Injector Constant - Best Way to Tune?

[GHuggins]

I know this has been touched on in the past and Mike has done some pretty decent write ups on a lot of the lnf stuff, but I'm just curious of the best all around route to take on this.

In other words is it better to dial in the injector constant off of fuel trims during regular driving or is it better to dial in the injection constant for wot then use the MAF transfer curve to dial in drive ability areas... I did it off of idling fuel trims and everywhere during wot is extremely lean. If I dial it in more for wot I'll have to take out about 15 to 20 percent in the regular driving and idle areas. OR is it just better off to leave it alone and use the MAF curve and MAF correction table to dial it into target?

All opinions and knowledge welcome.
Thanks,
Greg

[MikeM173]

I never recommended either spots. I recommend changing Injector Constant based off of certain cells in the logs. Idle and WOT in my opinion are not the spots to tune off of.

[T-Man]

I do things a little differently. I use the injector constant to make the large scale adjustment based off of where the LTFT settles. I then reflash/unplug the EVAP connector and run strictly based off of STFT and fine tune with the MAF Correction table. I don't like to adjust via the MAF Frequency due to my own experiences.

STFT only for me. No LTFT input

[GHuggins]

Mike, it would make more sense to get an average at or around 2000 rpms while being held - takes a lot of things out of the equation. AND you could even get an overall average just from light driving to get the average with engine load applied...

T-Man, have you seen anything weird from scaling the MAF itself? Just wondering why you don't like changing it....

My issue isn't really with wot up high (it's dang near perfect target). My issue is with leaning out during initial turbo spoil up... This is using a "fresh" GM OE tune after flashing back with MDI and re-downloading and starting over too Mike. This did seem to fix a lot of "phantom" fine one minute then way out in left field issues I was having....

[MikeM173]

Let's try and correct what I meant.

The areas I adjust to are around the 2000-3000rpm range and the 20-80% load range. Why? Because this is where your neutral driving happens and it is a good average spot.

I start with Injecto Constant because it is a broad way of tuning fuel. Think of it like school.

In Elementary, you are learning the basics.

In middle school you are learning more details but not too much.

In high school you are learning more details but on different subjects.

In college you are learning a specific area you want to focus on and getting down to details.

In the job you learn all of the fine details you need to know.



Tuning a car is much like the same. Start with something that is not specific and has an affect on everything. Injector Constant. Then focus on something that is more detailed but is still broad. MAF Frequency. Then focus on the fine details. MAF Correction (it focus's on a specific cell).

This is just my way.

[PSYKOSTEVO]

I do things a little differently. I use the injector constant to make the large scale adjustment based off of where the LTFT settles. I then reflash/unplug the EVAP connector and run strictly based off of STFT and fine tune with the MAF Correction table. I don't like to adjust via the MAF Frequency due to my own experiences.

STFT only for me. No LTFT input

STFT vs MAF Correction works really well.

[T-Man]

T-Man, have you seen anything weird from scaling the MAF itself? Just wondering why you don't like changing it....

Yes, in my experience, it shifts the load calculations and negatively impacts other load based tables (again, in my experience). Unless you've changed the MAF housing size or moved it from the factory location, I personally don't recommend any adjustments within that table. This is based strictly off of my own personal experience with my two cars and 3 other cars that I've done.

STFT vs MAF Correction works really well.

Yes sir, it sure does. Not only that but for me, running STFT input only helped to smooth things out greatly. For me, I've found that my fueling stays much tighter as well, regardless of the massive swings in ambient temp that we love to enjoy here in Phoenix (outside of WOT of course)

[GHuggins]

T-Man, if your not tuning the MAF curve... How do you dial in your fueling to the best possible. Seems like .8's or 1.1's in the MAF correction table would do the same thing as far as torque calculations goes... That is if the OS is still using the MAF correction table for calculations? I've run into a problem with the engine having a "set" 3 degree timing advance at 3000 to 4000 rpms with a "ghost" knock retard of 3 to 4 degrees that I can not get rid of no matter the lambda or timing put into it. NO where in the tune do I see how it can command 3 degrees of timing... The injector constant is OE right now. May just have to take 10 percent out and start over from there?

