WranglerFix PCM and HPTuners

[Steel City 06]

I don't see any 3D PWM tables? Are the 2D tables listed as PW VS Fuel Mass and vice-versa the correct tables?

View attachment 631363


View attachment 631364

That's correct. Also use the factor on the offset, the min PWM, and the startup scalar. (Don't use it on the multipliers)

Basically you want everything to be cleanly scaled with the new factor. Note that in some cases you'll be multiplying by 0.9 and in others dividing

 

[Juggernaut]

I find it hard to believe that a change to 4 hole injectors resulted in a consistent 10% increase in fueling through the entire pressure and rpm range, requiring a change to the injector data. Terry if your monitoring ltft+stft are you seeing negative 10’s everywhere or just in a specific range? Changing injector data is a global change and in essence is saying that the 4 hole injectors are delivering a greater fuel mass for a given pulse width, and actual delivering a greater flow rating than the stock injector, rather than a change in spray pattern or atomization.

 

[TerryD]

That's correct. Also use the factor on the offset, the min PWM, and the startup scalar. (Don't use it on the multipliers)

Basically you want everything to be cleanly scaled with the new factor. Note that in some cases you'll be multiplying by 0.9 and in others dividing

OK. Maybe it's because eive been drinking all day and maybe because I'm a moron.

Can you explain how to apply 3D log data offsets to a 2d table?

 

[Steel City 06]

OK. Maybe it's because eive been drinking all day and maybe because I'm a moron.

Can you explain how to apply 3D log data offsets to a 2d table?

You don't need to, unless you're trying to tune VE separately.

The PWM values simply tell the computer how much fuel it is putting in at a given PWM value. The idea is to get this as close as possible to keep your overall LTFTs close to zero, at least on average.

VE tuning comes in if you have effects from changes like adding a Windstar intake or new manifolds. It shouldn't be used to make global changes unless there is actually something causing more (or less) air to make it into the engine (e.g., turbocharger). Local changes will indeed be made through the VE tables.

Since you have used new injectors and noticed significant changes, it is more likely that the injectors don't have the same characteristics as the old ones than having a change in air charge.

In short, you want to keep the fuel and air mass as accurate as possible because it is also used for downstream calculations, such as for emissions.

A crude way to think of my method is to use the injector PWM as a sort of coarse/global adjustment to fueling, and the VE tables for fine tuning. That isn't exactly what we are trying to achieve, but in practice it gets us close enough

 

[TerryD]

You don't need to, unless you're trying to tune VE separately.

The PWM values simply tell the computer how much fuel it is putting in at a given PWM value. The idea is to get this as close as possible to keep your overall LTFTs close to zero, at least on average.

VE tuning comes in if you have effects from changes like adding a Windstar intake or new manifolds. It shouldn't be used to make global changes unless there is actually something causing more (or less) air to make it into the engine (e.g., turbocharger). Local changes will indeed be made through the VE tables.

Since you have used new injectors and noticed significant changes, it is more likely that the injectors don't have the same characteristics as the old ones than having a change in air charge.

In short, you want to keep the fuel and air mass as accurate as possible because it is also used for downstream calculations, such as for emissions.

A crude way to think of my method is to use the injector PWM as a sort of coarse/global adjustment to fueling, and the VE tables for fine tuning. That isn't exactly what we are trying to achieve, but in practice it gets us close enough

So I'm looking at a PWM table that read out my fuel mass based on the ms the injectors are open.

Do I multiply this by 0.97 to get my 3% reduction in LTFTs because it's flowing roughly 3% more fuel for a given pulse width than the original injectors?

Then I need to multiply the inverse table by 1.03 to get a similar change?

 

[Steel City 06]

Correct, though make sure you're as close to exact as possible with the inverse. If it's slightly off it could cause issues.

So if you're going for a 3% adjustment, use 0.9700 and 1/0.97 (or about 1.0309) as your multipliers.

In my case my new injectors (12-hole) were flowing almost exactly 33% more than stock, causing the fuel trims to go so far off as to throw a CEL. So I used the factors 0.7500 and 1.3333 respectively.

