FAST, VE and AE vs. The World ???

[Jackson]

I'm working on the getting the baseline VE table down and experience some oddities. Anyone have the ABCs of establishing the VE table?

Respective to AE 'Rate of' tables I take form that its only when TPS and MAP are designated to be moving. Today I was in the empty warehouse parking lot holding 1st gear though 900, 1400, and 1800 rpm to see where VE wanted to be at. Generally I was looking for a strech of about 5 seconds where the MAP sensor was fairly constant (+- 1 or 2).

The motor will idle decent in the 14.4 range and accelerate ok. However, I'm curious as to why VE cells near the idle area are in the 69 to 70 range. This seems a bit high?

Any ABCs of getting VE base established?

For the most part, I can get the motor to slowly rev smooth when in neutral. I'd gather the AE vs. TPS rate of change is close. However, under light load I get a tip in condition. I'm looking to adjust AE vs. MAP rate of change.

Edit: My TPS at idle hangs around 14% and 96% WOT

Where does AE ve. TPS position and AE vs. Coolant come into play?

 

[Ricky Trussell]

I run almost no AE/ coolant temp. This is self explanatory as far as fuel added when the engine is cold and you are moving.

The AE/TPS position controls what % of all AE fuel the engine gets. This should be a declining line from left to right. Say 100% at your idle TPS position then angled down to the right corner to about minus 40.. this is a base setting and you tune from there.

 

[Jackson]

Ricky,

I snagged a professionaly tuned FAST config and saw some differences. It pointed me in the right direction and handled a lot of the throttle / tip-in related issues.

My main question though, how are people tuning the VE tables?

Nearby is an open warehouse parking lot. I'm taking the car out and holding it at a particular RPM to where hopefully any 'rate of change' enrichment is out of the picture. Its got a fully manual TH400 with 'brake. Its been a case of driving the lot while holding 1300 rpm, 1800 rpm, 2300rpm, and 2700rpm. Does this seem reasonable? Thoughts? Ideas? Suggestions? So far so good as the car is responding well. Tuning the FAST is getting to be a bit more fun now.

I'd like to get on a chassis dyno where the drum brake can introduce load the the wheels and hit a diverse range of MAP and RPM ranges, focusing on single cells.

 

[Ricky Trussell]

If your car is street legal get a friend to drive on the interstate at and you tune. Or get out in the country and drive. It is easier this way but I have rode around by myself and tuned with the laptop in the passenger seat. Use different gears at steady rpms to tune. Most say +- 5% is okay.
You can log WOT runs and then lay it over your VE table.
Just make sure you are not letting your 02 take over 5% at WOT.

 

[Jackson]

I've done a little bit of road tuning with some decent results.

I plan on doing most of this on the dyno and using the dyno's drum brake to introduce load. This should be a very controlled environment.

I have tried to get MAP and RPM constant so I can focus on a specific cell and avoid any sort of 'rate of change' enrichment on the cell. One person I was talking to suggested turning closed loop correction off entirely to do this. In this situation they don't want any correction factoring in. Thoughts?

 

[Ricky Trussell]

I like seeing % of correction from the 02. Sometimes there is two cells that need to change. I know the one cell tuning theory but staying in one cell exactly is hard. Make sure your cells are smooth transfers. Like 5-8 numbers difference.

 

[RickWI]

Originally posted by Jackson
I've done a little bit of road tuning with some decent results.

I plan on doing most of this on the dyno and using the dyno's drum brake to introduce load. This should be a very controlled environment.

I have tried to get MAP and RPM constant so I can focus on a specific cell and avoid any sort of 'rate of change' enrichment on the cell. One person I was talking to suggested turning closed loop correction off entirely to do this. In this situation they don't want any correction factoring in. Thoughts?

If you go to a dyno you need to make sure it is an eddy current dyno. If it is a dynoJet inertia type dyno you won't be able to control the drum, it will burn out the brake on the drum if you try and do that. If the dyno operator has any knowledge or common sense he'll just say no. If you try and tune on a typical inertia dyno hoping just the weight of the roller will help you, it won't, you simply won't be able to control and hold speed. Been there, tried that, didn't work. Superflow makes a great Eddy Current dyno. If you can find one of those in the area that would be the ticket.

I have always tuned in the VE while in closed loop. Why in heavens name would you want to tune in open loop. In closed loop you look at your correction factor and use your percent key and dial in that cell. Simple and pretty goof proof.

Dopn't know of any other way to dial in the VE table other than what you are currently doing. It does help to have a buddy that is car savvy when you do it on the road. An eddy current dyno will get your map pretty darn close and would be the easiest it sounds for you. The inertia will only serve to tell you what you make for wide open throttle power.

 

[norbs]

I sometimes tune in open loop, since you have to remember the o2 corection has a lag time of about .7 seconds, throwing your readings off. In open loop you dont have the o2 introducing fuel and screwing up your readings. The closed loop way works also too, but i like to be different. You could go open loop and see your actuall a/f readings and record them and get a very accurate picture of whats going on.