Help figure this lean spike out on my Sonic

[Flyer]

2012 Sonic turbo M6 - bone stock, cept for the tires.

See the files attached for what's been done to the tune. In the log file, if you notice at ~4800 the injector duty cycle starts going down. It eventually causes knock unsurprisingly as it leans itself out. It soon corrects and straightens out.

I can't see to find what causes this to happen. I can tell you the stock file doesn't do it, but I don't see where I've made any drastic changes in the current tune.

It pulls very nice, up to where it has that hiccup. It's a very noticeable stumble and then it tries to start pulling again, but not ever as good as it was before the hiccup.

At frame 825, that's 2nd gear of a 2nd and 3rd pull.

[Spawne32]

Who made these changes to the tune first of all, I see a lot of odd changes done to fueling.

[Cruze]

I think it is your PE table. Just because it commands 13 AFR in the midrange does not mean that is what the engine is actually seeing. I run about the same airflow and run stock PE enrich table with stock timing.

[Flyer]

Spawne, I did. Define odd, lets work through the logic and see how odd my thinking is. Which ones are you referring to.

Cruze, I thought that too, but it doesn't make since to me. I thought maybe it's a glitch since it's happening right there where it starts to richen up. I added the .001 to the 2.500 in an effort to clear a glitch, but no dice. Following the PE table, it should start out and richen itself up.

I changed the PE table because at heavy throttle, I'd see really lean conditions down low (1.066) and it would start adding fuel and clear up the knock and run better.

[Flyer]

I just re-read this ... it should say I added the '.001 to the 1.250 in the PE table in an effort ...'

[Spawne32]

Spawne, I did. Define odd, lets work through the logic and see how odd my thinking is. Which ones are you referring to.

Cruze, I thought that too, but it doesn't make since to me. I thought maybe it's a glitch since it's happening right there where it starts to richen up. I added the .001 to the 2.500 in an effort to clear a glitch, but no dice. Following the PE table, it should start out and richen itself up.

I changed the PE table because at heavy throttle, I'd see really lean conditions down low (1.066) and it would start adding fuel and clear up the knock and run better.

Well let me start with a few questions first off, try to get an understanding of what you did.

Under Deceleration Fuel Cutoff, you lowered the fuel cutoff to 1200rpm, why not keep it stock?
Under PE throttle/pedal I see you lowered the require pedal position for PE to enable, that is fine.
You raised knock enrichment to 275 thus disabling it, this is not something I would do on a turbo car. If you are having knock, deal with the knock, otherwise don't change this, this could potentially save your motor should it run lean and start pinging.

Your PE enrichment table is bonkers compared to what im seeing as stock from the tune file i pulled from the repository, im going to post a picture of the stock PE table, but curious as to why you made any changes at all to this on a bone stock car.

I would raise your enrichment ramp in to 1, doesnt need to be as slow as .5. Since you seem to want PE to enable faster.

Your car delays PE to a very high RPM stock, im not sure the reason for this entirely but if it wants it that high stock, I would not immediately go from 6000rpm to 1rpm when adjusting the PE delay table. Work your way backwards and tune PE slowly and work your way backward to around 800rpm, it doesnt need to be enabled below idle.

Disabled Cat Over Temp Protection.

adding 3 and 4 degrees to the entire timing table is not the way to raise timing, I would return that back to stock, you only need to raise timing in the areas that the car will actually see and then smooth out from there. Spark tables are artwork, highlighting the whole table and just adding timing can cause disastrous results if you dont know what your doing. I typically save that for a dyno or track and only raise a degree at a time while watching for KR and watching out the fueling changes.

Take your high octane table and copy it directly over to the low octane table, this keeps both your spark tables the same, so that if the car detects a string of knock, and it switches to the low octane table, the spark doesnt change leading you to believe that your high octane table is knock free. Once you tune a knock free high octane table by having them both with the same settings, you can switch the low octane table back should you ever encounter bad gas or something.

Never increase your knock retard decay rate table more than 10%.

[Spawne32]

stock table up top, your table on the bottom, why such drastic changes?

[Flyer]

Well let me start with a few questions first off, try to get an understanding of what you did.

Under Deceleration Fuel Cutoff, you lowered the fuel cutoff to 1200rpm, why not keep it stock?

Doesn't hurt anything and if it'll keep it in DCFO longer, that means less fuel used.



Under PE throttle/pedal I see you lowered the require pedal position for PE to enable, that is fine.

This way it hits PE mode under boost sooner. I had a previous vehicle that I put a charger on, the tune that came with it had it going into PE mode at 60%, it started seeing boost around 55%.



You raised knock enrichment to 275 thus disabling it, this is not something I would do on a turbo car. If you are having knock, deal with the knock, otherwise don't change this, this could potentially save your motor should it run lean and start pinging.

Troubleshooting the lean spike, trying to see how much and why the computer is over correcting itself. Turns out, this was HUGELY over correcting, somewhere in the range of 10.5 or so AFR. It still spikes once the Inj DC picks up, but not near as bad. THe knock is coming from the lean spike.



Your PE enrichment table is bonkers compared to what im seeing as stock from the tune file i pulled from the repository, im going to post a picture of the stock PE table, but curious as to why you made any changes at all to this on a bone stock car.

The PE table in stock form had the car going 13.6 up to about 4500-5k, not good on a turbo car, not good for making power. The difference is very noticable. More on that later.



I would raise your enrichment ramp in to 1, doesnt need to be as slow as .5. Since you seem to want PE to enable faster.

Personal Preference, it's in full PE by the time it hits boost, and the PE table is smooth enough it's not gonna need anymore rate than that.



