What AFR?

[sprucegagt]

For maximum HP then your right, Dyno is the only way to go. But your cruise tune has to be right before you can get a reliable dyno at WOT.

As for the tune to 7500 Hz for cruise then PE beyond that, well I think that's just bad advice. It didn't work for your car so why would it work for anyone else? If you were new to tuning you would think this is right yet would probably have KR starting somewhere in the 4000 - 7500 Hz range and you wouldn't know how to fix it other than lowering timing.

[MMGT1]

Dyno is the only true way to go, but I can't afford any more trips there. This way I know I am safe, that's why I selected the 12.9 rather than have PE start at 13.2 and then go down to 12.xx. The most power I saw with my mods was at 12.9 actual on the dyno. That's why I went with 12.9 for all values. If I could get a couple more hours with the dyno I could do a lot more now than I could do then. And like you said about the cross over, I didn't like the 7500 mark too much myself, but that is what "they" are using. Truth be told, with my tune I used 7000hz as the crossover, not the 7500 as they suggest. But I have heads, TB, cam,bla bla bla, and I thought that was the reason I went into PE so quickly...

[sprucegagt]

Appearently the VE table is %, not actual VE, is that what you mean? When tuning this way(what I've written above) this will allow you to command the 14.7 for the entire MAF signal. Only tune up to 7500hz with this. Then you command your PE mode(12.9 for me for the entire scale) and only tune from 7500hz and up.
Then when you plug the stocker back in the O2's stay very close(if you did it right) and WOT is bang on.
But again, with DHP there are tables that I don't have acess to with HPT(V6's). If this was an LS1 then it would be totally different.

But the PCM is commanding 14.7 AFR during closed loop operation so why worry about it in open loop unless your in PE?

I'm noticing a difference in philosophies (I know I spelled it wrong) between the two tuner camps on how to actually tune your car. HP is all about getting certain AFR numbers at specific times. DHP is about getting tables tuned to your particular vehicle needs, instead of just looking for certain AFR values at all times. AFR may be more or less than 13.0 at WOT, it just depends on what your vehicle needs. Makes you wonder which method is better?

Now I've seen plenty of cases in my car where PE activates well before 7500 Hz. If I tuned my car using your method then I would be lean until I hit 7500 Hz. That doesn't sound right to me.

You are correct about the VE table. Didn't know if you knew that or not.

[MMGT1]

Appearently the VE table is %, not actual VE, is that what you mean? When tuning this way(what I've written above) this will allow you to command the 14.7 for the entire MAF signal. Only tune up to 7500hz with this. Then you command your PE mode(12.9 for me for the entire scale) and only tune from 7500hz and up.
Then when you plug the stocker back in the O2's stay very close(if you did it right) and WOT is bang on.
But again, with DHP there are tables that I don't have acess to with HPT(V6's). If this was an LS1 then it would be totally different.

[sprucegagt]

Hey Spruce,
Car is open loop as soon as you unplug the "factory O2" for tuning purposes only. All in the write up.

The lean spike is because of the crossover between 4000hz to 7000hz actually. When you have tuned the high end and the low end, then pluging the "factory O2" back in there will be no error in fueling. Both stoich and PE are good! Again, in the write up....

Using PE, then commanding the 14.7 is the key to it. This way when tuning you don't have to weld a bung into the exhaust. For your personal use you can put in the bung and tune all you want in any way you want. This makes it very simple and I have all of my stoich values ranging from 14.5 to 14.9 on the WB. Then at wot I'm a steady 12.9. Now this will change slightly from day to day because air charges change with baro pressure. You can tune every day if you want to, you'll never be 100%, 100% of the time.
What this does is make it quick, accurate and out the door for the next one
The only reason you don't need ve is because you run a MAF. Your car will only reference it if there are HUGE differences between the VE table and your MAF. VE tuning is good if you want to put the time into it, but leave it till the end. There is a lot more to do first. Now, you can set up your tuner to show error % in ve as well, so it could be done very easily. Point is, when the MAF eails on our 3400's the car will go SD! I would not drive 5 miles in SD, my 2 cnts.
I know you will have lots to say about this but have at her bud, I am always willing "TO LEARN"...hahahhaha

You misunderstood my question. During normal operation (i.e. with stock O2 plugged in) the car is in closed loop operation about 98% of the time. The only times it's not is at startup and PE. So I'm wondering why are you worried about getting the open loop AFR right at cruise when it won't be in open loop? Are you trying to get the actual AFR dead on 14.7 all the time with no signal sweep? The O2 and PCM are not designed to stay dead on 14.7 with no signal sweep, so I don't understand why your doing this?

