On WinALDL when your O2 volt readings go up and down which is richer and which is leaner? I know that .450 is 14.7:1 but don't know if when the number get higher(say .645) or lower(say.269) which is rich and which is lean? Reason I'm asking is I'm going to try to adjust my fuel pressure like the tech article on here says to. Thanks, Bobby

 

higher than .450 is rich and lower is lean. You won't be able to tell a difference when you start tweaking the fp because the ecm will correct for it. Now when you go full throttle or start it up in the morning it will be peg rich or lean (depending on which way you cranked the fp) because that is when the ecm ignores the O2 and runs open loop.

If your not tuning your chip then leave the fp alone.


edit: You can however make minor global changes with the fp, but you don't want to be looking at the O2 to do that. The ecm just uses it to maintain 14.7 You want to be looking at your blm's These are what the ecm uses to correct the fueling. Less than 128 is rich and more than 128 is lean. You want to go to the blm table and set it to wide avg. then drive the car around for a while and try to fill up as much as the table as possible. Then take a look and see if most of the table is above or below 128. Now once you start playing with this you'll start to appreciat the ability to change each individual entry in that table. Thats when you'll order your chip burning equipment.

 

Yea I think that I'm going to order the Romulator now. I've got the laptop, a Y-cable to hook up to ALDL and OBDII plugs(I've got a '97 Z28 with a OBDI conversion PCM in it also). So with the Romulator I'd be able to start changing the ECM on the fly huh?

 

Monte: why do you suggest wide average? i have been using narrow average. i assume narrow ave throws out the highs and lows whereas wide ave uses more samples including the ones that are high and low of median? i would think some way off are anomolies?

 

For some reason it seems like the narrow avg just doesn't look right to me. For ruffing in the VE the wide is better. I've just gotten my VE pretty close after getting my IAC valve working correctly. I'm still using the wide avg even though I'm +- 2 blm's. I guess I'm still using it as a habbit. The narrow avg looks about the same as the wide now that the VE is close. Seems like the wild hair blm's don't effect my tuning as much as you would think. Then again I do long logs (mostly an hour) on my way to school so it sort of avg it's self out. Guess it's a preference thing.

 

Good info. I was always curious which values others used. BM, what do you think that when your at a stage such as you, being + - 2 BLM's, of locking the BLM's at 128 and tuning off of the INT values. Have you or anyone else done this?

 

From what I have read once you get your blm's within 10 you can go ahead and lock the blm's and start tuning with int's if your carefull. I really don't think getting my blm's any closer is going to be benificial or even possible. Right now my car will start out about 2 blm's lean when it's warming up after the initial startup, or for about the first 5 minutes of driving. Then it levels out at around 128 then goes about 2 blm rich after i have been driving for a while like 30 min. I guess it's once the engine starts to heat soak it changes the way it behaves. My VE curve looks very smooth and about the way it should. I'm happy with it the way it is.

I have though moved on to tuning other things and keeping an eye on my blm's to see how they effect them. Pump shot for instance. I'll drive my car on the highway for a while and save that blm table then go around town for a while and save that table. I'll then compare them. If I have too much pump shot then my around town log will have lower blm's. Once they are about equal I know I have it right. I have also started watching IAC steps at idle to tell if I'm getting the int delay, prop gain, and prop duration tables all in the ball park. I have always had decent blm's at idle but it smelled stinky. So one I got the IAC working correctly (which wasn't that long ago ) I would start with one table and tune it till I had the lowest IAC counts and still had a blm of 128. I started with about 60 counts and I'm down to around 24 counts with out ever touching my VE curves. Just from modifing the int delay. The whole time my blm's never moved. I still need to play with the other stuff.