Attaching current tune and log with timing "stall"...

[T-Man]

T-Man, if your not tuning the MAF curve... How do you dial in your fueling to the best possible. Seems like .8's or 1.1's in the MAF correction table would do the same thing as far as torque calculations goes... That is if the OS is still using the MAF correction table for calculations?

As I said, the bulk of the fuel shift (due to running ethanol) is taken care of via the injector constant. I utilize the final/settled LTFT percentage after a good. Once I get my STFTs where I like them to be, I further fine tune using the MAF Correction table. The way I understand it (could very well be wrong too), ECU uses a blend of the MAF Frequency and MAF correction for final MAF based fueling. However, only the Frequency table is used (along with other inputs) in load/torque calculations. Again, could very well be wrong. That's just how I understand it.

When I was using the MAF frequency table for the bulk of the fuel shift and then fine tuning with the MAF Correction as most write-ups indicate to do, my calculated load was much, much higher and I found that the car became very touchy with regard to the throttle input.

I've run into a problem with the engine having a "set" 3 degree timing advance at 3000 to 4000 rpms with a "ghost" knock retard of 3 to 4 degrees that I can not get rid of no matter the lambda or timing put into it. NO where in the tune do I see how it can command 3 degrees of timing... The injector constant is OE right now. May just have to take 10 percent out and start over from there?

Attaching current tune and log with timing "stall"...

I can't see your logs or tune but this sounds like an optimum spark issue to me. Do you have one spark table for all MS tables? Same for optimum spark tables, one table for all 4?

[GHuggins]

As I said, the bulk of the fuel shift (due to running ethanol) is taken care of via the injector constant. I utilize the final/settled LTFT percentage after a good. Once I get my STFTs where I like them to be, I further fine tune using the MAF Correction table. The way I understand it (could very well be wrong too), ECU uses a blend of the MAF Frequency and MAF correction for final MAF based fueling. However, only the Frequency table is used (along with other inputs) in load/torque calculations. Again, could very well be wrong. That's just how I understand it.

When I was using the MAF frequency table for the bulk of the fuel shift and then fine tuning with the MAF Correction as most write-ups indicate to do, my calculated load was much, much higher and I found that the car became very touchy with regard to the throttle input.




I can't see your logs or tune but this sounds like an optimum spark issue to me. Do you have one spark table for all MS tables? Same for optimum spark tables, one table for all 4?

So these platforms just use the base MAF curve for torque calculations? That's interesting... Yes I set all 4 of the spark tables the same using the max intake and max exhaust cam tables as the tables I used. I've added timing and taken timing out - still getting false knock and for what ever reason it was only running on 3 degrees timing here. My op timing tables are smoothed along with the main timing tables, but have had roughly 3 degrees added to them. I tried Mike's method for setting these up, but didn't have good results - would hit negative timing before ever hitting the rev limiter and was also causing idle issues. I've gotten the idle problems on this car fixed "for now "....

I finally took things to extremes and killed the max amount of knock retard to -3 and got it to maintain 10 degrees timing advance, but the problem is still there. Now really wondering what's going on? I made another post about this issue - hitting a wall at 3200rpms... I just can't figure this one out. As many vehicles as I've tuned and this one's really making me feel stupid to say the least For anyone reading this, Gen 5's are much easier

Only thing I could think of on the way home tonight was cam tables during wot causing a "choke" condition on the turbo - but grasping here?

[cobaltssoverbooster]

the maf correction is a linear data calibration plot. in order to guarantee its accuracy on a 3d plane the maf base table is included as a final multiplier.
the maf correction is the base of the maf sensor data and the base table is a modifier to take care of inconsistencies that cannot be filtered under the standard correction process. that is why the maf base table is defaulted to 1 and then corrected after the maf correction has been calibrated.

both tables are for modeling and prediction as long as the value in the base table is anything other than a value of 1.

