I am trying to understand why my injector pulse width is decreasing when PE is calling for more fuel. Moved PE vs RPM quite a bit without seeing a change in the WB. TunerPro xdl attached.

Edit: found this, might be my issue but have never successfully changed anything in hex editor with tuner pro.
https://www.thirdgen.org/forums/diy-prom/496597-injector-pw-stopping-why.html

 

What's your set-up?

MAF $6E?
MAP $8D?

 

I figured out you had a MAF $6E

I don't see anything wrong. I assume as the rpm increases, VE decreases. You would see that with LV8 data, but it's maxed out at 255 from 3755 to 4650 rpm, then starts decreasing indicating decrease in VE. As RPM increases, total air per sec. (MAF) increases but total air per each cylinder intake cycle decreases, thus less gas is needed per each revolution.

When you change PE AFR vs RPM, you should see Commanded PE AFR change too. In your log it's at 11.13. If you make changes to PE AFR vs RPM, this should change +/- depending on what you did. If PE AFR does not change, WB AFR won't change either! Make sure your tune gets uploaded correctly.

BTW, your BLM is at 144 when in PE. Means your tune is lean. If you commanded 11.13 AFR in PE what was the WB gauge displaying? BLM 144, means 12% was added to the INJ PW. What is your injector size?

Also, your SA is at 25* total in PE, seems low, but again, I have no clue what set-up you have since you did not mention anything about your car, engine, induction etc..

And... knock retard of 7.8* at some point which gives you an effective SA of 17.2*.

This engine needs tuning for sure.

 

Just noticed my signature wasn't populating so no engine info, sorry about that.
1985 vette w/165 running $6e, 383, 58mm tb, AS&M runners, heavily ported lower, 185 aluminum heads, comp 250-3 cam, 1.5 rockers. Engine dyno with a carb was 455hp/480tq,31lb injectors


In trying to move the AFR I had moved both the PE vs coolant and PE vs rpm over the course of many tunes to be 100% with little change to the >3500 area. My last tune before this one was commanding a 6.02 AFR/ I was just trying to see movement in PE after 3500. It created other issues but a similar response in BPW. As far as SA, I agree that it is pretty low and believe it may be false knock I am seeing but was hesitant to put timing back without seeing sub 13 AFR all the way through WOT.

I did figure out how to modify the HEX from the post referenced above late last night but haven't been able to test yet. Also if you are using the $6e expanded my WB is in the log.

 

You should get around 420hp/+500tq with AS&M TPI, peak at lower RPM.

I'm not sure I understand correctly. Are you trying to move commanded PE AFR or WB Gauge AFR? When you say, little change to the over 3500, what change are you talking about? Commanded AFR or WB Gauge AFR? The INJ BPW will definitely get lower once you pass peak torque RPM. Less air in cylinder per each intake stroke. Normal pattern for TPI intake as volumetric efficiency (VE) plummets early in RPM range. Also, if locked BLM varies during PE, it could affect WB Gauge AFR everything else being equal. I usually reprogram BLM boundaries to isolate PE MAF/RPM range so BLM stays at 128.

What is fuel pressure at WOT (no vacuum)?

 

I was trying to move the WB AFR, it is steady above 13.** on the WB from 3000 ish rpm and up no matter how much PE I added. That's when I threw 100% in both PE tables to see if it moved the AFR, see the datalog I attached in the last post. It did not. That is when I noticed the BPW. I was looking to see if I was running out of fuel pump or injector so wanted to calculate Duty cycle. With a commanded afr of 6 and only getting to 13.** on the WB in the upper RPM area I figured I was running out of fuel. I was surprised to see pulse width drop when not anywhere near commanded.

31lbs 40 psi at idle with vac unhooked. Dont know WOT, was on my list of troubleshooting until I noticed the injectors not trying any harder.

 

OK!!

On your log, I have:
Commanded PE AFR at 11.13
BLM will vary from 138, 142 and 144 in PE events
Voltage is constant (good!)

The BLM varying like that makes it hard to compare log to log. You might increase Commanded PE AFR but BLM gets locked lower, let's say 130. That will yield a 10% decrease in calculated INJ BPW. You need to stabilise the BLM by changing the BLM boundaries in the tune so cell 12-13-14-15 are dedicated to WOT. Something like MAF over 160 for example. That way, BLM will stay at 128. By doing so, the real AFR gauge will get leaner, so you need to increase PE AFR to compensate. That is the first step.

