95 lt1 injector offset questions

[sherlock9c1]

Any fool can go in and set the flow rate and the motor will run fine above 20% throttle. But if you want idle and part-throttle drivability, and especially if you want it to start quickly and smoothly, you have to have the short pulse adders and voltage offsets correct, respectively.

The way Ford labels and characterizes their injectors is really helpful - they actually have a number called MINPW which is the minimum pulsewidth the injectors will reliably fire. The last time I sized injectors for a friend's build, we were looking hard at injectors that had this data available. For this particular situation we actually discovered that a set of 80lb injectors had a lower MINPW than the 60lb injectors he was considering, even though the 60s would have met the fuel needs of the motor. Given that this was a heavy manual transmission car, I insisted that the injectors be able to reliably fuel down to 400rpm during clutch engagement, and so the 80s would have been the better choice despite their higher peak flow.

Ford also includes two slope values (a high slope and a low slope) and a transition point. This transition point is where the pulsewidth gets so short that the magnetic field delays and the pintle rise/fall times become significant relative to the requested pulsewidth. Here's an example. https://performanceparts.ford.com/pa...-9593-lu34.pdf It's at this transition point where the GM short pulse adders start to grow. There are some posts out there how to convert the elegant Ford values to the verbose GM values, but the result is perfectly characterized injectors from the first crank.
Personally I'm running 2011-2017 Ford Mustang GT injectors in my LT1 with fabulous drivability.

It continues to blow my mind how places like Racetronix advertise GM injectors with NONE of these critical parameters available. Maybe they have it on their forums, but their rules state you have to buy something before they'll give you forum access. Huh?

[hotrodf1]

I'll add too - when I swapped to Bosch D III injectors , just 32 lbs, I found that I had to just zero out the pulsewidth adder (not batt. voltage offset), because the Bosch injectors are the other way. I was told they flow more fuel at low PW, and with LT1 you can't take away only add, which is the wrong way. So it depends on which injectors you use as to what all you change in the tune. FIC was absolutely no help on this, even though I bought the injectors through them. They had the data somewhat tailored for the LS1 crowd.

[Mr.owl]

I'm running fic blue demon 36lb injectors had same issue fic was no help. Issue I'd been having was cruise drivability bucking and the afr bouncing a lot. granted I have a pretty big cam. But idle and fire up have been no issue. I'm running sd because I was having issues with maf tuning with my 110 LSA but I've got it pretty close now in sd without changing my adder thanks to trimalyzer. Still think there's more room for improvement there though. But what you're saying is you zeroed yours out? Think I should go back to my base tune zero them out and start over?

[sherlock9c1]

I'm running fic blue demon 36lb injectors had same issue fic was no help. Issue I'd been having was cruise drivability bucking and the afr bouncing a lot. granted I have a pretty big cam. But idle and fire up have been no issue. I'm running sd because I was having issues with maf tuning with my 110 LSA but I've got it pretty close now in sd without changing my adder thanks to trimalyzer. Still think there's more room for improvement there though. But what you're saying is you zeroed yours out? Think I should go back to my base tune zero them out and start over?

Why not give it a shot, and if it doesn't work, go back to what you had.
I don't have experience with this issue, but what came to mind was this thread on here where they delayed the injector start time until after the exhaust valve closed to avoid putting raw fuel into the exhaust. Have you tried that to see if it cleaned up the AFR instability when running in MAF mode?

[spfautsch]

I ran across this thread a week or so back when I "forked" an EOIT thread to hopefully spark more focused and meaningful discussion on that particular subject.

Anyway, the more I read the more I find in common. I'm also running a set of "recapped" / redrilled inectors from FIC. I asked them for data ahead of the purchase and was promised something would be shipped with the injectors but found no such information included in the shipment and received no further responses from them on the subject. These were sold as 42lb/hr bosch IIIs. Upon opening the package I found a set of 8 GM 12561462 / Bosch 0280155931 grey injectors that likely began life as 28 lb/hr LS1 injectors.

