PI controller pro's & Con's comparison: JB4 PI vs split 6

[Terry@BMS]

So a bit of an update, I'm single turbo now and was (unfortunately) forced to install a JB4 as it is currently the most reliable boost controller with some measure of integration for single turbo (idc what Motiv has to say about the boost box, in its current iteration I don't trust it).

I'm still using the AIC6 wired flash only, my fuel trims look much better than the logs from cars running JB4 integrated everything. I'm hitting 12.5 AFR target as written in the BEF with trims in the 15-35 neighborhood (STFT +/- 15%) vs. the logs I've seen from cars running the BMS controller where the fueling is way rich and trims pegged at 0 (-33% STFT).

There seems to be a general misconception on how to tune PI cars. Your fuel trims have nothing to do with PI tuning. PI has to be tuned so that high fuel pressure is being maintained at target, and then you need to level out the trims using either the fuel scalar tables in the flash or if you have a JB4 the open loop on the fly fuel trim adjustment. If you are tuning PI based on fuel trims, you're doing it wrong.

With our off the shelf stuff on single turbo, the suggested JB4 PI values of 80, off the shelf E85_PI BEF, open loop set to 0, trims are generally very level and fuel pressure is maintained. If they are not just shoot us a log for advice. If you're having to make major changes with our default settings then likely something is wrong. The JB4 already compensates for low pressure variations and other factors. Most common mistake resulting in negative fuel trims on PI with off the shelf maps is failing to reset the JB4 fuel trim control (open loop setting) to 0.

 

[Dreyo27]

Not added in yet, but very very soon. It also isn't just when there is a misfire, it is any time a cylinder's injector is cut for any reason at all, and there are a lot more reasons

If we get a custom tune from you and go MHD+AIC+flexfuel, can we have this feature?
Also is there any benifit do doing a FPR and a return line? (mmp1k+e85 with 700whp goal?)

 

[Abacus38]

If we get a custom tune from you and go MHD+AIC+flexfuel, can we have this feature?
Also is there any benifit do doing a FPR and a return line? (mmp1k+e85 with 700whp goal?)

The FPR and return line is generally needed at the power level because when the PI comes on it drops the fuel pressure

 

[veer90]

If we get a custom tune from you and go MHD+AIC+flexfuel, can we have this feature?
Also is there any benifit do doing a FPR and a return line? (mmp1k+e85 with 700whp goal?)

Also relieves pressure spikes on fast 1-2 shifts if you're manual with a twin 450 LPFP. Sudden reduction in fuel demand due to throttle closure but hobbs switch in the charge pipe is still signaling the second pump to run.

I have a 125 psi spike logged, lol

 

[laurean]

guys I do an inquiry I'm waiting for control pi I have armed independent fuel system I use a walbro 450 for the original pipe of the car and apart I have a stainless steel tank with a walbro 450 and a regulator in 50 psi regulator for the secondary ramp , is completely isolated from the original fuel system, do you think that could cause me some problem? I told them this was done in this way because I am in Argentina and it is very difficult to enter the fuel kits from outside and then it occurred to us to do this

]

[/ATTACH]

 

[cebrailbakan]

I’ve made my engine blown because of PI. Terry , my tuner didn’t tell me to set fuel bias to 20 , did also not to set FOL to zero , and run in map 1 to verify the things , and he didn’t make me remind that fuel bias settings are applied in all maps. So once I went to the high way to do a log and evaluate the things , I was in map 1 and fuel bias settings were set in 75 and FOL was in 40. The car took an immediate action and misfire cylinder 1 code popped up and never gone. Once we opened the engine , we saw that all cylinders walls were washed and crappy with scratches. Can’t you take any precautions for such situations , I think Jb4 should not let the fuel bias settings apply in all maps

 

[Terry@BMS]

Not in the loop on your tuning, sorry. But when racing sometimes engines break. It's just part of the game. Let's see what we can learn from it to prevent a future situation with better safety systems.

Fuel enrichment is scaled on boost, so even a setting of 100, on map1, is a relatively low amount of PI. Sounds like you had a situation of way too much fuel though. Would be the first time I've heard of engine damage from too much fuel but it can happen. We currently have a lean run safety active but not a "rich" run safety active. Maybe it's time to add one... Log of your failure?

