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Injector offsets for 24lb South Bay TPI injectors?
Hey - I've searched quite a bit and can't find a good reference for the battery vs. voltage offsets on the 24lb Bosch DIII's.
The injector number is:
0 280 155 703
Also - I see talk of a "Low pulse width offset" table or something along those lines. I'm running $6E and I don't see a table like this. Only the offset vs battery voltage table. I'm using the definition file that came with TunerPro RT. Could it be that this table isn't defined in this file?
Re: Injector offsets for 24lb South Bay TPI injectors?
Did you not get a calibration summary with the injectors?
Also - I see talk of a "Low pulse width offset" table or something along those lines. I'm running $6E and I don't see a table like this. Only the offset vs battery voltage table. I'm using the definition file that came with TunerPro RT. Could it be that this table isn't defined in this file?
OK, so I'm about as new as you can get to all this, but I'm gonna give this a shot. "low pulse width" being defined as non linear flow, right? Way down low on the short end of the curve? ....did injector companies even HAVE that data back when GM was programming these cars? That's a relatively new technology if I understand correctly. My Holley EFI did not have a table for this, and it's pretty new. ...and it's gotta be a pretty big injector to get practical quality difference from a properly tuned "LPW" to an inproperly tune LPW I would think. ....again....I'm a EFI/injector tuning newb.
EDIT*** just to add.....my thought would be that you may be correct in that there isn't a table defined. Again...not an expert, but trying to think through the MASSIVE amount of info I've attempted to absorb lately on the subject.
Re: Injector offsets for 24lb South Bay TPI injectors?
I don't remember seeing a calibration summary. But it's been a while (like a year) since I installed these. Bought a chip at the time. Now I'm trying to do some corrections and tuning on my own..... I'll look for the box and documents.
So here is the thread where I see it mentioned that with the Bosch DIII's I should zero out the Low pulse width offset table due to them flowing more fuel at small pulse width. Which I'm finding to be the case - my idle BLM's are a good 10 points higher than everything else in my RPM vs LV8 vs BLM table.
Re: Injector offsets for 24lb South Bay TPI injectors?
I think this should work. The "A" version I have in my screen shot is something I was tweaking and I don't remember what I changed lol. But this is the original XDF I found.
Re: Injector offsets for 24lb South Bay TPI injectors?
No problem. It is a pain. Took me forever to find some for my injectors. And even then it was a close calculation I found of some ones online and has required tweaking since to get it closer. Good luck. I'd give you my offsets but I am running a different Bosh III lol.
Re: Injector offsets for 24lb South Bay TPI injectors?
I believe if the injectors are modified factory injectors to get to 24lb, the tables will need to come from the company that modified them, through direct measurement. Tables found online that are based on the part number on the body of the injector may no longer be valid. It becomes a crap shoot at that point, about how far off they are. Not saying it can't be tuned, but it could end up a huge PITA to get right.
That's a large reason why I went with box stock factory injectors, since the tables corresponding to Ford p/n I know are correct.
Re: Injector offsets for 24lb South Bay TPI injectors?
I've been playing with the injector offset vs. battery voltage and I zeroed out the low pulse width table. I also dropped the minimum and default pulse width to 1.05 msec.
Playing with the offset vs. battery voltage seems to be evening things out. But I'm finding that the "24lb" injectors seem to be wanting a 22.5 lb injector constant, which us consistent with the data I can find online:
Which is 238cc (22.7 lb/hr) @ 44.1 psi. Which is about 22.5 lb/hr @ 43.5 psi.
It would still be nice to know the actual values for the offsets.
The closer I get to "correct" offset values (as close to 128 across the board), the lower the flow rate of the injector becomes. So are these sold as 24 lb/hr injectors only when used as a drop-in replacement with zero tuning? Because it seems once tuned with all their accurate offset data, they turn into 22.5's.
Re: Injector offsets for 24lb South Bay TPI injectors?
Yeah, you may end up with a flow rate value that's different than advertised.
btw....I hope you're using a wide band O2 to tune.
I kind of iterated between the BLMs and the PE to get the most consistent response with a particular flow rate. Ended up settling on 31 lb for 30 lb injectors. But you need a wide band to see PE response.
In the end though, if the car is running the way you want, it really doesn't matter what offset values you're using.
My experience (you can look it by searching on Bosch III and then viewing my threads) is that if it's too far off it'll be extraordinarily difficult to tune. If the correct or close to correct, it'll be a lot easier. On the thread where I tuned a friend's car after an injectors swap it was as easy as putting in the offsets and changing the injector constant... everything fell into place after that.
