WranglerFix PCM and HPTuners

[Steel City 06]

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.

I agree with using total fuel trims as the adjustment method.

As for adjusting injector PWM vs fuel mass, this is the correct method if the injectors actually have different flow rates (which is fairly likely). This is (normally) only adjusted by using a scalar factor, and it applies globally.

If there are correlations with RPM or pressure ratio, then those would be adjusted through the VE tables. However, simply swapping injectors will have near zero effect on actual volumetric efficiency, so the injector PWM to mass tables are the first thing to change.

 

[GoldenGorilla]

I'm using HPTuners with an 04 JTEC+ Rubi. I'm curious if my NGC3 bretheren have issues with odd stumbles between 2500-3200rpm when running VCM Scanner? It's like fuel or spark cuts out for a couple milliseconds, only while scanning on the USB cable. I can't ever find it in the logs though. Scanning with TDN doesn't do it but isn't helpful to me.

I've kicked up timing by 6-8 degrees at the kpa range correlated to WOT at my elevation ranges (5,000ft-12,000ft) and also found it improved power on the highway.

 

[Lemmy]

I'm using HPTuners with an 04 JTEC+ Rubi. I'm curious if my NGC3 bretheren have issues with odd stumbles between 2500-3200rpm when running VCM Scanner? It's like fuel or spark cuts out for a couple milliseconds, only while scanning on the USB cable. I can't ever find it in the logs though. Scanning with TDN doesn't do it but isn't helpful to me.

I've kicked up timing by 6-8 degrees at the kpa range correlated to WOT at my elevation ranges (5,000ft-12,000ft) and also found it improved power on the highway.

Yes, feels like a misfire or skipping under acceleration. Seems to be noise introduced by the HP tuner device. Interested to hear more about what changes in general bring some life to the 4.0
Maybe a topic for a separate thread.

 

[Juggernaut]

With an injector swap you should input the data from the manufacture’s data. Scaling should be a last resort. What is happening here is your applying a uniform correction to the new injector assuming the slope is identical to the original.

 

[Juggernaut]

Terry - have you created a graph with the x axis as rpm and y axis as pratio or map and actual seen a uniform 10% difference throughout the entire range due to the injector swap?

 

[TerryD]

With an injector swap you should input the data from the manufacture’s data. Scaling should be a last resort. What is happening here is your applying a uniform correction to the new injector assuming the slope is identical to the original.

These are rebuilt injectors from Precision Auto Injectors. I've emailed them to see if they have that information to make this less complicated.

Terry - have you created a graph with the x axis as rpm and y axis as pratio or map and actual seen a uniform 10% difference throughout the entire range due to the injector swap?

LTFT average for a 15min drive before changing the injector tables:

Here are the MIN values from that same log:

The "0.0" cells are from PE I believe.

I did not have HPT before I swapped the injectors but I did regularly watch my LTFTs with TorquePro on my cell phone and after the injector swap my LTFTs pretty much doubled across the board. I'm around 1300' elevation here so they should be in the 1-2% range regularly IMO. Seeing 5-10%, I believe we're getting more flow at the shorter PW.

The only mods to the Jeep are a cheap throttle body spacer that was on it when I bought it (and helped my intake tube clear the PCV vent line on the RENIX valve cover) and a full aFe 2.5" exhaust and cats (no header yet). Those were both before the injectors were installed.

 

[TerryD]

Well, I took a nice long drive today to pick up some stuff from town. Several hours of driving round trip between highway, interstate and plenty of in-town driving.

Just the 3 degree bump in timing has made a huge difference on the highway. It struggles so much less maintaining speed (50-70mph) and unlocked the torque converter noticeably less than before. I'm going to continue to drive it this week to let the ECM get settled in with my previous changes and give it a little broader range of weather (cooler morning OTW to work and higher ambient temp cold starts after work) and then next weekend I'll do some logging and see what changes I want to make.

A slightly lower RPM 4-3 shift is going to happen. There were still several instances where it unlocked the converter on the highway on hill climbs where it really should have gone to 3rd. I wish I could edit the TCC tables but hopefully someone will figure that out in the future. I'd like to get it to lock the TCC in 3rd on long climbs automatically but for now, I'll just have to get it as good as I can.

Gonna be some more studying!

