Lean transition into PE and lean spot during WOT

[schpenxel]

lol, different error this time..

"Remote tuning error, unable to open this file. this file is part of a remote tuning network that you are not part of"

[WS6HUMMER]

lol, different error this time..

Remote tuning had the lock ID, cleared it. It didn't have a lock ID earlier when you told me to clear the master/slave. It's gone now,crossing my fingers again OLMAF WITH NO PREDICTION COEFF.hpt

[schpenxel]

It opens! lol

[WS6HUMMER]

It opens! lol

Thank goodness! I hope I just did something wrong but I got a feeling you're gonna say otherwise.

[WS6HUMMER]

Made a few pulls on my dyno, engine builder and owner was there. I calmed down the delay quite a bit actually & we made 11 more hp than the cam claimed with 5 hours on the dyno. I hate E38's!

[Rawr256]

Bumpity bump!

Just curious if anyone tracked this down? Recently threw in new injectors in my LSA G8 setup and get the same thing, approx 2.1 seconds into PE get a lean blip of about a point and half or so. Noticed with less throttle when in PE it is a more severe lean spike. Recently just did the double stoich half IFR stuff to make all my other stuff report correctly and used the info from the manufacturer for the injectors. I know I didn't have the issue with the stock LSA injectors and if WOT long enough to get gear changes the lean spike never comes back after the initial hit so leads me to believe it is something being overlooked possibly related to time? Have watched fuel pressure on the dyno during a pull and it doesn't seem to have any issue maintaining pressure during the run so kind of have fuel delivery ruled out.

Since I'm running the SD2 OS I was thinking about doing the boost activated PE to see if it made a difference with it. Thinking about it this morning while driving into work I remember my buddies CTS-V doing the same thing that always had us scratching our heads thinking it must be pump scavenging when launching maybe going down the track. Now thinking it is most likely the same thing.

[Niemer]

I think the injectors are actually shutting off for a fraction of a second. I don't have an oscilloscope to verify, but that's about the last thing that makes any sort of sense to me.

[GHuggins]

This is probably a long shot, but are the people having this problem messing with transient fueling tables or still running the prediction coefficients? Only reason I ask is because I've noticed that transient fueling actually last about 2 to 3 seconds or roughly a 1000 to 1500 rpm span. If not dialed in correctly for instance, it can cause you to falsely pull fuel or add fuel in areas where you shouldn't be. So I was just wondering if the prediction coefficients or transient fueling in general was where the problem was originating?

[Niemer]

I've messed with the transients and have prediction coefficients 0ed out.

[GHuggins]

What does it do with stock transients? When you say you've messed with them - how exactly?

[Niemer]

Stock or modified transients don't affect this. Admittedly, I don't know much about what exactly these tables do other than it's similar to what a pump jet does on a carb, but I've tweaked just about everything with no change to this phenomenon.

[Rawr256]

I played with transients when using the stock LSA injectors to get rid of a lag with fueling when going into PE so my settings are off from my stock values. I've played with them up and down to try and eliminate it also with no change.

One thing that I did notice is when I have the entire MAF curve increased to a point where my actual drops well below my commanded, the spike still happens with the flow of the curve at the same time. It's almost like there is another table that is momentarily being referenced telling the injectors to pull back and then go back. Similar to the richest AFR being used with some ECMs between the OL and PE. Are you using a SD2 OS Niemer?

[GHuggins]

Do you mind posting a log with the issue present and point out where exactly to look. Also if it's OK or you don't mind - current tune and an OE tune for comparison? Log as many things as possible including injector temp, PE commanded, Air fuel or lambda commanded - actual air fuel or lambda - which ever you use and all torque management pids too please... I haven't experienced this ever that I know of, so just curious...

[07GTS]

if your "fuel from wall stabilization" is set to 1 try changing it to 2 and see if that helps, saw GHuggins mention it in a post about it maby affecting the different spray patterns of injectors so if u have gone from LSA injectors that spray onto the valve (value of 1) and now u have different injectors it might be worth trying it on 2 so its expecting more to be on the walls so it will compensate..?

[Niemer]

Files attached, don't mind the knock, that's been fixed. It's not my latest tune, but the latest that shows a good example of what we're talking about.

[Tre-Cool]

Not sure if there was ever a solution or cause that someone found for this, but i have a car that can do wierd stuff for fuelling and a noticable jerk when doing power runs on the dyno. with the injector signal plugged into the dyno there is a momentary injection duration increase along with a injector pulse drop logged by the dyno. while the logger doesnt show it. (im using efi and hpt)

now i managed to fix it during testing by disabling PE. the car runs open loop all the time anyway so i just use the open loop map table to enrichen. i can do back to back dyno pulls, flipping pe on and off and the results are the same everytime.

with PE on, i get stumble and lean out. pe off and no problems.

I can post screen shots from dyno and logger if you want more details. this car is an 07 ve commodore, with a 403ci motor with 100lb injectors.max duty cycle is 43% on pump but it's setup for flex fuel.

[Niemer]

Awesome that there is actual data to back this up now! Please share! I think someone else in this thread came to that same conclusion, but on the street without the additional logger and data to back it up. Now if someone has the smarts to help the HPTuners team identify if there is a hidden table or switch in the software based on this info...

[10_SS]

Tre-Cool if your still interested would you mind posting a log or pics of the dyno showing this? Maybe then someone who has this problem could get a PW to Analog 1-5v converter (if fast enough) and wire to an injector, and pipe that signal into one of the HPT Analog Input channels... see if you can catch it that way. I don't have this problem for some reason but am interested why so many people do. Little more data maybe it is something HPT could look into. Just wonder if it's some kinda Transient setting, since I DO NOT get a measurable transient above 4000rpm from the HPT reported Pulse Width, proven on a bench many times, but others say their fueling shows there is a transient occurring.

Also, someone having this problem could wire an injector to a Laptop Mic input, and run something like Sound Card SCOPE... https://www.zeitnitz.eu/scope_en I use it for many things... awesome little program using your sound card mic input.

[cc-rider]

Not sure if there was ever a solution or cause that someone found for this, but i have a car that can do wierd stuff for fuelling and a noticable jerk when doing power runs on the dyno. with the injector signal plugged into the dyno there is a momentary injection duration increase along with a injector pulse drop logged by the dyno. while the logger doesnt show it. (im using efi and hpt)

now i managed to fix it during testing by disabling PE. the car runs open loop all the time anyway so i just use the open loop map table to enrichen. i can do back to back dyno pulls, flipping pe on and off and the results are the same everytime.

with PE on, i get stumble and lean out. pe off and no problems.

I can post screen shots from dyno and logger if you want more details. this car is an 07 ve commodore, with a 403ci motor with 100lb injectors.max duty cycle is 43% on pump but it's setup for flex fuel.

I also have had really really good results using the open loop map/rpm table for fueling. I'm not sure why this table is not used more by those of us who modify for higher HP. You can have it gradually enrich as it goes into higher map or boost...or higher rpm. Or you can have it be an on/off switch just like PE does.

[Tre-Cool]

I also have had really really good results using the open loop map/rpm table for fueling. I'm not sure why this table is not used more by those of us who modify for higher HP. You can have it gradually enrich as it goes into higher map or boost...or higher rpm. Or you can have it be an on/off switch just like PE does.

Absolutely. I've been using it for years. I setup the pe enrichment table to something like .87 lambda, but then use the open loop tables to run up to 1.25 EQ for the higher map/boost ranges.

HOWEVER, this only works if the car is permanently in open loop. the second you enable closed loop again the tune ignores the table entirely.