EagleMark

Well you know the old saying? "Give it what it wants!" Yeah OK, but tuning injectors without proper data is just ridiculas and trying to give it what it wants, and works? Well I'd be embarressed if someone looked at the tune!

But it did start cold good, ran good, drove good, WOT good, hot start good.... that's bottom line... but nothing was tuned right in bin!

I guess some guys can put up with all the issues as long as it runs good when warmed up? I can't!

I just stopped tuning any injector change that had no data! Can be done but life is to short... Now I tell guys and then

Dominic Sorresso

For the most part, my car ran fine but like you, I'm a bit "embarrassed" by my VE table. Fortunately not many ZR-1 owners would know what to look at. Sort of reminds me of when I spent an entire year tuning my Xfire. It had an erratic idle and the motor would mysteriously shut down at a gas station or something.
I am sure there are threads here about it. Well, one day I started tracking down an oil leak from the back of the manifold when I discovered that I had used FelPro 1010 head gaskets. The fire ring on #7 was bent in towards the cylinder and so I was pumping exhaust into the coolant. The plug was steam cleaned.
Other cylinders were starting to show the same thing happening. I actually had hydro locked the motor at one point and didn't realize it. Well the good of it came into forcing me to learn about PID controls and tuning for a larger cam.
I'm thinking this is another "learning event" for me.
Sometimes tuning feels a little like being Sysiphus.

Dominic Sorresso

So EMark,

Finally was able to drive car yesterday. The BLMs were pretty much pegged at 115 using the new IB values. For my next step, thinking of globally dropping VE
by about 10-15%. Again, I noticed that after some AE, I got a stuttering from the motor and the WB showed it going very lean until it cleared out. Not sure if that is a function of the injectors, which u have observed as well, or that AE has been enriched to the point that the ECM is attempting to "clear things out".
DFCO is disabled and LT-5 does not appear to have any enleanment params.
My question is whether I just make reductions to just VE or apply similar changes to AE as well? Or just rely on the VE changes, then dial in the auxiliary controls once VE is dialed in?

Dominic Sorresso

Decided, with the help of a tuning Yoda, to address this using the VE tables at first. I dropped VE by ~12% in the lower kPa/rpm area of the table. Didn't have chance to datalog, but warmup/idle was pretty good. More later.

Dominic Sorresso

Ran an initial datalog and BLMs still "Pegged". Taking another 10% out. Meantime, 12% was a bit much for the idle so putting back about 5% in that table.

Dominic Sorresso

Been able to do a few runs. The last one I datalogged after doing a "global"reduction of fuel. The lower rpm/kPa region is still rich but cruise and idle areas are coming in nicely. One observation is that the BLMs on both banks are much closer together. There still is a "split" but the variation on left to right banks is now within 7-10 counts instead of 20, ie 133-125. Still getting a few areas where the injectors just seem to shut off and where the ECM falls out of closed loop. I suspect that the O2 voltage is moving somewhere below and above the O2 C/L window settings. Usually w a blip of the throttle it jumps back into C/L and Learn. I am thinking I'll leave this alone and see if it doesn't work itself out as I get closer to good tune.
What's also interesting is how much steadier the BLMs are and how much more quickly you get to a pretty decent tune level.

Dominic Sorresso

EM,

The car is running better w each successive tune. My last datalog definitely showed removing more fuel at the low RPM/low MAP region of the VE. I continue to run into the same injector behavior you described a bit ago. There are times that the motor stumbles and looking at my WB display, I can see the AFR nearly shutting down. I have reviewed the datalog and don't see a specific cause of this happening. The BLMs are running at about 115 during the point this seems to be happening. But trying to accel, the motor will stumble and then recover. One other thing I am seeing, not related necessarily, is that during cruise, I'll see that the ECM is going O/L. Here I am suspecting that due to the change in the IB, the O2 sensor V is above or below the C/L window.
You have done some modification of your DE settings, but I don't find any such params in the LT-5 cal.

Dominic Sorresso

Pretty interesting results coming from changes to the IB. The "split BLM" issue
has really changed. The left bank was almost always leaner than the right. And by quite a bit. That differential has been reduced significantly to the point that the BLMs track much closer even being on the same side of 128. Sometimes the left is richer than the right. I continue to see some areas where the injectors appear to turn off although I have DFCO disabled. It appears to happen at about a TPS voltage of about ~ .7v. Need to check and see if it's switching from secondary throttle on/off. As an explanation, the LT-5 has 16 injectors. These turn on/off depending on throttle position. I have TPS% for idle set at 1.95% so that could cause secondaries to shut off. Need to investigate that.

EagleMark

Dominic, Sorry I missed these posts, I've been pre-occupied for almost a year now being sick and just got out of hospital from cancer surgery...

Some of this stuff I forgot, some is coming back to me. I'll have my hands on this vehicle again here this summer and plan on a start from scratch re-tune to see how numbers come up when proper injector data is used as a starter point.

My feelings so far are... even with correct Accell injector data, there are still some quirks to these injectors.

From reading your posts you seem to have similar issues... but my cures did not work? Have you watched BPW times when this is happening? Wondering if your hitting a minimum BPW which is turning off injector?

