AE/DE vs VE tuning

[discostu]

Ok my tune is getting pretty close now, between 126-130 BLMs in almost all situations. My INT is pretty close too, with a couple small exceptions.

My question is, for high load situations (60+ kpa) how do you tell when you need more VE versus having more AE? Same goes for decel tuning, how do you know you need lower VE rather then having more DE?

I think the proper way to tune high load VE would be going up a rather large hill so you can get those high load situations without getting into the AE too much, but I don't have any good hills near me that would suffice. Is there any other way? In a small car like mine, I have to give it good throttle to hit 70 kpa so it kicks in the AE quite a bit.

Same goes for DE, do you go down a long hill and cruise at 20-25 kpa to get those low load situations without hitting DE?

Also, what kind of INT values are you guys seeing when your DE kicks in? Under hard decel my INT goes to about 140-145 and hangs there until I change gears or touch the throttle. I'm not entirely sure what I should be seeing there, but I think that's pretty good. Of course, this is only for tuning, because I normally have DFCO enabled. My main concern is the AE tuning at this point.

[Mars]

Not sure what your setup is, but I have 30# injectors and I scaled the whole AE table down by something like .6 or .5. and it helped ALOT as far as tip in hesitation goes.

I tune AE with the wideband, I found that to be the easiest....

As far as loading up your engine, you can use the brakes. I've gone through several rotors and pads while trying to get my tune perfect...

Surprising how a boosted 660 has about 5X the power of a J-body braking system.

[Joseph Upson]

Not sure what your setup is, but I have 30# injectors and I scaled the whole AE table down by something like .6 or .5. and it helped ALOT as far as tip in hesitation goes.

I tune AE with the wideband, I found that to be the easiest....

As far as loading up your engine, you can use the brakes. I've gone through several rotors and pads while trying to get my tune perfect...

Surprising how a boosted 660 has about 5X the power of a J-body braking system.

Setting up a by pass circuit to prevent cruise control deactivation while braking was how I intended to load my engine to reach the higher Kpa ranges for tuning a selected rpm range. After further thought I realized with the 6 spd transmission I may not have to by just shifting to 6th gear at a low speed which will help hold an rpm range longer while braking and trying to reach 100 Kpa.

I see the braking theory works though as I expected. It should also help with maximizing the spark table also.

[Guest]

I think I'm just going to build a dyno.

Tune in the comfort of my own garage.

I've seriously been thinking about this for years, now I have a reason to.

Anyway.

AE, can be a tricky one to tune, and Mars is right, using a WB will help get it close, but also how it feels, how it smells and reacts also need to be used to tune.
AE is simply used as a transitional helper. Going from a steady state to another state. In the carbed world this would be refered to as "pump shot", adding some fuel when the throttle is moved from it's current steady state, to help the engine accelerate.

PE is used after AE or starting at the tail end of where AE will let off, to keep the engine accelerating, and engine that is accelerating needs more fuel, than one staying at a steady state for the same load and RPM. PE is almost like a long term AE, where adding more fuel allows the engine to have the fuel needed to get higher in the RPM band.

VE is what is the base of steady state. Essentially for the VE table you would need to hold the engine at the same load and RPM for to tune the VE table to where it should be for each point. I know you're thinking that anything at 100 Kpa or above will never be steady state, which may or may not be true depending on the application, and even still, the VE table is tuned by steady state loads. It can be tricky to tune the VE table and usually takes a lot of time to get the higher load and RPM areas tuned just right, for the DIYer.

[Superdave]

I've been working on Xbot's tune for a 3400-auto, after finally getting enough fuel in PE he kept getting KR when he'd slam open the throttle to go WOT. A few adjustments of the AE tables and it's getting better. I'm just watching the NB values on this. In this case i've had to add more AE where usually you'll have to subtract with bigger injectors.

His NB voltage would go to .3 and below for a few secs, then run up to .950, the KR would decay pretty quickly but pulling 2 degrees of timing affects overall power.. and a lean spot is never good.

I still believe that he's got fuel system issues though...

[discostu]

This is great stuff. My setup right now is a bone stock 3.1L/5 speed Z24, so overall the BFUZ mask was relatively close to begin with.

I think I'll try the braking thing to tune the higher MAP cells. I have no cruise on this car, and I never hit WOT/PE because I'm using a stock 2.8L clutch at the moment, which breaks loose at about 40% throttle.

I'm just trying to get maximum MPG out of this car and gain tuning experience right now. I've picked up about 2mpg city through tuning and probably 3-4mpg highway and I've still got lots of tuning in me.

[torq455]

try locking the BLM at 128, then tune the INT. that takes a lot of guess work out of how much VE to change. tuning VE is tough and does tend to vary some day to day. i have the KR with slamming the throttle too, but i just figured i was adding too much timing. i have the auto and just after a low rpm shift from 2200 to 1200, INT goes to 135-140 and quickly returns to ~125. i still have that fast off idle tip in hesitation as well.