Help understanding what is going on with Supercharged Jeep JK with 3.8l

[nwdean]

Hey folks,

I'm new to learning this stuff and trying to figure out what is going on with my Supercharged Jeep JK with the 3.8 in it. It seems like the PCM is trying to remove fuel even when it is lean. Not sure why, seems to be opposite of everything I have been reading up on. I added a wideband so I could see the exact numbers and was able to add it as a PID in the CAN BUS system so I could log it. I was able to check that the wideband and the narrowband O2 sensors are agreeing with each other around a 14.7 stoich. I work in cyber security with a background in forensics and hacking so I was able to figure out enough to get things logged and understand basic fueling concepts but that is about where I am at now. Any help is much appreciated.

Hardware:
- RIPP kit with high altitude pulley
- 180 degree thermostat
- plugs gapped to .30, NGK 4306
- fuel pump pressure is holding between 56-58 for this logging session (I have another standalone gauge for that but I watch it while I am driving)
- compression and leakdown numbers are in excellent shape
- injectors are Bosch 0280156127 (recently flow tested and they are literally in perfect condition and perfectly matched)
- MAP sensor is a Mopar 05033224AB (came with the kit)

Here is what I am seeing and I am attaching the logs and tune file:
Fuel Trim and AFR graph.png

[B00STJUNKY]

Hey folks,

I'm new to learning this stuff and trying to figure out what is going on with my Supercharged Jeep JK with the 3.8 in it. It seems like the PCM is trying to remove fuel even when it is lean. Not sure why, seems to be opposite of everything I have been reading up on. I added a wideband so I could see the exact numbers and was able to add it as a PID in the CAN BUS system so I could log it. I was able to check that the wideband and the narrowband O2 sensors are agreeing with each other around a 14.7 stoich. I work in cyber security with a background in forensics and hacking so I was able to figure out enough to get things logged and understand basic fueling concepts but that is about where I am at now. Any help is much appreciated.

Hardware:
- RIPP kit with high altitude pulley
- 180 degree thermostat
- plugs gapped to .30, NGK 4306
- fuel pump pressure is holding between 56-58 for this logging session (I have another standalone gauge for that but I watch it while I am driving)
- compression and leakdown numbers are in excellent shape
- injectors are Bosch 0280156127 (recently flow tested and they are literally in perfect condition and perfectly matched)
- MAP sensor is a Mopar 05033224AB (came with the kit)

Here is what I am seeing and I am attaching the logs and tune file:
Fuel Trim and AFR graph.png

A quick glance at your log shows that the PCM is reacting exactly as one would expect it to react in closed loop mode. You will not achieve an AFR outside of stoich (other than temporary deviations from stoich as STFT and LTFT react to bring it back to stoich when VE is not optimized at any given point in the calibration) until you enter Power Enrichment mode, which will put the PCM into open loop operation.

The entirety of your log has you in Closed Loop operation, and this is expected given that you never meet or exceed the WOT threshold voltage in order to enter Power Enrichment mode (which, you aren't logging TPS voltage, only percentage - but one can estimate your TPS voltage at a TPS% of 40 would be in the neighborhood of 2.0 volts - your WOT threshold voltage value is set to 3.0 volts).

You are seeing large negative fuel trims when you reach and exceed a pressure ratio around 1.0 which means that, for stoich fueling, either your VE values in those pressure ratio ranges are improperly calibrated, or your injector data (possibly a combination of both VE and injector data) is not properly calibrated.

Given the state of your VE table and the fact that you're seeing such negative fuel trims in the 1.0 pressure ratio range where your VE values are at least reasonable, though likely not quite accurate (and your VE only becomes considerably higher - unreasonably so - as Pressure Ratio increases), it would be expected that if you went WOT at around 3000 RPM, you'd see some extremely rich AFRs once P-Ratio reached and exceeded 1.17.

I'm not sure where you got your injector data from, but it's not a very good idea to only have it defined out to 9 milliseconds. You were reaching injector pulsewidths in excess of 9.2 milliseconds at a mere 40% throttle. And while the PCM will extrapolate past what you have defined, the data goes static past your last defined point, even if the actual flow characteristics dynamically change past that point. Needless to say, your injector data needs some attention as well.

