Leaning out high RPM

[3400-95-Modified]

I just decided to stop messing with the PE AFR table long ago. While I guess it could modify the delivered IPW in PE mode, the idea of telling a narrow band system to run a specific AFR seemed pointless. In the OP's case his VE tables add up to like 110 in some spots so there is no way that it would make any difference.

I once thought the same thing, but the narrowband isn't used to report that A/F to the ECU and make any adjustments at WOT, hence why you need to use a wideband to properly scale your other tables that produce this result. This is why I spent a lot of time on my tune and matching my commanded a/f ratio to the actual wide band reading. I did that by making multiple pulls logging the wide band with the ecu and then comparing the commanded and wb readings and then tweaking the maf table to either bring it up or drop it down. Remember the ECU has really no idea what the actual A/F is but its using the scaled tables you created to get that a/f ratio, so its output is only as good as what you've set it up to use. This is very similar to how I tune part throttle but this you can and typically use the fuel trim system to get those tables properly scaled... Its the same principal as WOT except the ECU is providing you with the adjustment value its using to get to the commanded 14.7 a/f that is set in the closed loop commanded a/f table.

Glad to hear the fpr was an easy fix or at least temporary fix for now... and good to know you found the issue and it wasn't something larger.

[LZeppelin513]

anyways, OP.. good luck with your tuning!

Glad to hear the fpr was an easy fix or at least temporary fix for now... and good to know you found the issue and it wasn't something larger.

Thanks, I couldn't be able to any of this without the information from helpful forum members like you guys!

Big thanks to everyone who has been helping me with all my tuning questions lately.

[Superdave]

Sounds like the normal tuning process to me.. lol

been there, done that and sold 100+ swap chips based on countless hours of road and dyno tuning.

[3400-95-Modified]

Sounds like the normal tuning process to me.. lol

been there, done that and sold 100+ swap chips based on countless hours of road and dyno tuning.

Everyone has their own way of doing it and I'm sure that each way get's the job done, but once I'm done with what you call the "normal tuning process" I would use the PE modifer vs AFR vs RPM table to add in more fuel in the future, where as back in the day DHP users said to just change the MAF scale to do that. I'm not trying to belittle anyone's "process" here I'm simply stating that if you do use the said table above it will adjust the a/f ratio if the rest of your static table are scaled properly.

[robertisaar]

as stated, it's not closed loop when in PE. you could get a solid AFR by tweaking VE at higher loads, but then closed loop fueling is effected as well should you hit those cells in closed loop.

and the factory tables look beyond stupid for most calibrations. this being BFBD (91-92 W-body LH0/4T60):

[Superdave]

Robert, what's the math look like for that? (if you don't mind). I'm curious how the code offsets the total VE from the tables VS the value you type in the commanded AFR table.





3400-95-Modified, I wasn't saying anything bad, just agreeing that your process sounds just like what i've always done. it is the most logical way. I just chose to dial in the AFR's with the base VE table and leave the commanded as a reference. I do the same with idle fuel, cold start open loop, lean cruse mode etc...

[robertisaar]

PE AFR table has lookup done, has high MPH/high coolant/high PE time check done and if necessary accounted for (PE AFR richened for those conditions).

then PE AFR and current target AFR are checked against to see which is richer, that value is used. cat overtemp AFR is checked if necessary, richer of the two AFRs is kept and used. then mode 4 AFR is checked to see if commanded, if so, it's used regardless.

that's how the target AFR is determined, leaving out all of the closed loop/choke/cold open loop stuff.

then when the code gets around to calculating a new BPW:

target AFR turned into a 16 and then 14 bit value, divided with 8-bit "airflow"(byte F2) and stored as the "fuel required" double byte (word 8B).

VE correction (byte 8A) then takes place with 8X16 multiply and stored to "fuel required"

MAP correction (byte 56) then takes place with 8X16 multiply and stored to "fuel required"

BPC vs Intake Runner Temp (byte A2) then takes place with 8X16 multiply and stored to "fuel required"

that ends the speed-density calc. after that, BLM and INT correction take place.



i'm really not a fan of all of the 8 bit values getting multiplied, too lossy for me.

[Superdave]

yah, a little weird but i guess it works. I'll edit my " PE commanded AFR table does nothing useful at all. Ignore it." statement and just put my opinion on it instead.


No need to post it up but i'm curious how intake runner temp is calculated. I'll dig through that sheet you sent when i get some free time.

[robertisaar]

i believe i posted it in another of LZeppelin513's threads, but i don't remember which now.

[LZeppelin513]

No need to post it up but i'm curious how intake runner temp is calculated. I'll dig through that sheet you sent when i get some free time.

http://60degreev6.com/forum/showthread.php/50563-Does-the-BLM-vary-with-engine-temp/page3