[T-Man]

the maf correction is a linear data calibration plot. in order to guarantee its accuracy on a 3d plane the maf base table is included as a final multiplier.
the maf correction is the base of the maf sensor data and the base table is a modifier to take care of inconsistencies that cannot be filtered under the standard correction process. that is why the maf base table is defaulted to 1 and then corrected after the maf correction has been calibrated.

both tables are for modeling and prediction as long as the value in the base table is anything other than a value of 1.

Thanks for further clarification CSSOB.

Based on your description, I still stand by my original statement. Unless you've changed the MAF housing size or moved it from the factory location, I personally don't recommend any adjustments within that table. There's better ways available to us now, IMHO.

[GHuggins]

This is my current Optimal and Main Spark tables... Anything obvious with these? I noticed when it hits the spot where it's pulling timing, it also shows desired DC dropping to 90% then when problem is gone, DC goes back to 100%. Just something I noticed in the logs... I set the MAF curve back to stock and used the injector control to dial in fueling to best "all around" as you and Mike have said to do. Seemed better, but bad power and torque dip still there...

[MikeM173]

Steelmesh, the LNF is totally different then what you are talking about, just so you know.

[GHuggins]

The internet told me to do it this way, I am attempting to calibrate the 1.4T with Bosch 42 lb Green Giants:

If you don't have injector table for flow rate vs pressure, use an online calc to estimate flow at different points on your flow vs. pressure table and interpolate. Take it for a drive and see where the trims go, my case was -20% rich. Next adjust your the injector offset vs. pressure (vs. voltage). I ended up taking -23% out of this offset vs pressure vs volts table across the board, LTFT are -9 near idle and -2 in cruise range. I made a slight adjustment to the MAF table up high in WOT out of cruise.

Also, as I tested, "tricking" the injector flow rate table will impact your vehicles MPG calcs. I am certain a tuner could cook the numbers and make it seem like your MPG calc has increased when it actually didn't.

LNF is direct injected... Completely different

[MikeM173]

GHuggins, send me your current tune and log for that tune and I'll take a look at it later tonight and let you know what I think.

[cobaltssoverbooster]

LNF is direct injected... Completely different

you need to either make a custom flow bench and perform calculations yourself or send them out and have them flow tested or else the information is not going to be very accurate.
you can get close but the tuning steps to lock them in after the fact is ridiculously lengthy.
i highly recommend the second option.
if you need help start a new thread on 1.4t fueling.

[GHuggins]

you need to either make a custom flow bench and perform calculations yourself or send them out and have them flow tested or else the information is not going to be very accurate.
you can get close but the tuning steps to lock them in after the fact is ridiculously lengthy.
i highly recommend the second option.
if you need help start a new thread on 1.4t fueling.

Now I'm confused??? Thread was originally meant to see how people prefer to approach tuning for fuel corrections. This isn't the first time I've seen people mess with the injector constants. In fact it's how some people are even addressing MAF limits built into the gen 5's....

Steelmesh was referring to a low pressure fuel system, which I will only ever recommend ID's for replacements.... OR possibly you meant to quote steelmesh instead of me??? That actually makes more sense

Mike, I've obviously got your cell number, but never got your email to send you the info... Car drove really smooth when done. Way better fuel trims and air fuel ratio's then when it showed up. Still had false knock, but was putting out the commanded timing and finally got that "choke rpm stall" out of it that it had showed up with. Thanks again for your help... Would still appreciate you looking things over. Always willing to learn more with something I haven't had the luxury of messing with...

[cobaltssoverbooster]

I missed the quote I wanted to source.

I just know someone will read this thinking it's all di then start changing the constants as if it were a multiport. Just trying to keep information separated by fuel system style so people don't go blowing their engines.

If your ok with cross contamination that's fine, it's your thread. I won't comment any further.

[GHuggins]

I missed the quote I wanted to source.

I just know someone will read this thinking it's all di then start changing the constants as if it were a multiport. Just trying to keep information separated by fuel system style so people don't go blowing their engines.

If your ok with cross contamination that's fine, it's your thread. I won't comment any further.

Your comments are always welcome. That's why I stated you most likely meant to quote the other post Also why I posted this is in regards to DI motors, not the low pressure fuel system motors Didn't mean any offense by it and apologize if you took it as such....