 

[TerryD]

https://forum.hptuners.com/showthre...out-of-PCM-but-can-t-write-Erase-Failed/page2

I read about this. However, after successfully reading the ECM before breakfast I attempted a write this evening, bumping the entire base timing table by 3deg.

It erased and wrote to the ECM without issue. I'm thinking it was low resting battery voltage that was the culprit. I did a maintenance charge on the battery today while doing an engine oil/filter and front diff cover/fluid change.

The bump in timing made a notable difference in cruising power on the interstate. Nothing incredible but it held 4th with the converter locked on a shirt climb that usually, at the minimum, unlocked the converter.

 

[TerryD]

Correct, though make sure you're as close to exact as possible with the inverse. If it's slightly off it could cause issues.

So if you're going for a 3% adjustment, use 0.9700 and 1/0.97 (or about 1.0309) as your multipliers.

In my case my new injectors (12-hole) were flowing almost exactly 33% more than stock, causing the fuel trims to go so far off as to throw a CEL. So I used the factors 0.7500 and 1.3333 respectively.

Would doing the corrections in excel and pasting back be a more precise way? Seems HPT doesn't make super small multiplication changes.

 

[Steel City 06]

Would doing the corrections in excel and pasting back be a more precise way? Seems HPT doesn't make super small multiplication changes.

Yes, that can be easier. HP Tuners will round things for you (sometimes in apparently odd ways) as the actual hexadecimal code used to program the PCM doesn't always have the same level of precision as the decimal (human-friendly) translation shown in HP Tuners.

 

[TerryD]

Also, WHY DOES CHRYSLER PUT TWO FUCKING SCALES FOR THE SAME REFERENCE IN THE ECM?!? Grrrrr.....

This is why GM was the go-to end-user programmed fuel injection since the 80s.....

/rant

 

[TerryD]

OK. Altered the PWM tables and wrote to the ECM ONLY. Restarted just fine. Gonna unhook battery for 10min to reset the LTFT tables and then test drive and see what kinda mess I made. LOL

 

[Steel City 06]

OK. Altered the PWM tables and wrote to the ECM ONLY. Restarted just fine. Gonna unhook battery for 10min to reset the LTFT tables and then test drive and see what kinda mess I made. LOL

Pretty much the only change will be shifted STFT and LTFT values.

Furl economy and power will be a bit off for the first few drive cycles as the PCM relearns the fuel tables. But it should come back fairly quickly.

 

[TerryD]

Pretty much the only change will be shifted STFT and LTFT values.

Furl economy and power will be a bit off for the first few drive cycles as the PCM relearns the fuel tables. But it should come back fairly quickly.

That's what I'm hoping. Did an excel comparison of my timing advance from before I made any changes to the latest tune with the 3deg timing bump and adjusted PWM tables. Looks like I gained 1-3deg throughout the table. I need a longer drive with more averaging VS the original to really compare.

Also, am I thinking right in that the "min inj pw" being 0.5ms means altering any part of the PWM tables with less than 0.5ms doesn't affect anything since that's the minimum time the ECM will attempt to open the injectors?

 

[Wranglerfix]

I read about this. However, after successfully reading the ECM before breakfast I attempted a write this evening, bumping the entire base timing table by 3deg.

It erased and wrote to the ECM without issue. I'm thinking it was low resting battery voltage that was the culprit. I did a maintenance charge on the battery today while doing an engine oil/filter and front diff cover/fluid change.

The bump in timing made a notable difference in cruising power on the interstate. Nothing incredible but it held 4th with the converter locked on a shirt climb that usually, at the minimum, unlocked the converter.

@Terry D

I have an idea for you. Please call me at 866-888-7710 whenever you get a chance.

Mark

 

[Steel City 06]

That's what I'm hoping. Did an excel comparison of my timing advance from before I made any changes to the latest tune with the 3deg timing bump and adjusted PWM tables. Looks like I gained 1-3deg throughout the table. I need a longer drive with more averaging VS the original to really compare.

Also, am I thinking right in that the "min inj pw" being 0.5ms means altering any part of the PWM tables with less than 0.5ms doesn't affect anything since that's the minimum time the ECM will attempt to open the injectors?

