EFIDynoTuning Forum

Tried messing with this in open loop - So I found that the LAMBSE is commanded based on the calculated PERLOAD. I appear to be hitting a pretty high load when stabbing the throttle (in some cases 70 LOAD between 1000 and 1500 RPM) which is causing it to calculate a richer LAMBSE based on fuel table FN1362 and FN035.

I can mess with values if I want I guess to get that under control, and I did to some extent - what I found that I thought was weird was that when I changed things around to have a LAMBSE closer to 1.0 when stabbing the throttle (instead of .88 before), the amount it went lean afterwards also went down. So less fuel went in when stabbing it, but also the amount it went lean afterwards came down too, by about 2 AFR points.

Is there some voodoo going on in the background with transient functions looking at HEGOs even in open loop that see "hey it didn't go that rich, so we don't need to pull as much fuel" - that's the behavior I'm seeing anyways.

Thanks - do transients end up as part of the calculation for LAMBSE, or is the transient value something calculated and used in the background?

I have a tip-in/out issue I'm trying to figure out if its transients or something else. Right now on a sharp tip-in/out (like quick rev) I can see the LAMBSE go way low, AFR goes rich, then it goes way lean even though LAMBSE is not commanded lean, in fact it stays < 1 until AFR stabilizes.

Does anyone know which transient fuel functions/scalars are supposed to be scaled when scaling the tune for larger injectors? I have a feeling I'm missing one of these.

I got lockup to respond at factory points using the duty cycle table:

FNDCNOCAP - Converter Clutch Dutycycle for No Capacity. Boosting these values higher got it to lock hard, maybe a bit too hard.

There's another similar table that I couldnt figure out what it was affecting as it didnt seem to respond to changes

FNDCNOSLIP - Converter Clutch Dutycycle for No Slip

I started with changing that one figuring the description made more sense to change, but it didnt do anything.

Anyways looks like I'll be messing with these and other settings to get it right.

Thanks I'll take a look - to confirm my strategy has these

SR_HL - Converter Clutch Hardlock Speed Ratio Min - right now this is at .80, I should try a lower val?

I also have SRLUMN which is labeled "Speed Ratio Max to Unlock Torque Convertor" stock value is .650

OK now I am stumped as to where my issue may be. I thought I was having a converter issue but now I think it may be something else. I was fighting a sluggish lockup in 2nd with the old converter, and what I felt was too loose of a converter in general.

I've completed my converter swap with new triple disc lockup converter. The car drives great, shifts normally, power seems to be put to the ground now. Now I'm fighting no lock-up issues, particularly in 2nd gear. At some time this car would shift into 2nd and lockup right away.

I've data logged BCSDC for a quick drive and I'm noticing it staying mostly at 0 in 2nd gear, occasionally I can see it climb into 30-40% and feel it start to lock but then it goes back to 0 and it doesn't seem there's rhyme or reason to why duty cycle goes up or back to 0.

In 3rd gear, duty cycle goes to 100% and I can feel it hard lock.

Based on the tune I can't see the reasoning for this, 2nd Gear lock schedule looks like attached (I've left these functions stock), Slip tables for 2 and 3 I've zero'd out.
I hope I'm not trying to track down a nightmare electric issue. BCSDC a commanded value by the EEC am I correct? Trying to figure why its not commanding expected values.

Thank you - yea I currently have a single disc lockup converter, once I have the triple disc in I will be locking it up more.

After converter stall, I assume an efficient converter should approach 5-8% slip even when unlocked, just by virtue of the fluid coupling. This is well beyond the stall RPM and still seeing about 20% slip. Hoping the new converter built to my specs cures this.

I have a 4R70W swap with a Precision Industries 3200 stall (honestly not spec'd to my current power level) that I run unlocked. I suspect my converter is either too loose, inefficient, or my transmission is slipping. I've felt a somewhat steady decline in acceleration performance each time I take my car out - some of this can be attributed to hotter weather or me getting used to my car's power level.

I don't think its an issue with the motor - I gauge this by the data logged amount of air this sucks in via the MAF and commanded Fuel / AFRs being pretty consistent with all other factors fairly equal. I figure if its making less and less power these values would also go down.

I've started by looking at data logs of MPH vs RPM. With these values I've calculated somewhere in the neighborhood of 15-20% driveline slip approaching the top of 2nd gear, and when it shifts into 3rd, there's a calculated 34% driveline slip. This was calculated using TCI's converter slip calculator. I don't know if this is the most accurate way of calculating slip just because of a potential delay between logged RPM and MPH values.

I found PID's for Output Shaft RPM (NOBART) and Speed Ratio Across Torque Converter (SPD_RATIO). I started logging these now but didn't get a good run in, I reached about 5400RPM in 2nd where it showed a value of 0.81 for SPD_RATIO. Does this mean 19% converter slip? Or is the way this is calculated make it a potential transmission slip as well?

Curious if these methods are fairly accurate to measure driveline slip, if so seems I need to investigate my transmission/converter. I already have a new triple disk converter on order so I can lock it up reliably, I'm hoping there's less concern on the trans.

Thanks!

Thanks I will take another look at idle air to see where I might have gone wrong.

I was going thru an idle behavior issue with the U4P2 tune where it would sit at feedback min clip (SPK_FBS_MIN set at 10 in the U4P2 tune).

With the U4P2 tune, the combination of spark values never allowed for the EEC to play with timing to stabilize idle.

Feedback Spark Desired Torque (SPK_LOAD_RES) in U4P2 was changed from the stock .05 to 1.35. The U4P2 value when looked up against Spark MBT Retard for Torque Limiting (FN799) always came up with 0 which didn't allow any Feedback Spark Gain when RPMs dipped below the set Idle values. I changed this back to stock.

What this led to was (keep in mind I have a non-stock turbo cam) idle sometimes dipping below the set RPM values and then a sudden surge as the EEC added timing to stabilize it. This was different from stock behavior where it appears to constantly modulate timing, ISC and Fuel to keep it steady. Honestly, the stock method held a much steadier idle, and sounded healthier so I investigated which values I had to change to make it behave like that.

Spark MBT table (FN2300) was scaled with a minimum of 1250 RPM and 30 load, which was beyond the stock min values where my idle RPMs and load sit. I changed these scalers back to stock minimums while leaving the higher load scale values and filled in accordingly. I had to change the other impacted tables by the scaler values as well.

I changed SPK_FBS_MIN to 20. This clipped timing at a minimum of 20* at idle.

The result was a much healthier sounding and less fluctuating idle which eliminated the sudden timing surges to stabilize to idle RPM settings. Instead of sitting at min clip, the timing is constantly modulating between 20 and 25 degrees along with minor ISC and fuel changes. The idle deviates much less from rpm values than before.

@decipha I'm curious to know was there something I'm misunderstanding with the U4P2 values in the downloadable tune or was there additional theory around getting a stable idle while timing sat at min clip and only allowing ISC and fuel to stabilize RPM? To me having timing aid in the stabilization makes it run much smoother.