Dominic Sorresso

So sorry to hear. I went through that with my wife last year. I wouldn't wish it on anyone. I hope things are getting better for you. We are very fortunate to have excellent facilities here in Chicago. Can't say enough about the Cardinal Bernadin Cancer Center at Loyola. Amazing how strides have been made in treatment even over just the last 10 years since my father was diagnosed with colon cancer. At this point we can say my wife has been cured.

Going back to the injectors, it does appear to be happening at ~6% TPS. In addition, I am seeing the ECM going in and out of C/L, again at very low throttle but other than that I can't tell why. I see no other parameter change that correlates with it dropping out of C/L.

I've attached a zip of a text file from my last datalog. I will say it has gotten less frequent with each subsequent tune.

Dominic Sorresso

Did a log of the latest cal. BLMs really coming into shape. They track together in a way I have not seen before. Really close w each bank actually alternating as far as which side may be running richer or leaner than the other. This never happened before. Areas below 2000rpm are still "rough" in that the curves are not smooth or linear. Above 2000rpm, it gets a lot more consistent and I wonder if that isn't a function of the larger cams.
An additional observation is that the BLMs are also much more consistent. Once settled, they stay there. Previously, the BLMs were not as "locked in" as they appear to be now.

Dominic Sorresso

Still kicking this one around. I did implement the IB values off the Accel website, however, I realized that I am using the ones for the 24# injectors 150124.
The Accel injectors that sub for the stock LT-5 injectors is 150121, 21# injectors. I would at least like to confirm the values or get more accurate values. Have a call into Accel, but apparently they don't have values for this particular injector readily available. Looks like the 24# and 26# injectors have the same spec.
Anyone ever finally get hold of them?

Dominic Sorresso

I'm using the IB values from the Accel 24# injectors hoping they're close to the 21#. Looking at their chart, they show identical values for the 24 and 26# so I'm hoping they kept it all in the family. Calling Accel, they don't seem to have the 21# values available for some unexplained reason. I am hoping to get w someone locally who can flow injectors and has an oscilliscope. That way looking to get some real world values and see how close they are.
So far, the change in IB has made a marked difference in how the car runs. I got nearly 2+mpg higher at cruising speeds of 73-78mph.
EagleMark made a comment about Accel injectors seeming to shut down at times and I experienced the same thing as if ECM was going into DFCO. Even tho DFCO had been disabled. So I tried something else surmising that this was a problem w very small PW. I bumped the IB v Low PW table by 10%. The injector cutout went away almost completely. Idle was way smoother. Also, my exhaust does not include a resonator. Just headers, Xpipe and 3" inlet DynoMax muffs w Z06 exhaust valve actuators. It can drone at 1200-1600rpm. I have a vacuum solenoid/check valve on a ground interrupt to open and close the valves. With the change to the IB, the motor sounded soo much smoother and less raspy today. Nearly no drone even at lower rpm. One reason why I prefer a slightly leaner mixture. It sweetens the exhaust note to my ear. anyway.

Ronny

iTrader: (1)

I received the offsets from FIC. I see that Bosch rates the FP at 39.15 lbs? GM I believe is 43.5 so I believe I use 39.15 to achieve the fuel delivery of 24 lbs.

A few terms I am not familiar with:
low and high injector slope
fuel mass to switch low verses high
multiplier as a result of lower fuel pressure high and low
voltage offset I understand
voltage offset offset vs fuel pressure

It appears GM or Bosch has this fine tuned. Does GM and/or EBL accept this code? I presume if so I should make the changes...

RBob

iTrader: (1)

That data is from Ford, not Bosch. There is a thread here where I go through what needs to be done to use that data. Not sure where it is.

Hint: the low and high slope values is the fuel flow in pounds per second. Multiply it by 3600 for lbs/hr.

RBob.

Dominic Sorresso

A few observations regarding the most recent tunes that have developed w the update to the IB.

1. The "split BLM" issue has definitely been mitigated where now the driver's side bank can go richer than the passenger side. Never did that before.
The variance in the 2 banks is much smaller and sometimes non existent.

2. The BLMs track each other altho one may be a bit leaner than the other. However, they move in the same direction. Not true before.

3. The motor runs much smoother. Idles smoother.

4. Better gas mileage that appears to be supported by the motor now operates in a lower kPa range than before. I now see steady cruising in the 35-45kPa not 50+.

5. With the tweaking of the IAT table, I appear to be getting a much more consistent BLM across all rpms and kPa ranges. The variation is much decreased.

6. Exhaust note is much more mellow and the dreaded "drone" seems soo much less evident even at the lower rpms like 13-1400. Beyond that the exhaust note is a purrrrrrr.


I went for a logging session this afternoon and was just floored by how much smoother the motor was, how much more consistent the BLMs were even as CTS and Intake temp varied. WOW! Had not experienced that before.
Still don't think the IB is correct but it sure seems to be much closer than stock.
I have some areas in the VE Table that look a bit like black holes in the space-time continuum but it just seems to run soooo much better.

