What AFR?

[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.

[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]

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]

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]

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]

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]

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.