Now, if you are wanting to achieve AFRs richer than stoich when hitting positive manifold pressure regardless of pedal/throttle position, you're going to need to run in open loop at all times (disable the o2 sensors) so that you don't have the closed loop feedback system reigning you back into stoich fueling conditions. The alternative could be to set the WOT throttle threshold value low enough that it puts you into Power Enrichment at relatively light throttle positions where you are still getting positive manifold pressure.

Another thing to consider is that your minimum spark maps are set to 10* timing advance at higher load and RPM ranges, about the same as your base table for PT and in some cases greater than what's defined in your WOT table. The issue with that is if you run into spark knock, the PCM isn't going to be able to decrease timing to anything lower than what's defined in the minimum tables, which could cause a snowball effect where a prolonged knock condition becomes worse and worse until it becomes pre-ignition and destroys your engine.

A lot of things that need addressed, my friend.

[GHuggins]

What appears to be going on is fueling is just out that much as it's not commanding PE yet as represented by the commanded lambda 1. I'm attaching a tune you can try - have no idea if it's actually going to help any as some of the tables I was looking for such as load/torque to enter PE weren't there. This one is just different throttle flow values that should be more in line with what the engine should be seeing. If it doesn't work or help any you'll need to log throttle voltage and adjust your PE setting accordingly for when you want it to go into PE... Just go easy and see if it's going into PE any better or not with this one and then of course you'll want to address the aforementioned items as well.

[nwdean]

A quick glance at your log shows that the PCM is reacting exactly as one would expect it to react in closed loop mode. You will not achieve an AFR outside of stoich (other than temporary deviations from stoich as STFT and LTFT react to bring it back to stoich when VE is not optimized at any given point in the calibration) until you enter Power Enrichment mode, which will put the PCM into open loop operation.

The entirety of your log has you in Closed Loop operation, and this is expected given that you never meet or exceed the WOT threshold voltage in order to enter Power Enrichment mode (which, you aren't logging TPS voltage, only percentage - but one can estimate your TPS voltage at a TPS% of 40 would be in the neighborhood of 2.0 volts - your WOT threshold voltage value is set to 3.0 volts).

You are seeing large negative fuel trims when you reach and exceed a pressure ratio around 1.0 which means that, for stoich fueling, either your VE values in those pressure ratio ranges are improperly calibrated, or your injector data (possibly a combination of both VE and injector data) is not properly calibrated.

Given the state of your VE table and the fact that you're seeing such negative fuel trims in the 1.0 pressure ratio range where your VE values are at least reasonable, though likely not quite accurate (and your VE only becomes considerably higher - unreasonably so - as Pressure Ratio increases), it would be expected that if you went WOT at around 3000 RPM, you'd see some extremely rich AFRs once P-Ratio reached and exceeded 1.17.

I'm not sure where you got your injector data from, but it's not a very good idea to only have it defined out to 9 milliseconds. You were reaching injector pulsewidths in excess of 9.2 milliseconds at a mere 40% throttle. And while the PCM will extrapolate past what you have defined, the data goes static past your last defined point, even if the actual flow characteristics dynamically change past that point. Needless to say, your injector data needs some attention as well.

Now, if you are wanting to achieve AFRs richer than stoich when hitting positive manifold pressure regardless of pedal/throttle position, you're going to need to run in open loop at all times (disable the o2 sensors) so that you don't have the closed loop feedback system reigning you back into stoich fueling conditions. The alternative could be to set the WOT throttle threshold value low enough that it puts you into Power Enrichment at relatively light throttle positions where you are still getting positive manifold pressure.

Another thing to consider is that your minimum spark maps are set to 10* timing advance at higher load and RPM ranges, about the same as your base table for PT and in some cases greater than what's defined in your WOT table. The issue with that is if you run into spark knock, the PCM isn't going to be able to decrease timing to anything lower than what's defined in the minimum tables, which could cause a snowball effect where a prolonged knock condition becomes worse and worse until it becomes pre-ignition and destroys your engine.

A lot of things that need addressed, my friend.

I paid a local tuner a significant amount of money to tune this for me and it has been "street tuned" to get to this tune right here. I have taken it to the dyno twice and each time they have told me I have hardware issues that are preventing them from doing anything further. Specifically that the fuel pump is not strong enough because it falls to 39 PSI. But the confusing part about that is that from what I can tell these specific injectors can fuel up to 350 hp for a forced induction engine at specifically 39 PSI. This only put out 220 at at the dyno and I wouldn't be looking for anything over 280 hp for this application. I just want to be able to pull a trailer up mountains behind the Jeep and have some more power on inclines when off-roading, but also staying as safe as possible.

