questions, do not hesitate to call, you have our numbers.

Geir H at Bjornstad Bil.