 

[cebrailbakan]

I’ve had logs but it’s in my Android device at home, I will send it to you via email.

I’m running 750 cc Bosch injectors on the rail. Does your PI controller have the feature of adjusting the fuel amount ?
And what is the way to switching PI, on/off? I think it should be like meth , it should get active on only map3, map6 and map 7.

 

[Terry@BMS]

Just post CSV log here since it's a public discussion. Maybe others will have ideas on how to best implement safety for the situation I might miss.

We adjust fuel volume based on low fuel pressure, boost, engine speed, IAT, E85 mixture, and some other factors. I'm specifically interested though to see how AFR and fuel trims looked to see if we can use those as indicators that something is wrong. e.g. maybe we should failsafe if AFR is richer than 10.5:1 for more than a second.

 

[cebrailbakan]

Terry, the log attached when my engine has blown.

 

[cebrailbakan]

I was running ms109 race gas and a cm5 nozzle in the charge pipe for IAT suppression

 

[DCook]

@cebrailbakan what let go on your motor? Bend a rod, or multiples? Or do you know yet what let go/broke?

 

[cebrailbakan]

I stated above , unfortunately all cylinders had scratches

 

[DCook]

Just wondering how scratchs would cause it, unless it destroyed rings from being dry on the walls from fuel, and lost all compression.

 

[Terry@BMS]

Definitely rich.. Although, our F150 Raptor runs 10:1 at WOT all the time stock. So it's not obviously a cause of engine failure. Do you really think it was just an issue of too much fuel? Any outside opinion on whether we should set the JB4 to fail safe if AFR stays below say 10.4:1?

 

[Milan]

I don't think we should be implementing failsafes based on one member's misfortune. That whole story doesn't add up anyway. I've setup multiple ST cars on JB4 and PI and it was pretty straight forward if you follow all the directions and double check everything.

 

[Terry@BMS]

Always good to learn from mistakes and since engine failures are relatively rare, if we see something in one we can change, why not. The broader question is does anyone run richer than 10.5:1 AFR at full throttle? The only drawback with such a JB4 safety is "false alarm" if someone intends to run it that rich.

 

[dyezak]

Just post CSV log here since it's a public discussion. Maybe others will have ideas on how to best implement safety for the situation I might miss.

We adjust fuel volume based on low fuel pressure, boost, engine speed, IAT, E85 mixture, and some other factors. I'm specifically interested though to see how AFR and fuel trims looked to see if we can use those as indicators that something is wrong. e.g. maybe we should failsafe if AFR is richer than 10.5:1 for more than a second.

^^That's my favorite thing about Terry.

 

[cebrailbakan]

I don't think we should be implementing failsafes based on one member's misfortune. That whole story doesn't add up anyway. I've setup multiple ST cars on JB4 and PI and it was pretty straight forward if you follow all the directions and double check everything.

I don’t agree with you. It means now ‘ the one ‘ will may be the ‘ ones ‘ these days. Now that something new comes up, meaningly port controller , it should be innovated, of course.

Always good to learn from mistakes and since engine failures are relatively rare, if we see something in one we can change, why not. The broader question is does anyone run richer than 10.5:1 AFR at full throttle? The only drawback with such a JB4 safety is "false alarm" if someone intends to run it that rich.

I think there is much more than a drawback, and that is for people who always have to change fuel bias per map. I’d prefer the controller have
self-adjusted fuel bias for each map. For example , anyone can forget the fuel bias stuck at 80 in map 1 , like me

 

[Milan]

Always good to learn from mistakes and since engine failures are relatively rare, if we see something in one we can change, why not. The broader question is does anyone run richer than 10.5:1 AFR at full throttle? The only drawback with such a JB4 safety is "false alarm" if someone intends to run it that rich.

If you want to make things simple for people, why not offer default options? Wouldn't that be the least mistake-prone option if someone could click a button and default all the values to how it comes from the factory? Then you could have another one for single turbo, single turbo with PI option. IMO the biggest drawback about the JB4 is that the user interface/experience outside the steering wheel controls is counter intuitive. You should consider a design approach similar to what MHD chose where you just click on buttons.

Maybe work with the JB4 mobile guy to implement a wizard since it's a paid program, would be a great value add IMO.