This is a little long because I am being very thorough to save some of the back-and-forth. Am on my way to installing Huron Turbo kit in a Daily Driver 99 Trans Am (CAR IS STILL STOCK NOW THOUGH, no boost), I am going slow step by step (mostly so I can keep driving it). I need to figure this out so I can take this car to work, if I can't get this working within a few days I'll need to put the old injectors/tune back in it. Please help me so I don't have to take that backwards step.

Just basically trying to get Deka 80's to work in a stock L33 engine. This gotta be something simple!

Car is 99TA and has a stock L33 (with only upgraded valvesprings/pushrods) with stock cam and hotwired stock fuel pump and stock regulator/rail stock fuel pressure. That's it, nothing special. Fuel pressure looks good, and using an older Frost LS1 tune I bought a long time ago (for the original 5.7) the L33 has been running amazingly well for like a month on stock injectors, good AFR smooth idle and almost 20MPG. Haven't even tuned it, trims seem pretty good even for a 5.3 with a 5.7 tune. Been running the car for like a month and maybe a few thousand miles like this shaking out any glitches, have been none.

Next step towards my turbo was to install injectors, based on info here (and Denmah posts) I installed Deka 80's described as "8x Siemens Deka 80LB 850cc Fuel Injectors 110324 FI114992: Flow Tested & Cleaned" from "KM Racing" putting the fattest two on cylinders 7 and 8. KM Racing had lots of good feedback, seems like they focus on injectors, I don't think there's anything wrong with the injectors.

Using tune described below, the car started and ran good, seemed fine/normal. Started easily, Idle seemed smooth, but stumbled a bit when I goose it. Checking the scanner I see that it's running very rich at idle and when rev'd (like 10:1 AFR) and I do see the exhaust being rich. I believe the wideband is accurate because it was showing 14.6 on old injectors earlier same day, also the computer tries like heck to pull fuel out (super negative trims, see screenshot) so computer's O2's also show extremely rich as a validation it is indeed extremely rich. Also note that the trims nosediving don't seem to help the AFR very much at all.

I have done a lot of reading, and can't seem to get this figured out, here is exactly what I did, please tell me what I'm missing. Tune is attached.

Started with my LS1 tune that was working great with old stock injectors on stock L33, I followed the sticky and other notes from this forum:

My changes:
Fuel-Transient-Min Fuel Milligrams - Went from 0.045 to 0.019
Fuel-General Copied sticky "Flow Rate vs. KPA" entire table.
Fuel-General Copied sticky "Injector Offset vs. Battery Voltage" entire table.
Fuel-General Copied sticky "Short Pulse Adder" entire table.
Fuel-General Copied sticky "Minimum Injector Pulsewidth" entire table.
Fuel-General Copied sticky "Defgault Injector Pulsewidth" entire table.
("entire table" means the table in the Deka 80 Injector Sticky HPT file)

Here is a cold start, notice when (I think) it hits closed loop it tries like heck to pull fuel. The one blip where revs go up momentarily was me goosing the throttle.

Also tried with and without MAF, same result. This screenshot showing unplugged obviously.

 

I would like to add that I tried a lot of different values for the transient milligrams, ranging from lower numbers like .0002 and even some higher, and it made no difference in the rich idle.

Also note that I pulled 25% out of idle airflow and it didn't seem to help either so I don't think the problem can be tuned out that way.

I also tried "MIN INJECTOR PULSE" set from .593 to .175 (but it would show as .182?) per a thread stating this worked on a stock build, did not fix.

if someone has a tune of a stock LS using Deka 80's that isn't rich at idle I'd appreciate it if I could get a copy of your tune to check out. Can't seem to find the right recipe.

I understand that running the car like this risks washing cyl walls with gas and can hurt engine, so not driving until resolved.

EDIT: Someone pointed out one error, Short Pulse Limit was still the old value. I missed that because the text accompanying the injector data didn't list it in the checklist. I will be changing that to 2.508 and also Min Fuel mg will be put back to 0.016 as shown in the spreadsheet (mine 0.019) so that's back to matching the spreadsheet as well. Will retest maybe lunchtime today.

If I don't get this figured out, I'll need to take a large step backwards by putting stockers back in, I don't know how I'll recover from that setback since I need the injectors in the car to test, but I need to be able to drive the car. Any help would be appreciated, especially a sample Gen 3 tune for stock engine and Deka 80's that idle at correct AFR.

Edit #2 (update): No change after changing short pulse value. Car is 10.x AFR at idle and at all RPM ranges, even when I let it sit at 2000 rpms and let the trims try to pull out fuel, I see the trims nosedive to -40's but AFR remains in the 10's. With all the hundreds of people who have done Deka 80's in uncammed soon-to-be turbos, there has to be someone who can shed some light on this for me, right?

Thanks all.

 

Tried knocking down the Minimum Injector Pulse Width as described in this video. Same results. Car is locked at like 10.2 AFR in both OL and CL, even when trims try to pull it down the AFR doesn't respond. This is not just at idle, if I press the throttle and get it up to 1500 RPM and hold it in one cell and let the trims adjust, the trims nosedive to -40's and the AFR stays at low 10's.

 

Bump: New Question: I have a working recipe that does NOT resemble the Deka 80 Spreadsheet AT ALL but car is idling and driving pretty well at apparently stable correct and trimmable (and likely tunable) AFRs. This was just a jumble of trial and error on injector settings and tables. Didn't involve any VE adjustment or other non-injector setting changes.

Is there some reason I should not use a hacked up injector recipe, as long as AFRs are stable and correct? EDIT: I mean after tuning it, sorry I wasn't clear.