Now the lean spike. What are you calling a lean spike? Staying at a commanded 14.7 AFR while at WOT or having an enrichened AFR but the wide band is showing a lean spike?

During PE, you keep a steady 12.9 AFR all the time? Why not lower it gradually when the engine heats up?

Your wrong about the VE table. The MAF is a multiplier on the VE table. I've seen scans proving this and other people on the DHP forums have verified this. Yes SD mode does cause the transmission to go into fail safe mode, meaning full line pressure shifts. It's not damaging unless you leave it like this for over a month (don't ask how I know this lol). But for short distances, liking getting to a nearby repair station, then it will work. Also did you know the VE table is not a true VE table?

[MMGT1]

Hey Spruce,
Car is open loop as soon as you unplug the "factory O2" for tuning purposes only. All in the write up.

The lean spike is because of the crossover between 4000hz to 7000hz actually. When you have tuned the high end and the low end, then pluging the "factory O2" back in there will be no error in fueling. Both stoich and PE are good! Again, in the write up....

Using PE, then commanding the 14.7 is the key to it. This way when tuning you don't have to weld a bung into the exhaust. For your personal use you can put in the bung and tune all you want in any way you want. This makes it very simple and I have all of my stoich values ranging from 14.5 to 14.9 on the WB. Then at wot I'm a steady 12.9. Now this will change slightly from day to day because air charges change with baro pressure. You can tune every day if you want to, you'll never be 100%, 100% of the time.
What this does is make it quick, accurate and out the door for the next one
The only reason you don't need ve is because you run a MAF. Your car will only reference it if there are HUGE differences between the VE table and your MAF. VE tuning is good if you want to put the time into it, but leave it till the end. There is a lot more to do first. Now, you can set up your tuner to show error % in ve as well, so it could be done very easily. Point is, when the MAF eails on our 3400's the car will go SD! I would not drive 5 miles in SD, my 2 cnts.
I know you will have lots to say about this but have at her bud, I am always willing "TO LEARN"...hahahhaha

[sprucegagt]

This is how you tune a V6:

There seems to be allot of methods to tune the AFR on the V6 cars. Since these cars don't yet have an open loop table like the V8's and the V6 (4.3) trucks, the commanded AFR while in open loop is all over the place when not in PE. In PE the commanded AFR will be were you set it.

When is the car in open loop mode yet not in PE?

When going to wot from a dead stop there will be a lean spike at first (under 7500 hz) that is normal if you first got you part throttle AFR right, this is caused by the split sec. delay for the richer exhaust to reach the wide band.

The lean spike is from AE and PE enable being out of adjustment, not a delay in the enrichened exhaust hitting the wide band O2. Think about it, if the engine was enrichened at the proper time you would not have a lean spot.

[torq455]

ohhhh well DUH!!! why didn't i think of that!!

[MMGT1]

It works!! Getting that 14.7 is key with our cars. Unpluging the "factory 02" puts the car in open loop without having to go SD. (very hard on trans!!) Once the 02 is back in the trims will be very cose and WOT will be "PERFECT".
This dissables all trims in the OBD2 as well. No need for trims when you tune with a wideband...

[SappySE107]

Interesting method. I haven't heard of that one but I don't tune OBD2 so I am not sure how the computer reacts to what you are doing by removing the O2 signal to the ECM. I know the OBD1 would take your - LTFT and add it all back to 0 (128 in obd1). This way it would only add fuel. If your LTFT is adding, it would keep all of that. Sounds like its less safe for 60V6 OBD2 if you can actually lean it out more using your LTFT from cruising around.

[MMGT1]

"Lean is mean" the saying goes. The sweet spot for torque on gas burners is 13.2:1. I run 12.9 @ WOT to keep it safe. This is from 7000hz to 11500hz. The most I see is 9000hz but you want to smooth the table the rest of the way up.