Mainly I am posting this to figure out if this is a software issue or a hardware issue. And yes I have brought up my concerns to the tuner, I just keep getting told my Jeep is broken. They said they only care about LT fuel trims for anything under WOT driving, but that does not seem right to me. That is why I went to the trouble if integrating the wideband, for data and safety because this is my only vehicle. I am at a loss.

I really appreciate your reply and I will be doing more research on the things you mentioned.


***also to add that fall in pressure is only above 4600 RPM, before that it stays well above 50 PSI until around 4300 or so

[nwdean]

What appears to be going on is fueling is just out that much as it's not commanding PE yet as represented by the commanded lambda 1. I'm attaching a tune you can try - have no idea if it's actually going to help any as some of the tables I was looking for such as load/torque to enter PE weren't there. This one is just different throttle flow values that should be more in line with what the engine should be seeing. If it doesn't work or help any you'll need to log throttle voltage and adjust your PE setting accordingly for when you want it to go into PE... Just go easy and see if it's going into PE any better or not with this one and then of course you'll want to address the aforementioned items as well.

Thank you for this, I will try out that file AND I can easily log this again and add Pedal Voltage to the datalog

[B00STJUNKY]

I paid a local tuner a significant amount of money to tune this for me and it has been "street tuned" to get to this tune right here. I have taken it to the dyno twice and each time they have told me I have hardware issues that are preventing them from doing anything further. Specifically that the fuel pump is not strong enough because it falls to 39 PSI. But the confusing part about that is that from what I can tell these specific injectors can fuel up to 350 hp for a forced induction engine at specifically 39 PSI. This only put out 220 at at the dyno and I wouldn't be looking for anything over 280 hp for this application. I just want to be able to pull a trailer up mountains behind the Jeep and have some more power on inclines when off-roading, but also staying as safe as possible.

Mainly I am posting this to figure out if this is a software issue or a hardware issue. And yes I have brought up my concerns to the tuner, I just keep getting told my Jeep is broken. They said they only care about LT fuel trims for anything under WOT driving, but that does not seem right to me. That is why I went to the trouble if integrating the wideband, for data and safety because this is my only vehicle. I am at a loss.

I really appreciate your reply and I will be doing more research on the things you mentioned.


***also to add that fall in pressure is only above 4600 RPM, before that it stays well above 50 PSI until around 4300 or so

There may very well be a hardware issue with your fuel pump. But even if there wasn't, this isn't a tune I would be proud of calling my own. That's for damn certain.

[nwdean]

There may very well be a hardware issue with your fuel pump. But even if there wasn't, this isn't a tune I would be proud of calling my own. That's for damn certain.

Yeah I am nervous because I do not want to damage my vehicle. I do have a boost-a-pump kit in a box sitting in my office, but wanted to get more info if it was necessary or not. I had contacted RIPP about the fuel pump and they said they have never heard of any of their thousands of customers having to upgrade that for their kits because it was a mild amount of boost and the stock pump could handle from their experience. In fact nobody seems to make an upgraded fuel pump for that vehicle at all.

I guess I need to figure out my options and next steps on all fronts and figure out how to have a reliable vehicle again. This really sucks. Thank you for your info and time.

[GHuggins]

To better show what BoostJunky is talking about this is a stock high altitude tune for a magnuson blower. Granted it's for a 3.6, but same rules apply... You can change cam tables for super sensitive throttle reactions or leave stock to be a daily driver that only has umph with wot..... Not sure what injectors magnuson gives out with their kits as it's been a long time since doing one - you might even want to get another set with actual dodge data to input in yourself.

After tuning these put down around 330 to the tires - 3.6's with high altitude kits.

[nwdean]

To better show what BoostJunky is talking about this is a stock high altitude tune for a magnuson blower. Granted it's for a 3.6, but same rules apply... You can change cam tables for super sensitive throttle reactions or leave stock to be a daily driver that only has umph with wot..... Not sure what injectors magnuson gives out with their kits as it's been a long time since doing one - you might even want to get another set with actual dodge data to input in yourself.

After tuning these put down around 330 to the tires - 3.6's with high altitude kits.

Would this also apply to a centrifugal blower? I know they function differently than the type magnuson makes.