Your car delays PE to a very high RPM stock, im not sure the reason for this entirely but if it wants it that high stock, I would not immediately go from 6000rpm to 1rpm when adjusting the PE delay table. Work your way backwards and tune PE slowly and work your way backward to around 800rpm, it doesnt need to be enabled below idle.

I didn't want delay, so I adjusted all delay parameters to an unreachable parameter. Doesn't matter if it's 2k or 1, as long as it's not below that when PE enable, it won't be delayed. No delay was the goal and that was achieved.



Disabled Cat Over Temp Protection.

No it's not.



adding 3 and 4 degrees to the entire timing table is not the way to raise timing, I would return that back to stock, you only need to raise timing in the areas that the car will actually see and then smooth out from there. Spark tables are artwork, highlighting the whole table and just adding timing can cause disastrous results if you dont know what your doing. I typically save that for a dyno or track and only raise a degree at a time while watching for KR and watching out the fueling changes.

Only KR I get is from the lean spike, it was highlight the whole table. I can post a screenshot of the compare to stock if you like. I very much agree with part of your statement, artwork yes, dyno no. No dyno will EVER reproduce real world driving conditions with the actual owner/operator driving the car on the streets in a real environment. Ever. No way. And if they did, I'm not gonna pay the fee to strap my car to it and spend the time and miles I have driving on the street to get the tables nailed down when I can do that while driving the car.



Take your high octane table and copy it directly over to the low octane table, this keeps both your spark tables the same, so that if the car detects a string of knock, and it switches to the low octane table, the spark doesnt change leading you to believe that your high octane table is knock free. Once you tune a knock free high octane table by having them both with the same settings, you can switch the low octane table back should you ever encounter bad gas or something.

My wife also drives the car and fuels it up, while she's in the habit of putting supreme in, it's nice to have a fudge factor. It's also nice to have that factor for when the fuel stations seem to manage to put regular in the supreme tanks. (Happened before with my old truck. Something about 11.5:1 compression and tuning on 93 octane, it wasn't happy. Sounded like marbles running through the intake.)



Never increase your knock retard decay rate table more than 10%.

Again, personal preference. Helps spot false knock. Habits from the old days. If it goes and stays away, more than likely false, if it goes and comes right back, its for real!




Maybe you will see that not all tuners are the same. While there are some principles to follow. There are different schools of thought. Hopefully instead of being insulting and thrashing one's thought process for being wrong, when it's only different; we can discuss this as a community and learn from each other. More on the PE table and my attempts from last night coming.

[Flyer]

OK, PE table .. Please see the clips below.

In the stock AFR pic, notice how high the AFR is in PE mode. Bad for performance. Bad for the motor, creates to much heat, etc, hopefully we all know what a high AFR under WOT does.

In the 'my AFR', notice how much flatter it is? You can tell a very noticable difference in performance. It pulls very nicely down low.

Finer tuning is NEEDED, but I'll wait until I at the very least get a new down pipe with a bung for my wideband IN FRONT of a catalytic converter. Only way to do it right, and why I won't be pulling fuel until then.

With adding that fuel down low, it should let me add some timing too. Before I do that though, I need this lean spike moved out.


Last night, I adjusted the PE table where the change in AFR is a bit sooner, with no luck. The lean spike did come in sooner, but it's still there. I then tried putting it back to stock, still there. I put the driver demand table back to stock, still there. I'll find it eventually, but I was hoping not to have to start over or have to go through tables one by one. But I can tell you it's not there with the stock tune.

[Flyer]

Does anyone know more specifically about this table?

EQ Torque Ratio.JPG

[cobaltssoverbooster]

its a fuel combustion efficiency table. setting it up correctly tells the ecu what each fuel EQ Ratio makes for torque at each rpm value.
they use 1.0 Fuel EQR as a base and adjusted it richer and leaner to see what kind of trq is produced. if trq increased then the ration listed would be positive.
this table is hard to adjust without some form of verifying trq output through either a dyno or accurate estimation software like virtual dyno. most people leave this alone until a massive change is made like boost source swap or nitrous application which changes fueling drastically compared to factory application.

in the lnf its a 2d graph called lambda efficiency. (screenshot attached)

[Flyer]

Found the culprit ... Engine > TM > Turbo > Pressure Delta Max

I feel better now. I started back from stock and started on tab at a time copying from the work I already had. I skipped that table because I didn't see it as a real performance, just something to let it build boost faster. All was good. I went back and changed it before changing the PE table. The lean spike came through. Changed the Pressure Delta back to stock and put the PE table back to where it was after I changed it up and still good to go.

Up to about 4500 it really sets you back in the seat. It's kind of impressive really for what it is.

Now, something I'm seeing is the boost will fade off as the rpm's raise. I don't see where that's coming from, but you can certainly feel it.

[Spawne32]

Found the culprit ... Engine > TM > Turbo > Pressure Delta Max

I feel better now. I started back from stock and started on tab at a time copying from the work I already had. I skipped that table because I didn't see it as a real performance, just something to let it build boost faster. All was good. I went back and changed it before changing the PE table. The lean spike came through. Changed the Pressure Delta back to stock and put the PE table back to where it was after I changed it up and still good to go.

Up to about 4500 it really sets you back in the seat. It's kind of impressive really for what it is.

Now, something I'm seeing is the boost will fade off as the rpm's raise. I don't see where that's coming from, but you can certainly feel it.

Turbo is really small on that 1.4, so its not uncommon that boost fades off as the RPM's increase with small turbo car's.