84Elky

Throwing this out because have also been dealing with the effect of this lately. Here's what I've discovered happens to BPW with the injector offset tables in the $8D AUJP code. BPW is initially calculated and then adjusted using all manner of conditions. But just before BPW is finalized:

• The Table at 0x040B=Injector Pulse Width Low Offset Vs. Base Pulse Width is used to possibly add a small uSec PW adjustment, but only if the current BPW is < 3.90ms. If >= 3.90ms, the table is not used. Further, in the original GM provided calibration, even if the final BPW is < 3.90ms, no adjustment is provided by the table unless the PW is <= 2.20ms because all the table values > 2.20ms = 0.00 (= nothing added). Because of this, it appears this table is primarily for idle adjustments and primarily to boost idle BPW when it is significantly less than 2.20ms. But the adjustment is small at normal idle. Assuming a BPW of 2.20ms at idle, 15.26uSec (0.01526ms) would be added, providing a very small 0.69% BPW change.
• But immediately after the above adjustment is considered or made, there is ALWAYS a PW adjustment for voltage if BPW is > 0 (eg - not in DFCO). The uSec value from the Table at 0x03FA=Injector Pulse Width Correction Vs. Battery Voltage (should just be "Voltage" -- see below) is added TWICE to BPW. If Switch 16, bit 6=1, keyed ignition voltage (not direct battery voltage -- again see below) is used to obtain the table value. If bit 6=0, fuel pump voltage is used. The adjustment from this table can be significant even if voltage is not all that low. For example, at 12.8 volts, 793.47uSec * 2 = 1586.94uSec (1.59ms) will be added. So at a BPW of 10.0ms and 12.8 volts, BPW will be increased 15.9%).

Thanks to RBob that the voltage generally perceived as "Battery Voltage" and as reported as such via most AUJP adx files is actually ignition voltage, or "keyed ignition voltage". The original GM calibration has Switch 16, bit 6=1 = use fuel pump voltage.

Dominic Sorresso

RBob made me aware of a similar calc for Inj. bias v Batt. In the LT-5 cal.
However, are u saying that the Batt v is only what is read by ECM at Ign On?
So PW is not modified based on a varying Batt V dynamically?

84Elky

Can't accurately answer because don't know your $mask (see PM sent). But am saying that in $8d AUJP, b6 of the flag at 0x0016 determines the voltage to be used for lookup in the voltage/injector PW adder table (1=use fuel pump voltage; 0=use keyed ignition voltage -- Voltage directly at the battery is not read by the ECM). Your $mask may be different from AUJP $8d, but most GMs follow a similar pattern.

RBob

iTrader: (1)

In the $D0 mask the ignition switch voltage is read 10 times a second. It is used for injector compensation among other things. There isn't an option to use the fuel pump voltage instead.

RBob.

Dominic Sorresso

Thanks RBob for the clarification. Any conjecture on why ignition switch and not fuel pump voltage? Is the diff inconsequential?

RBob

iTrader: (1)

I would want to use the voltage input that is closest to the actual voltage the injectors get. The IGN+ is likely a lot closer as that is what provides power to them. While the fuel pump voltage is rather remote from the injectors.

RBob.

84Elky

Thanks also RBob. My pump voltage is consistently 0.3 to 0.4 volts higher than keyed ignition. Could that be due to large wire to pump, smaller wire ignition to ECM. Would be interested in what others observe.

Dominic Sorresso

So 84Elky,

Is the value in the table the spec from the injector OEM or is it that value doubled? Based on what you outlined, it should be the OEM spec that then gets doubled in the calc. Correct?

Edit: In re-reading your post, it becomes clearer as to what it is. Just call me Homer. DOH!

Dominic Sorresso

Thought I would resurrect this thread and give an update. Although I still suspect that the IB is not dead on, I believe it to be much closer than what was used for the stock Bosch Injectors. The VE tables are smoother and no where as erratic as before with crazy ups and downs. All I can say is that the motor feels it responds so much better to slight movements of the throttle, and it does that in a very smooth way. Not sudden or choppy. It simply drives very smoothly. A stab of the throttle tho is immediate with no hesitation.
One other observation came from my washing the car and cleaning the exhaust tips. Before I would use chrome polisher to clean the tips (C6Z06 NPP controlled). They look a bit like over-sized Corsa tips.
Now I can wipe the exhaust w a wet cloth and clean them off. There is MUCH less soot on the tips after having tuned w the revised IB. So my question is, "Is this a good thing, OR does it indicate it is running lean?". My BLMs show it is running a tad lean but not by much and still w a rich/lean split between the two banks. IOW, they straddle 128 +/- 6.
Thoughts or comments appreciated.

Dominic Sorresso

OK. RE-resurrecting this thread. I was finally able to get more accurate Injector Bias for the Accel 150121. The ones which are published by Accel for the 24# are close. Lovely day today, so I put the old scantool on it to check BLMs using the new IB values. Just sat in garage at idle, going into C/L and LEARN mode.
L/R BLMs were 129/125. Very solid altho the R/S did drop a bit w increase in IAT but still in the +- 6 range for BLM. Also, WBO2 showed a tighter control over the AFR. Swings were much smaller. Waiting for chance to take it out.