[GHuggins]

That tune was meant to help illustrate what boostjunky was talking about with the fueling settings. The blowers operate differently, but both still make boost - just at different areas. AND yes, anything is possible with a fuel pump - it may have been going bad before the blower install and you just didn't realize it?

[nwdean]

That tune was meant to help illustrate what boostjunky was talking about with the fueling settings. The blowers operate differently, but both still make boost - just at different areas.

ok cool, understood. So this is more for the concept and I should not directly apply that to my vehicle?

[nwdean]

That tune was meant to help illustrate what boostjunky was talking about with the fueling settings. The blowers operate differently, but both still make boost - just at different areas. AND yes, anything is possible with a fuel pump - it may have been going bad before the blower install and you just didn't realize it?

Oh and sorry forgot to mention one more thing, it is a brand new fuel pump and the stock spec for it is 58 PSI and it holds that within 5 PSI until about 4500 RPM at WOT from my recent driving tests. Redline is 5500 for these engines and frankly I very rarely bring it above 4500 because it's a lifted Jeep, not really much fun to drive fast lol

[B00STJUNKY]

I usually like to have injector data plotted out to at least 40 milliseconds, as that would be 100% duty cycle at 3000 RPM (unlikely to require that kind of range at such a low RPM in most setups, but not impossible with low revving, mid-range power setups).

At 6000 RPM, you only have a window of 20 milliseconds to inject fuel for a single combustion event (would be 100% duty cycle at that RPM).

[nwdean]

I usually like to have injector data plotted out to at least 40 milliseconds, as that would be 100% duty cycle at 3000 RPM (unlikely to require that kind of range at such a low RPM in most setups, but not impossible with low revving, mid-range power setups).

At 6000 RPM, you only have a window of 20 milliseconds to inject fuel for a single combustion event (would be 100% duty cycle at that RPM).

I am probably going to have to read some more on that to understand exactly what you mean. But just throwing this out there. The picture below is the table from the RIPP supplied tune and the last cell was removed from the one I was given by the person I paid to tune this. Does that relate to anything you mentioned? Always thought it was weird because it was unlike anything else in the table but had no idea what it meant.
last cell of injector table.png

[B00STJUNKY]

I am probably going to have to read some more on that to understand exactly what you mean. But just throwing this out there. The picture below is the table from the RIPP supplied tune and the last cell was removed from the one I was given by the person I paid to tune this. Does that relate to anything you mentioned? Always thought it was weird because it was unlike anything else in the table but had no idea what it meant.
last cell of injector table.png

Yes, that table, and its inverse. I quickly checked the part number on the injectors you mentioned that are installed in your car, and there weren't any immediate hits for good data on them. At a minimum, I like to make sure there is at least good injector PW vs voltage offset data, since there are reasonable and simple enough ways to reverse engineer the mass vs PW portion of the injector data.

[nwdean]

Yes, that table, and its inverse. I quickly checked the part number on the injectors you mentioned that are installed in your car, and there weren't any immediate hits for good data on them. At a minimum, I like to make sure there is at least good injector PW vs voltage offset data, since there are reasonable and simple enough ways to reverse engineer the mass vs PW portion of the injector data.

I'm actually thinking it was your post I saw all of the calculations on regarding injectors and getting the table right. I can't find the link I saved at the moment, but was that you?

[B00STJUNKY]

I'm actually thinking it was your post I saw all of the calculations on regarding injectors and getting the table right. I can't find the link I saved at the moment, but was that you?

Very possible. I have a lot of posts on this site, so it's hard to pick out exactly which post you might be referring to.

[GHuggins]

It was possibly Jay's on how to tune the ann system. That was actually something else I noticed in your tune. Don't recall 100%, but I don't believe your inverse tables were ever changed to match the main fueling table. Going off of memory on that one as I don't have a way to verify right now.

[nwdean]

It was possibly Jay's on how to tune the ann system. That was actually something else I noticed in your tune. Don't recall 100%, but I don't believe your inverse tables were ever changed to match the main fueling table. Going off of memory on that one as I don't have a way to verify right now.

I am actually not sure what you mean by that? Whenever you get a chance could you clarify a bit?

Also, Happy New Years Eve everyone!

[GHuggins]

Must have been someone else's I was looking at - just double checked yours and it is correct. Basically the tables and axis for the injector pulses should be inverse of one another.