This is how you tune a V6:

There seems to be allot of methods to tune the AFR on the V6 cars. Since these cars don't yet have an open loop table like the V8's and the V6 (4.3) trucks, the commanded AFR while in open loop is all over the place when not in PE. In PE the commanded AFR will be were you set it.

This is what I found is the best way to tune these cars. First leave the VE table stock. Then zero out the Power Enrichment PE Enable > Delay vs. TPS table (some models will already have this table zeroed out). Set the PE Enable TPS > Hot to 0% (at all rpms). Set the Base AFR vs. ECT to 14.7 at all temps. Zero the Add vs. Tps (note the values in this table add to the Base AFR vs. ECT and leans the AFR). Then zero out the Add vs. Rpm table.

Now install the wideband in place of the stock front 02 sensor, or the right front if a rear drive car (this will put the car in open loop). Flash this new file, then warm the engine to operating temp. Start scanning and reset the fuel trims. Now the commanded AFR will be steady at 14.7. With the Maf AFR histogram open, drive the car at part throttle to fill the histogram up to ~7500 hz. Try to accel & decel smoothly. Then copy & paste the Maf error % histogram to the Maf table using paste special multiply by %. Once you get the AFR close to 14.7, then use paste special multiply by % - half. For the low end of the Maf table that you didn't enter, just enter the error % from the lowest airflow hz cell that you did enter. So by now the part throttle AFR will be ~ 14.7.

Now change the PE Enable TPS back to stock (or were you what it as some models have the low rpm enable at 100%). Change the Base AFR vs. ECT to 13.0 at all temps for NA, or 11.5-11.75 for a boosted engine. Flash this new file, connect the scanner and check & reset the fuel trims. Bring the car to a dead stop, use the VCM controls to put the trans in 2nd gear. Now go wot till your max rpm desired. Then copy & paste the Maf AFR error % to the 7625 hz & higher part of the Maf table. For the freq. hz cells that the scanner skipped over, just average these cells. For the higher freq hz cells of the table that you didn't enter, just enter the error % from the highest airflow hz cell that you did enter. Once you get the AFR close, use paste special multiply by % - half.

Unlike the V8's and V6 trucks, if the part throttle fuel trims are negative by even a small %, you could have negative LTFT at wot. This is why you need to get the open loop part throttle AFR close to 14.7 BEFORE wot tuning the AFR.

When going to wot from a dead stop there will be a lean spike at first (under 7500 hz) that is normal if you first got you part throttle AFR right, this is caused by the split sec. delay for the richer exhaust to reach the wide band.

Now install the stock O2 sensor. If you did everything right, your LTFT's should be close and will lock at 0% @ wot.

[SappySE107]

You would have to run it on the dyno and see what the engine wants for your 20 second burst (which better be more than 1/4 mile!). I found on the 3.1 (obd1) that it liked to be richer down low and lean out at higher RPM. That could be because of the stock tune being richer in the MAP tables too:P

[torq455]

so if the AFR were to stay at 12.9, for a once in a while 20 second WOT burst. that would be better than a decending AFR? like i said, i don't get much of a chance to even run a full 1/4 mile.

[sprucegagt]

/\ Finally one of them is seeing the light! lol

Help! 04 GA SE 3400 with a couple of external mods only. reprogramming the pcm and need to know what AFR to command. Supposedly, say during the 1/4 mile it starts at 12.9 and drops to 12.0. From what I hear, the command vs. the actual AFR is different. What should I program this at?

As others have said you will need a wideband to get an accurate AFR. The reason why the commanded AFR is different from the actual is the MAF table being off while your in PE. If you had a wideband you can correct this so the commanded AFR does match the actual AFR.

FYI, the stock PE commanded AFR's are to aggressive in the 04 GA. You don't need to drop a full AFR point while at WOT unless you plan to be on it for more than a minute.

[SappySE107]

Elevation, quality of local gas, how close GM was to spec (tolerances), etc. Tons of variables. The deal with the commanded AF is that it uses calculations based on the tables, the +- fuel trims for long and short term, and your spark timing which is only variable upon knock. Its open loop. So while its not accurate to read the narrowband O2, its also being ignored by the ECM as well.

This is why you don't tune WOT first.