Basically what's happening is that as your car warms up, the system voltage changes over time. The ECM needs to know how the injector pulse widths vary with that voltage since it'll just assume the injectors are delivering the amount of fuel it's telling them to. This is even more critical in PE since it doesn't even look at the O2 sensor in that mode.
Re: Injector offsets for 24lb South Bay TPI injectors?
Yes I'm using a wideband. PLX Bosch 4.9. New sensor.
So I've done a bit more refining. I did end up putting the injector constant back up to 24 after more logging and playing with the injector offsets. Here's where I'm at now:
Minimum base pulse width: 1.05
Default base pulse width: 1.05
Here's what it looks like after a mixed drive around town and freeway:
How am I doing?
I just started doing this last Monday or so - in the evenings after work. So if I'm screwing this all up please let me know. I'm not expert on this - I've only tuned on newer Imports in the past.
Re: Injector offsets for 24lb South Bay TPI injectors?
I tweaked the MAF 5 and 6 scalars a bit and I'm around the 12's at WOT. I'm doing this on the street though so not really able to get into table 6 I don't think. I'm not currently datalogging wideband. Just watching it. The cruise and closed loop idle hover right around 14.7.
Re: Injector offsets for 24lb South Bay TPI injectors?
I don't see any drastic numbers when I'm hammering on it. It's hard to see the transients when going from cruise to WOT, etc. I'm running the wideband off a tailpipe clamp and not datalogging it. But I don't see any knock and don't feel any bogging or lean surge or anything so it must be close.
It's basically just a stock 86 305. I'm using the 89 BIN though so cam is different and such. Only mods are to the intake - redone with a cone filter and such to accommodate the serpentine system but being a firebird I didn't have the 88/89 intake and the stock on interfered with the A.C..
Re: Injector offsets for 24lb South Bay TPI injectors?
So I am getting some slight knock when I hammer it. What changes would I want to make to PE, or AE to pull up my AFR's during this tip-in to keep it out of detonation? My WOT narrow band is a little over 900 which I understand is a good place to be. Wideband shows about 12.5 AFR at WOT. Here's my graph with a couple reference points of before and after tip in. O2 in red, RPM in blue, and Knock count in green:
Re: Injector offsets for 24lb South Bay TPI injectors?
That's one thing I have a lot of experience with. The wideband is no problem being in the tailpipe. That's how we do it on the dyno all the time. Amazingly it barely affects the readings if at all. I have a friend that's a famous tuner (in the STI, EVO, GTR, etc world) and he does road tunes all the time with this same setup. I've talked with him about it and he says *maybe* would cause a change of 0.1 AFR... If even that.
Also I've watched the narrow band and it's cross count, etc. The wideband agrees with the narrow band cross counts and voltages when in cruise. At steady state cruise, O2 sensor cycling normally, the BLM at 128, I'm show 14.6 - 14.7 on the wideband. So I'm comfortable that it's accurate. Possibly a bit delayed in it's reaction but not much. Less than a second it seems like.
Any direction on knock mitigation? Thinking I need some AE?
Rick
Last edited by GeneralDisorder; 05-13-2017 at 09:15 PM.
Re: Injector offsets for 24lb South Bay TPI injectors?
Hey Vader, you wrote this in another thread:
The EST system will disable the Burst Knock logic and bypass the RPM and coolant temperature criteria for ESC retard enable. That will force the engine into a condition where spark knock should occur if the throttle is suddenly opened (Burst Knock).
Am I experiencing "Burst Knock" on rapid throttle opening and will flipping the switch to remove the 10k resistor once the datalogger is connected stop this from showing up in my log?
Thanks!
Rick
Last edited by GeneralDisorder; 05-13-2017 at 10:45 PM.
Re: Injector offsets for 24lb South Bay TPI injectors?
From what I've researched and read, you should always remove the 10k after the log is started get it back into normal mode. Or flip the switch on your APU etc. I am honestly like you and still learning as I go as well lol.
Re: Injector offsets for 24lb South Bay TPI injectors?
Ok excellent - tomorrow after I take care of my mother's day obligations I'm going to check out this 10k switch that I'm supposed to switch after logging is started despite not being mentioned in any of the documentation or most other tutorials I've read. Good thing the search function works around here.
05-12-2017, 08:16 PM
It is a pain. Took me forever to find some for my injectors. And even then it was a close calculation I found of some ones online and has required tweaking since to get it closer. Good luck. I'd give you my offsets but I am running a different Bosh III lol. 
