Diving in head first, mind the rocks...

[robertisaar]

8300 RPM lifters.... interesting that the VE and spark tables will end at 8400.

are you still running the factory rear brakes Jon? using the calipers/brackets from a 94(except lumina)-97 1G W-body was a worthwhile upgrade for me.

[SappySE107]

He has corvette brakes, 13" front, 12" rear. Its a wicked setup

I just want 7500. I need to modify the intake manifold and put headers in for 8000+, and I don't think my GP is the right vehicle an S2000 type powerband.

[pocket-rocket]

I don't have an appropriate ADX for TP, but that's ok. I think my 12 year old laptop power adapter just took a crap on the floorboard since it was making sizzeling noises. I guess the new laptop idea either made it mad or is really good timing. The ADX I'm using right now (because of the lack of another) is the one for nAst1, so for fuel trims it doesn't show the actual INT value, it shoes a gauge and 1 is center and it floats back and forth.

I still feel like I have no idea what I'm doing, though. I did find out advancing spark (in small amounts) on the cells the ECM was hitting did smooth the idle out. I didn't go very far, I didn't want to screw something up.

[pocket-rocket]

He has corvette brakes, 13" front, 12" rear. Its a wicked setup

I just want 7500. I need to modify the intake manifold and put headers in for 8000+, and I don't think my GP is the right vehicle an S2000 type powerband.

I don't think MGBs are the right vehicles for 3500s that wind up to 7k either

[SappySE107]

The int value you see is percentage. 1 is 100% perfect What is your spark advance set to now? about 20 for all idle areas works well for me. Set it to 10 and make it rich if you want to hear a cammed 3.4 DOHC.

[pocket-rocket]

I think it was around 21.xx, although the stock table looked like it was around 24. I may up it some and leave it because it did sound better. I know 15 made it cranky, lol.

I was trying to get the ECM to stay on for a minute and turn the fans on for 10 just to see if it would leave the fans on when it's really hot out. I had the temp enable set really low, but it didn't turn the fans on when I shut it off. Does it have to already have the fans on for that to work?

After sitting here I'm considering putting a new cat on this thing as well. Earlier I can only assume the Ostrich freaked out and it lost the connection to the laptop and started dumping fuel like crazy enough to get it to smoke at idle and leave the SES light on. I'm going to have to go back and check my socket connections at the MEMCAL methinks.

[SappySE107]

I have never had the ostrich work on a GM computer, so I am surprised when others do it. Higher idle spark gives more torque but it gives less room to up the advance for AC load. What is your idle speed set to? I think I am 800 commanded with OBD2. If you up the spark, the iac has to come down to keep the idle speed the same.

The fans won't stay on with the key off. I don't know that I have seen that option in OBD1.

[pocket-rocket]

Yeah, I'm able to update the ostrich and watch the engine parameters react all at the same time right now, it's pretty sweet

I think it's commanded @800 atm.

[robertisaar]

The fans won't stay on with the key off. I don't know that I have seen that option in OBD1.

even though i've seen the stickers on pretty much every electric fan equipped GM car implying "fans may come on at any time", i don't think i've ever seen one that did it either..... probably wouldn't be too painful to add in.

EDIT: problem: the +12V from the coil side of the relay is powered by the ignition switch being in the run position(ECM grounds the coil). that would NEED to be moved to a constant +12V to work with key-off.

[pocket-rocket]

Nice, so it's something simple.

I'm back in the saddle (passenger seat, lol). Laptop died, I hit the adapter with the heat gun. It's amazing how a heat gun set to 1k*+ can loosen that glue holding the case halves together. At any rate, the 110v in had broke loose somehow. Probably from dropping the thing. At any rate, the adapter is fixed.

I guess grabbing that .doc of the DF stuff off the site would help me understand what I'm doing? I mean, playing with fan temps, idle spark and such is cool and all seeing it actually have an effect on the engine running, but I still don't understand how the ECM reacts to VE table changes. I can see what cells it's hitting on the map (really snazzy feature, I like it), but I'm not sure how the ECM actually processes that information to make changes to the engine fueling. I know raising a value tells the ECM the engine is more efficient at that RPM at that vacuum, but how does that equate to making it richer or leaner?

Where's the GM ECM tuning for dummies book at, btw?

[robertisaar]

think of the VE table as a multiplier (since that is what it equates out to in the algorithm).

a VE of 100% means at whatever RPM and whatever MAP, 100% of calculated maximum theoretical air is entering the cylinders. for a 3.4 liter engine, it's 3.4 liters of air total, and for simplicity, let's say it's at barometric pressure as well. so you have 3.4 liters of air at baro pressure (not sure what that would calculate out to as a mass, but that's more advanced) in this 3.4 liter engine. with a VE table set to 100%, the ECM calculates the mass of the air in the cylinders, and knowing the injector flowrate, calculates how much fuel is necessary for this airmass.

if you had a VE of 50% in the same cell, the amount of fuel calculated to be necessary would be cut in half, since the ECM is being told that the cylinder is only filled with 50% of the possible airmass that the cylinder can possibly hold (over 100% would be.... uncommon, but possible).



that, in a nutshell, is how the VE table works. there are a lot of other variables that come into play, like coverting the volume of air into the mass of air, but almost all of it is based off of the principle of multiplication, most of it being a range of 0-1.

[pocket-rocket]

>.>

Wow... So simple. I figured it was something more complex than that. Now I really feel like a noob.

So if it's rich, lower the VE, the ECM cuts some fuel.

I guess I'm also looking for the thing to be more off at idle than it is, that way an improvement I make will show good gains as far as the data coming back from the ECM goes. I should have had Ben show me this stuff before he left... :/