JJ63

iTrader: (1)

Hello guys, I was hoping to a little more help. I think I'm almost finished with my tunes. Just a couple things I'm having trouble with.
1, There feels like a miss while I'm cruising and the tps is under 5. I'm thinking it's the tune as just a little gas and the miss goes away.
2. When I take let completely off on the gas, there is a couple lurches as if the pedal is tapped a couple times.

I attached my latest bin and a csv. The miss occurred at 6.25 and 7.17 engine run time. There are plenty of other times that the miss happens, these instances are just when I looked down and saw the exact time.

Thanks

SbFormula

For number #1, Mine does the same at feathered throttle on slow cruise (30-50 mph). I noticed it's when cruising around 2000 rpm or less. It's almost every time the engine has not enough load and the drivetrain starts getting loose type of thing. It feels like a miss but I believe it's not. Of course as soon as you give a tinny bit more throttle, it goes away (engine under more load) or over 2000 rpm. Could be too much SA, I don't know!

For number #2, have you checked SA on Decel? Also DECEL and DFCO. Your log is incomplete! There is no Injector BPW and FPW. Also your Ref-SA is weird not going over 13* despite your tables showing over 20* Do you have the .XDL file?

JJ63

iTrader: (1)

Thanks for replying.

Attached is the xdf. The extension has been changed to ecu so I could upload. I got rid of some values in my adx file to make it simpler to work with. Doesn't Ref-Sa value equal timing added to base. My base is at 15. Injector BPW is column "N". What tables should I change for decel? I have a 7730 ecm.

SbFormula

Yep you're right. Add your base to Ref-SA. Mine is Total SA so I don't have to do the math. Yep Colum N, I missed it

I'm not familiar with DECEL, I was just suggesting that could be something to look into.

I'm pretty sure I've read stuff on forums about engine surge on decel with EFI. Maybe you want to do some research in the forum (time consuming I know!)

DO YOU have your .xdl?

JJ63

iTrader: (1)

I ended up adding usec in the Injector pw correction if pw is under 3.90ms. It seems like both problems are fixed.

SbFormula

Interesting! Do you have a copy of your table, 0x40B? Mine was zeroed out like recommended on this site after I switched to Bosh III. I'm tempted to experiment now.
What kind of injectors do you have? Do you have the 7730 ecm speed density system?
Thanks

JJ63

iTrader: (1)

I have bosch III 36lb and it is 7730sd. I noticed that the miss was coming when injectore pw was under 1.40. Here is a cut & paste of my table:

320.435
213.623
152.588
137.329
91.553
61.035
45.776
15.259
0.000
0.000
0.000
0.000
0.000
0.000
0.000

SbFormula

Great Thanks!!! I don't go that low on BPW because I have 32lbs for a 383. But I'll keep an eye when datalogging and see what the BPW is when I feel the "miss"

SbFormula

Here's what I've got from FIC for the Bosh III datasheet. That's at 43.5psi:

BPW ... µsec
0.486 ... 328.4
0.729 ... 243.4
0.973 ... 175.8
1.216 ... 126.9
1.459 ... 102.4
1.702 ... 83.8
1.945 ... 74.4
2.188 ... 62.7

84Elky

FWIW ---
In full disclosure, I'm one of those who recommends zeroing the low PW table if exact (note "exact") values are not known from the injector manufacturer. Why? Because that addition without knowing what's happening under the covers is like throwing a dart while blindfolded. Ditto to a degree for voltage offsets. Both of these compensations do nothing more than add a respective PW to the calculated SD BPW.

Now to the real issue here: Single Fire (SF) Mode. By default, Factory $8d AUJP and S_AUJP have the following settings for SF:This means that any time BPW is between 0.855 and 1.1 ms, SF Mode will be invoked. On a modified engine with large injectors, this generally will mean there is too little fuel in this PW range for proper operation. Adjusting these values to invoke Single Fire at a higher PW solves the "stumble" issue because sufficient fuel is provided.

Looking at the log and bin provided in Post #1, these values have been changed to:Not sure the reason, but certainly limits SF Mode. But even with these settings, here are stats of being in SF Mode:Even with the above reduced SF mode PW values, the engine is in SF mode 3.2% of 2890+ samples at a median RPM of 2175.

IMO, what really should be done is to increase the SF mode Scalars to avoid SF Mode below a given PW. Not sure what that threshold is, but would seem to be a better approach than just throwing PW at a low value to compensate. Remember, Factory SF mode values are for a stock engine idling at say 500-600 RPM.

Regarding Decel (DFCO) in the discussion, there are MAP and TPS% Scalars that control when it's invoked and exited. During DFCO, SA-REF and PW will =0.

Elky

SbFormula

SbFormula

Just looking at OEM bins for 1991 LB9 (ATNX, AXXB, AXYC...) and it seems like MT's bins are set up with 0.763/0.793ms and AT's bins are 0.977/1.221ms. Looking at my own logs, I rarely hit the single fire mode (only on decel prior to DFCO or during slow shifting).

But it's something I will keep in mind.

If I understand correctly, the threshold is based on BPW and not corrected BPW. So adding PW won't prevent the single fire mode. However in single fire mode, we will get more PW with the adder.

84Elky

Not sure I exactly understand the question due to PW semantics, but see if this helps. There are really 3 pulse widths:Here's order of activity to create Final PW beginning with CL o2 corrected PW (if OL, then begin with SD PW):So yes, adding PW if PW is low won't prevent SF and yes, will get more PW with the low PW adder. But a few things to consider:Maybe it's just me, but I don't want an arbitrary addition of fuel unless I'm using the low PW table to tune idle with a WB, which I guess is an option -- just one I choose to avoid.

Use of Low PW is like whether one chooses to use the PE spark adder table. I personally choose to zero that table and tune using only the main spark tables. Guess in all of this, that's why there's chocolate and vanilla ice cream .

JJ63

iTrader: (1)

Ok, I upped 0x3ED Invoke SF from 0.763ms to .855 and 0x3EB Disable SF from 0.8ms to 1.4. .855 is a 5.7tpi figure amd 1.4 is where I've noticed a miss under that figure. SO, it did run smoother on my quick drive to work. I also lowered the under 3.90 table back to stock. Thanks.

SbFormula

Excellent thanks!