Back to the present - several hours of reading later (most important reading found here) I come to a fuller realization that the original injector data is likely all but useless.

So I'm wondering if anyone has any ideas / recommendations on who might be able to properly flow test injectors. Not an injector cleaning shop type test, but a real characterization test that demonstrates slope and offset at different pressures and voltages.

Any fool can go in and set the flow rate and the motor will run fine above 20% throttle. But if you want idle and part-throttle drivability, and especially if you want it to start quickly and smoothly, you have to have the short pulse adders and voltage offsets correct, respectively.

I'm discovering that the slow and painful way. Though I've achieved relatively decent results using the SVO injector offset vs. voltage table, I think more accurate injector data couldn't hurt. After "a lot" of reading on the subject I've come to find that anyone that tests injectors and specs static flow rate should probably not be trusted to provide a truly matched set of injectors. And by matched I mean injectors that share the same flow characteristics at all pulsewidths, pressures and voltages. I believe this is why this particular company generally removes the Bosch part number from the body, and sometimes paints their "matched" injector sets (blue, hence the name "blue demon").

Personally I'm running 2011-2017 Ford Mustang GT injectors in my LT1 with fabulous drivability.

Would you have a part # on those?

[sherlock9c1]

BR3E-EB-B556V is what I just pulled off the bodies of a set on eBay. I'm not near the car at the moment. Just make sure not to get the 18-19 ones as they're much smaller flow since Ford went to a combo direct AND port injection setup in 2018.

[spfautsch]

BR3E-EB-B556V

Thanks! Those look to be a drop-in except for the connectors. The only thing I dislike about using the Bosch injectors in place of the fat body Multecs on the LT intake is the need for something to stop them from "falling out" of the fuel rail. On my current injectors I cut stainless lock washers and fit them into the groove above the lower o-ring, but these look like the shoulders are large enough to act as stops.

Edit: nevermind, I just found your other post on these here (datasheet also). I guess that'll give me an excuse to turn some spacers for them on the lathe.

[sherlock9c1]

Yeah, as long as you don't start a run on these injectors on eBay. I need one more set for a car I recently acquired and am grousing about having to pay $90 shipped for a set when Rousch was selling new takeoffs with 3 miles on them a few years back for $49 shipped.

Wow those injector pulsewidths are wacky! Almost looks like one of the data streams is getting smoothed or something. The cold start one is really wacky. If you have dual exhaust, do the tailpipes smell different?

[spfautsch]

On the warmup log, I've mentioned before about the RHS injector dropping out at about 56-60C

Are your individual cylinder trims all set to 1 or have you tweaked them?

On the drive log, the two Injector PW are all over trhe place. NOT seen that before.

All I'm saying is you seem to be continuously chasing ghosts and the modded injectors seem like they might be the common thread.

Yeah, as long as you don't start a run on these injectors on eBay. I need one more set for a car I recently acquired and am grousing about having to pay $90 shipped...

Sounds like the run is already on. $90 for 8 sounded like a good deal to me so I grabbed a set this morning that had that part # specified in the main / short description. But in the seller description after the seller specified they came off a 2016, the part # they give seems to be the 2018-19 small injector (JR3E-9F593-AB). So I'm already off on the wrong foot.

[Terminal_Crazy]

Are your individual cylinder trims all set to 1 or have you tweaked them?

No. I've measured the difference in AFR by dropping each cylinder & scaling off one of the centre results.

All I'm saying is you seem to be continuously chasing ghosts and the modded injectors seem like they might be the common thread.

I'm out of ideas.
These are from Fuel Injector Clinic -http://fuelinjectorclinic.com/ls1-ls6/IS301-0445H
... These injectors utilize the latest technology and provide great linearity and short pulse width repeatability.

After several sets, I'm fairly comfident it's not the injectors.