 

[Juggernaut]

Change your y axis to pressure ratio to see the result of the injector change based upon engine load versus just the throttle position as you currently have it. Comparing by throttle position alone is not accurate because the load can vary at a given throttle position, ( think up hill vs. down hill without moving your foot). Try logging as I’ve described.

 

[TerryD]

Change your y axis to pressure ratio to see the result of the injector change based upon engine load versus just the throttle position as you currently have it. Comparing by throttle position alone is not accurate because the load can vary at a given throttle position, ( think up hill vs. down hill without moving your foot). Try logging as I’ve described.

Which "pressure ratio" do I need to use?

 

[Juggernaut]

Which "pressure ratio" do I need to use?

View attachment 631852

Try the first one under the volumetric efficiency tab. IIRC I may have defined my own which is Pratio= MAP/Baro.

 

[astjp2]

I miss the days of changing jets and secondary springs.... and maybe tweakin the distributor spring once in a while.

 

[TerryD]

Try the first one under the volumetric efficiency tab. IIRC I may have defined my own which is Pratio= MAP/Baro.

Would "engine load" not give you a similar table?

 

[Juggernaut]

Would "engine load" not give you a similar table?

No engine load is based off the MAP reading only.

 

[TerryD]

Try the first one under the volumetric efficiency tab. IIRC I may have defined my own which is Pratio= MAP/Baro.

That one works. Gonna run a log and then I'll post the table here.

 

[TerryD]

Here is the log from this evening and the table I built to log it. I had to compress them to ZIPs to get them to upload on this forum because its not an accepted file type.

 

[Juggernaut]

Here is the log from this evening and the table I built to log it. I had to compress them to ZIPs it to them it to upload on this forum because its not an accepted file type.

I couldn't open the second file, is this data on a stock tune? or does it include changes to the injector data?

 

[TerryD]

I couldn't open the second file, is this data on a stock tune? or does it include changes to the injector data?

The second file is the table I created in the logging software for the ratio VS rpm

 

[Juggernaut]

Based on the log, your trims are roughly 1%-7% over the operating range, with the greatest frequency in the 1-5% range. Also this data isn't filtered for deceleration. I don't know if this log is pre or post changing of injector data in HPT, but the same point is evident that you're not seeing a uniform 10% difference due to the injectors. You should also consider logging Bank 1 and 2 short and long term trims for comparison sake. As a rule of thumb +/- 5% is reasonable deviation, (you will never maintain "0" trim), and you will see a change day to day depending on conditions.

 

[TerryD]

Based on the log, your trims are roughly 1%-7% over the operating range, with the greatest frequency in the 1-5% range. Also this data isn't filtered for deceleration. I don't know if this log is pre or post changing of injector data in HPT, but the same point is evident that you're not seeing a uniform 10% difference due to the injectors. You should also consider logging Bank 1 and 2 short and long term trims for comparison sake. As a rule of thumb +/- 5% is reasonable deviation, (you will never maintain "0" trim), and you will see a change day to day depending on conditions.

That log is from yesterday evening. It has my altered injector trim data and a 3 deg timing bump over the original base table.

I understand I'll never get perfectly 0 on LTFT. I'm about 1200-1500' elevation in this area so slightly negative is what I would prefer.

I'm just trying to get back to the 3-5% negative trims I had before I swapped to the 4 hole injectors.

Can you log LTFT and STFT together in a single table? I'm at work so I can't see if there's a "total fuel trim" option in the menu.

 

[Juggernaut]

That log is from yesterday evening. It has my altered injector trim data and a 3 deg timing bump over the original base table.

I understand I'll never get perfectly 0 on LTFT. I'm about 1200-1500' elevation in this area so slightly negative is what I would prefer.

I'm just trying to get back to the 3-5% negative trims I had before I swapped to the 4 hole injectors.

Can you log LTFT and STFT together in a single table? I'm at work so I can't see if there's a "total fuel trim" option in the menu. Also, wouldn't logging with "engine load" rather than pressure ratio help with separating cruise, power and decel trims?

If you look in the pull down Tool menu under Math Parameters there is a fuel trims tab with combines trims separated by bank. Yes using pratio or map as an axis does allow you to identify areas of cruise, power decel, etc.. I mention decel because your DFCO is mostly likely still enabled which can skew things and you also have a few values around 10% + in these areas that I didn’t want to be confused in the conversation. If you log by bank you’ll see a variation between them.