It seems that an injector is a binary thing, it's either ON or OFF and only for a specific duration. Is it true that *any* recipe of injector data that keeps the trims in line is the same as any other? Or is there some concern that even though my hacked recipe has AFR and trims working, some underlying incorrect injector setting could still harm the motor in some way? Seems like an injector comes ON, stays there for a duration the PCM needs to satisfy AFR, then goes off and any recipe that does that is fine.

If I can't find a "correct" recipe I may just tune this hacked recipe, going very slowly and carefully along the way of course. Opinions welcomed if there is any reason not to do this. At least I have the car on the road again.

 

Even with the new injector data, you'll want to touch up on the VE and MAF calibrations. If not, it'll naturally run fat.

 

You're right. The trims are showing it's fat, and not close enough to zero for my liking with this injector hack. I edited my prior post, I wasn't clear. I do plan on doing a full tune. Probably will skip the MAF and just stay in SD mode since a turbo is on the horizon. I am just trying to think if there's "any" injector setting that might break something down the road that I'm not realizing, or is the proof in the pudding and correct AFR is all that counts.

Have not yet gone into PE mode to see what that looks like.

Anyone else have any input? Would you'all just "tune it and send it"?

 

The 80lbs Dekas are a popular option and there is data floating around the web that seems to work okay. I'm currently running them in my Camaro and adjusted the min pulse to my liking.

As long as you have all of the main data points populated you should be good to go. Below is an example of what can be found online.

https://www.aacorvette.com/injectordatahp.html

 

I really appreciate your input. I never ran across that injector data link while searching, will bookmark it.

Apparently on other message boards this topic seems to be taboo or something, "real" tuners don't want to give out this information because they had to BUY either a data disc or DVD to get it for themselves, so they want everyone else to pay for it, or pay a "real" tuner. The silence here was making me think that might be the case here too.

I "thought" I had all the right data from the Deka 80 spreadsheet and sample HPT files, but the car would never respond to tuning and would stay at like 10.x AFR both at idle and at low-mid RPM so "something" was wrong. And, it had to be something in the injector fields because my hacked stuff worked and those were the only fields I tinkered with.

But, I really needed to get the car on the road, so I spent a few hours last night tuning and I have these Deka 80's running beautifully (less than 5% afr error through whole table). So anyone reading this, I am about a "worst case scenario" for running Deka 80's in the LS world as I have an unboosted stock L33 (5.3 litre) with its stock cam and am among some of the lowest airflow an LS will see (I know the L33 cams aren't the smallest and there are smaller displacement LSs but still)... and I, the average Joe tuner, have been able to get the Deka 80's running very smoothly and at a reasonable and controllable AFR at (for now) 750rpm idle. So don't believe all those threads out there that say Deka 80's aren't tunable for low airflow. I still need to do the Russ K idle config some morning which will likely clean it up even more.

I have not gone into PE yet with it, just needed to get it driveable. Gotta say, tuning with a Yank 4000 is TOUGH because it hits the same few cells in every gear on every slope LOL. (I don't have the TC locking right now, another topic).

So verdict is, I'm running with it.

If I hit any glitch when I start boosting I'll update this thread for future searchers since I really believe in the idea of sharing and want to keep that attitude alive here.

 

Excellent man, I bought the dvd and books years ago lol as well as paid local and remote tuners. After learning on my own builds, I've come up with a formula that works well.

Now I provide tuning locally and enjoy helping others whenever I can. All of the information can be had for free online, but I can respect those who put forth the effort to compile the information into one package.

 

I'm not going to say I am a professional tuner by any stretch, but if your within 5%, it starts good cold, and warm, idles good, tips in crisp, I'd say your doing something right.
Now, it's possible it could make a little more power with different settings, but that's a whole different topic.
Good job on getting in there, and just learning!

 

Thank you for the reply. Yes, idles well, all AFRs are good but one glitch I can't explain. Seems to be about 2MPG lower right now with JUST injector swap. Now the weather is getting colder and I do find myself idling more (for heat) but I don't remember that happening last winter for example. That has me a bit worried. I watch continually with Torque App throughout the day and I see O2's switching normally at cruising/idling etc so I think everything's OK.

Using bastardized injector settings just has me paranoid maybe LOL.

I guess the proof will be in the pudding... am installing a turbo as soon as first dusting of snow hits (Pittsburgh area, usually hits before halloween). We'll see if the injectors hold up well when I load 'em up using single digit PSI LOL.

 

I think the mpg loss is fairly common. You have a much larger injector in it, and you can only control so much with that size/quality of injector. I also have Deka 80's, so I am not knocking the injectors, it's just part of the nature of it. On a stock ecm, it's not quite as simple swapping injectors as say a Holley. Granted, the tune should always be looked at, it's just a little easier on a Holley IMO.

 

Ok, makes sense. I'm just going to run with it for now and will watch fuel trims and keep the O2 oscillations up on my head unit's Torque App as I drive it for work.

Actually, there was one more change I made, I never did the MAF tuning after the injector swap and left it running in SD mode, did not tune the MAF because it won't be used in the upcoming Turbo step. Maybe this reduced accuracy of air measurement is contributing to the MPG loss. Didn't think of that until just now.

If trims all stay single digit and I see those O2's oscillating all the time I'm going to assume the daily driving (non-PE) tune is solid, and the MPG loss is just a side effect of large injectors being less "accurate" and controllable.

I'm gonna watch it like a hawk as I add boost here soon and finish up the PE tunes that go along with that. I'll probably get an in-car AFR gauge or find some way to monitor that day to day, not sure if I can get my Android head unit to monitor that.

I do have the PE mode very fat right now (like 10AFR) just to be on the safe side in case I need to run it hard (for merging or something) but am staying completely out of PE otherwise so I don't think that's killing the MPG. No use spending a ton of time tuning the PE with these injectors since I'm doing the turbo here soon (like in a week or two).