There is a peak in your log at 5175rpm / MAF 252.64 / AFR at 11.13 which yields 9.72ms of INJ BPW before voltage compensation. That is around 85% INJ DC if I estimate voltage compensation.O2 sensor voltage indicates 759mv which is consistent with a real AFR of over 13.xx. That means, according to my calculation, you would need to add around 5% more fuel to get under 13.xx. That would give you close to 90% INJ DC. In this specific case, that means a commanded PE AFR of 10.5 instead of 11.13. So, you are definitely not running out of fuel right now.

Now that is at 5175 RPM! Your engine can rev more with your set-up. So at 6000rpm, you will definitely run over 90% INJ DC. Something to keep in mind. I don't know what fuel pressure you are running, but there is a way to increase INJ flow rate by increasing fuel pressure. I assume your 31 injectors are rated at 43.5lbs of fuel pressure. I don't have the formula off hand.

The way I see it, you are in a classic case of maxing out the $6E MAF tables when in WOT. So the only way to compensate is by tuning PE AFR at different RPM.

Good luck

 

FYI:

PE AFR = Commanded AFR / (1 + %Change vs Cool/100 + %Change vs RPM/100)
Suppose Commanded AFR is 14.7
For the selected RPM, suppose the percent change to Fuel/Air Ratio from the MAP table is = 3.9 and the percent change to Fuel/Air Ratio from the COOLANT table at the selected coolant temperature is = 18.0, then the approximate PE AFR would be: 14.7 / (1+0.18+0.039) = 12.1:1 AFR

The Fuel/Air Ratio from the MAP table data can be entered in negative.

A way to estimate real AFR with O2 sensor mv. Not exact but ball park.
830 mv = 13.0:1
880 mv = 12.5:1
930 mv = 12.0:1

 

Found the formula

[Advertised Flow Rate] X [The Square Root of (Your Pressure ÷ Rated Pressure)]

For example, what happens to the output of a 31 lbs./hr. injector rated at 43.5 psi. if you run it at 50 psi.?

50 ÷ 43.5 = 1.149

√ 1.149 = 1.072

31 X 1.072 = 33.24 lbs./hr.

Means you would have to change INJ Flow rate in tune from 31 to 33.

 

Thanks for all of the help. These are the pieces of the puzzle I am missing. Locking the BLM's is something I haven't done yet. Might need a bit of direction there but I will give it a shot while I am on lunch.

Here is my injector data. I have room to grow but will have to improve the fuel pump to get to the higher pressures.

 

Ok, could use some help. Here is what I am looking at, what should I be changing to lock the BLM's as you described. Wasn't immediately apparent.

 

Well that's not 31 lol!!!

 

Push "BLM Cell Airflow Boundary #3" to 160 and see what happens on the datalog. Now be careful, it will lean out your WOT while in PE, so make sure you adjust PE AFR to at least 10 from 11.13

Let me refer you to @Tuned Performance for any other questions. Actually, he can tune your engine for a fee. It's all worth it instead of the head aches and tons of hours of researching and asking questions

Cheers

 

I will do that thanks!!

 

31 @40 psi

 

Ummm, allow me to be more specific. Your specs says 32.97 @ 42.5, which I find weird but it is what it is.

So at 40, we get:
40 ÷ 42.5 = 0.9411
√ 0.9411 = 0.9701
32.97 X 0.9701 = 31.98 lbs./hr.

Now if the 42.5 is a typo which in reality is 43.5, we get:
40 ÷ 43.5 = 0.9195
√ 0.9195 = 0.9589
32.97 X 0.9589 = 31.61 lbs./hr.

 

LOL. Didint even catch it.....3 bar is 43.5, has to be a typo

 

What do you have in your tune?
31.6?

 

31.02 but that was from the 42.5. I will bump it up to 31.6. If I understand correctly that will make my maf tables a bit leaner?

 

Nope! Not the MAF tables. It will reduce the INJ BPW by about 1.5%, so yes you will get leaner a bit.

INJ PBW calculation:

MAF, RPM, AFR & INJ Flow Rate

(((((MAF/8)/(RPM/60))*2)/AFR) / ((Inj Flow Rate A/60/60)*1000/2.20462) ) * 1000/2

Followed by INT and BLM correction

So if INJ Flow Rate is augmented, INJ PBW is diminished, everything else being equal. Makes sense. A bigger injector needs to open less to provide same amount of fuel.

 

I appreciate it. Your replies are filling in the gaps in my knowledge. I came home and went back to a tune that was good in cruise and datalogged it again. Needed a reference point to start with changes you have given me. Turns out I was making headway on PE and it matched the log from the first time running that tune. Either way I will start from here and see where it goes.