Hey,
I have done a little tuning in the past using tunerpro and data logging with Datamaster.
my question is that with my previous 22 lbs stock injectors I had to set the constant at 25 lbs to get the BLMs close to 128 and then I adjusted the maf tables followed by wideband wot tuning in temp vs pe and rpm vs pe. The commanded rate and actual wideband results were not consistent. I’m just wondering if this is because of the injector constant difference.

skip forward a year and I replaced my injectors with 24 lb Bosch 3’s and my injector constant is now set at 27.75 to get the BLMs in the right range.
Is there a better way? My maf tables would need some serious adjusting if I would set the constant to what the injectors are rated at.

thanks for any input

 

It's ALWAYS good (when asking tuning questions) to list your mods. I see -- by your profile -- that you have a bigger TB. That alone would require changes to your MAF tables. I have the same (24lb SVO) injectors that you are using. My BIN is set to 25.5 lbs...which is what they should measure in our STOCK fuel rails. The pressure you are running would make a difference.

My MAF tables were significantly altered. I am running a 383 with stock MAF...but expanded everything else...in the intake tract.

IIRC, I think percentage fuel added is more based on MAF tables than injector size...which means you can "cheat" like you did...but with some potential consequences. For example, you probably are running lean during warm-up....since your car THINKS it has big injectors....and warm-up fueling is taken as a percentage. Accordingly, the same could be true at WOT. Since it THINKS the injectors are smaller than they are, your PW would be shorter-than-actual-requirement. Inconsistent WOT reading make me wonder if you have a worn TB assembly...or TB sensor...or mal-adjustment. I also wonder if your FP is high? If so, those injectors can/will push more fuel than their FORD rating.

If you don't have it, these should be your values for Injector Pulse Width Correction vs Battery Voltage...something else that can affect size/performance....


0.00
0.00
0.00
30.52
152.59
305.18
427.25
518.81 (14.4V)
701.91 (12.8V)
946.06 (11.2V)
1251.24
1770.04
3387.50
7751.57
610.36
610.36
610.36


I filled in the primary 3 rows that should be in use for the nominal voltage being run. I use TunerPro myself. I assume the other rows should line up accordingly...if you cut/paste.

 

Thanks for the info, I’ll check the values tonight to compare. What I mean by inconsistent is that my calculated command afr is greatly different from what the wideband is saying. It’s running great, but was wondering if changing the injector constant so much is skewing my other values that I have not adjusted yet.
With the injector constant set at 27.75 before touching the maf tables I was running on avg 127 blm and moving up to 134 on the last table . This was the closest avg I could get before I made changes to the maf table as I didn’t want to drastically change them and the scalers.
Mods include: long tube headers
52 throttle body
opened up plenum
3.54 Dana 44
accel distributor/coil
air pump delete
cam (unknown)
24 lb Bosch 3
KN
1.6 RR
clutch (unknown) grabs hard

 

[QUOTE=Billygoatkid;1599965450]Thanks for the info, I’ll check the values tonight to compare. What I mean by inconsistent is that my calculated command afr is greatly different from what the wideband is saying. It’s running great, but was wondering if changing the injector constant so much is skewing my other values that I have not adjusted yet.
With the injector constant set at 27.75 before touching the maf tables I was running on avg 127 blm and moving up to 134 on the last table . This was the closest avg I could get before I made changes to the maf table as I didn’t want to drastically change them and the scalers.

I understand what you are saying but Like GREGGPENN said, incorrect voltage offsets for your particular injectors can greatly affect your MAF tables and make tuning much harder. It is the dead band, time it takes for the injector to open which is added to the PW to correct for that time. It will affect every table that has a PW value in it such as AE and PE. And since it has more effect at small PW, increasing the injector constant it will probably make it lean at WOT.

 

Thank you!
ok so what should I be expecting by putting these values in? Should I be protecting a lean condition before data logging? I’m at work right now but will check when I get home what the differences are.
obviously the numbers you gave me are different than the stick bin.

 

Hey
Here are my values: so I notice the ones you posted are much lower. What am I to expect on the next data log run?

 

Did you have a link to your injectors? After rereading your OP, I made the assumption you bought 24lb "SVOs"...which were originally intended for Ford SVO cars. And, they run at a lower FP. It's been years since Jon (FIC) provided the link to the offsets ... and ... I hope I entered them correctly. Somewhere WAAAAAY back in emails I might have the link he originally provided me.

Point is (after seeing where yours are currently set), I'd want to make sure (if possible) that you have the correct voltage offsets. For one thing, I think there may be two 24lb Bosch III options?

That said, I agree with your thinking that lowering those table values might put you further "off" than you are. As previously stated, I had to significantly increase my MAF table values when I used the 24 B3 SVO's and installed them in a 383.

To make sure I didn't so anything "crazy", I monitored each BIN change for short around-the-block trips (or even idle/off-idle measurements) before doing anything "rash". I'm saying you're not going to hurt it if you don't going WOT until you are happy with "driveability" scans/tuning. Once you get "driveablility" set, WOT should be a percentage of what you tuned. And, can be verified with a dyno run at your local roller-dyno shop. (They use sniffers in the exhaust -- if you don't have an extra O2 bung for WB measurement....which is what I was able to do at my shop. That said, the sniffer came out pretty close to the temp WB readings I was able to get)

 

I will also add that getting the voltage constants correct can be key in proper fueling of the car. Though you monitor and get MAF fueling correct -- at a given voltage -- there can be differences in how each injector reacts when voltage decreases. (Don't often see INCREASES if voltage regulator is working. Of course, decreases should be rare too...if the charging system is working as designed.)

I'm saying -- while it can be helpful...it's not critical. It probably helped me a lot because my alternator has been giving me (intermittent) fits for a couple of years. (Finally figured out the regulator is going south)

 

The injectors are from FIC(Jon) but I was provided with no info and he isn’t responding to emails.
guess he is busy moving?

 

Maybe...I saw the email announcement...about the move! Guess you could call. Or...use the part # to see if you can find specs page online.

 

What a minute! I am WRONG! My 24lb SVO are 2nd generation Bosch now that I think about it. Bosch 3's are what I put in my Jeep (back in 2012). I apologize for misleading you...and possibly making you think the values I posted might be correct. They won't be. I believe model 2's don't atomize as well as the OEM injectors -- which might explain the significant difference in PW you see in my values!!! They "inject" in more of a stream. That said, I'd be more likely to bet on the make-up of the coils as being the bigger contributor to PW vs voltage.

LUCKILY...You seem to take my advice in getting the correct PW tables for voltage!

 

Funny thing is yesterday I did try those values you gave me. Car took a few tries to start. I data logged going uptown and it showed lean on the long term. Wasn’t crazy lean but around 134-136 if I remember right. I can always go back to the bin I previously had so not a problem.
I will have to wait and see if I get email back for correct data on the 24 lbs. looks like by lowering the offset with voltage should help lower the injector constant.

 

You might also follow the "trail" through this thread at 3rd gen. It might lead you to the PW constants.
https://www.thirdgen.org/forums/diy-...or-sticky.html