The run is already on. $90 for 8 sounded like a good deal to me so I grabbed a set this morning that had that part # specified in the main / short description. But in the seller description after the seller specified they came off a 2016, the part # they give seems to be the 2018-19 small injector (JR3E-9F593-AB). So I'm already off on the wrong foot.

Don't you just love this hobby :-)

Mtch

[Terminal_Crazy]

Just done a warmup with a base log.

http://www.sand-hill.uk/Terminal_Cra...une-Warmup.jpg
http://www.sand-hill.uk/Terminal_Cra...-Warmup.eedata

I altered the bare minimum
12B4C * Injector Flow Rate changed from 24.912 lbs/HR
129D5 * Injector Voltage Offsets changed.
129F5 Injector Offset Adder changed.
129F5 Injector Offset Adder changed.
126d5 Min Injector Pulse changed from 1.40 BPW (0x005C)
126d7 use this value when MIN inj pulse reached changed
12B4E Cylinder Volume changed from 717.25 ml/Cyl
12BEE * VE Table - Primary (400-2000RPM) changed.
12C8A * VE Table - Extended (2000-7000RPM) changed.

Forgot to switch off the MAF
EGR,EAS (AIR pump) AND 1-4 control DTC's Not switched off.

Sounded much louder & rougher idle but only 800rpm
It went CL when Splits 121-133 appeared so of course PW don't match.

Questions
Why do Inj PW start off different in those earlier logs?
I thought OL didn't use the O2's
BLM's under 128 are not remembered

The 2 scalars
126d5 Min Injector Pulse changed from 1.40 BPW (0x005C)
126d7 use this value when MIN inj pulse reached changed

I had them sat at 0.79 which is where these injectors should operate (min Inj switching)
Is this too low ???
This is idling around 2ms. I was around 1.65.
Lowest PW went down to about 1.0...

IF I set it around 1.00 it shouldn't go lower than that and go any leaner than what 1.00 would inject.
ie IF PCM requests 0.8 mS we still get 1.00 worth of fuel ?
Inj Offset Adder table tually starts adding fuel at 1.220 mS now

PCM hardly ever went below 1.00mS as AFAIR even with the Black Ops in.

Mitch

[sherlock9c1]

I'm sure that's the right part number. I've been watching several of those auctions and the 2018-2019 ones have a white clip around the upper ends of them. Immediately contact the seller if there's any confusion. eBay gives buyers an hour to back out for any reason and you can also cancel if the item is not as advertised.

[kur4o]

The only thing I dislike about using the Bosch injectors in place of the fat body Multecs on the LT intake is the need for something to stop them from "falling out" of the fuel rail.

I run in the same issue with 98 ls1 injectors, the remedy was to add a second o-ring in the upper slot. Worked really well.



I resolved the injector problems long time ago. Just grab yourself a good GM ls injectors and read this thread
http://www.gearhead-efi.com/Fuel-Inj...njector-tables

I even have an updated version that reads injector voltage for ultra precision.

When I switched over from a crap Accel to stock 98 ls1 all of the surging has gone. So definitely crap injectors do cause surging.

Another thing that I noticed shortly before the crap Accel died completely. When cold they run fine only to turn to crap when warmed up. The AFR was jumping all around with no reason and the engine was untunable.

[spfautsch]

I run in the same issue with 98 ls1 injectors, the remedy was to add a second o-ring in the upper slot. Worked really well.

This is what I did with my Bosch D3s and it worked well also. I found out from experience the o-rings can slip if you get in a hurry to slap the fuel rails back in and the pressure side isn't seated fully. These are pretty sturdy and there's less chance of fuel spraying everywhere.

0912181955.jpg

I've seen your LS table mods and that's very cool. My concern in this thread is geared more towards modded injectors and inaccurate characterization data.

[yoheer]

I installed new injectors. I have its specs so I know flow rate and offsets.
What about Injector offset adder table?
Should I zero it out or just leave it alone?