Pretty much. I did scale my 0.5ms factor, but your change is so small that I wouldn't think it would matter.

Be sure to scale the startup tables as well (if you haven't already) since the injectors are putting more fuel in than needed. Not a big deal (especially with your small adjustment) but sending unburnt fuel to the cats, especially if they're already hot, can shorten their lifespan.

In regards to timing, I also added a few degrees of advance to the cranking spark tables for a faster start. (I do have a faster aftermarket starter as well so my cranking RPM is higher than normal.)

My tune is based on a @Flyin' Ryan Performance canned tune so unfortunately I can't share my main spark tables. However I will say his tune is a very good starting point if you are willing to pay. There are a few additional changes I made since his tune though.

 

[TerryD]

Pretty much. I did scale my 0.5ms factor, but your change is so small that I wouldn't think it would matter.

Be sure to scale the startup tables as well (if you haven't already) since the injectors are putting more fuel in than needed. Not a big deal (especially with your small adjustment) but sending unburnt fuel to the cats, especially if they're already hot, can shorten their lifespan.

In regards to timing, I also added a few degrees of advance to the cranking spark tables for a faster start. (I do have a faster aftermarket starter as well so my cranking RPM is higher than normal.)

My tune is based on a @Flyin' Ryan Performance canned tune so unfortunately I can't share my main spark tables. However I will say his tune is a very good starting point if you are willing to pay. There are a few additional changes I made since his tune though.

Working on that adjustment right now.

I'm looking for the cranking spark tables now.

 

[TerryD]

Is this the correct field? How much of an increase have you used?

 

[Steel City 06]

View attachment 631592

Is this the correct field? How much of an increase have you used?

There's a separate field for cranking spark advance, I think for hot and cold. I added about 4° to each. Not at all necessary, just something I was messing around with.

Idle spark advance I also did mess with as well. You can get a much more efficient idle at 20° advance than 10-14°, but there is an increasing risk of stalling as you are eating into the torque reserve margin.

 

[TerryD]

I find it hard to believe that a change to 4 hole injectors resulted in a consistent 10% increase in fueling through the entire pressure and rpm range, requiring a change to the injector data. Terry if your monitoring ltft+stft are you seeing negative 10’s everywhere or just in a specific range? Changing injector data is a global change and in essence is saying that the 4 hole injectors are delivering a greater fuel mass for a given pulse width, and actual delivering a greater flow rating than the stock injector, rather than a change in spray pattern or atomization.

I'm monitoring only LTFTs to make these decisions. I'm also logging for drives where I try to hit the cells as many times as I can during the drive to get a good average of the LTFT for that cell (RPM vs MAP) to see. Without a readout on the pulse width, I have no way to really knowing where in the pulse ranges flowing better. I assume that it's the lower pulse widths as the higher RPM and load cells are reporting lower LTFT than where the engine spends the most of it's time.

This could also be a function of the engine not being in those ranges often enough to make adjustments. I'm going to drive it for a week then log for a nice long drive next weekend before I make any more fueling changes. So far I've seen a nearly 2% drop in LTFT in the lower RPM/Load part of the table with the change to the fueling tables I've made.

 

[Juggernaut]

I'm monitoring only LTFTs to make these decisions. I'm also logging for drives where I try to hit the cells as many times as I can during the drive to get a good average of the LTFT for that cell (RPM vs MAP) to see. Without a readout on the pulse width, I have no way to really knowing where in the pulse ranges flowing better. I assume that it's the lower pulse widths as the higher RPM and load cells are reporting lower LTFT than where the engine spends the most of it's time.

This could also be a function of the engine not being in those ranges often enough to make adjustments. I'm going to drive it for a week then log for a nice long drive next weekend before I make any more fueling changes. So far I've seen a nearly 2% drop in LTFT in the lower RPM/Load part of the table with the change to the fueling tables I've made.

Use the pre defined math of LTFT+ STFT creating a chart to speed up the process You can also create a chart of pulse width and fuel mass and adjust injectors based upon that but i disagree with adjusting your injector data.