So I want to have the ecm control the fan, how to patch that into stock $61 code.... do I use the EGR since the code is already there for temp? Or do I use the air pump AO? I want to do source code but lockers is too good to get rid of just for romless.
I have some ideas, I'm just getting everybody's opinions.

 

I actually tried to use the EGR stuff as is in the $61 code. Needless to say, it didn't work too well. I wired the fan relay to the EGR solenoid and set the temp constants to ON at something like 210 and off at 185 I think. The fan would come on as soon as I switched the IGN to ON...and then it would switch off when the engine was running. If I turned the engine off and left the IGN on, the fan would come back on. This was with a warm engine (i.e. up to running temp range). I thought it was kinda weird that it acted like that. I was going to try to use the speed constants to turn the fan off at highway speeds of 55 mph and up. That didn't work either for some reason. Maybe I had something screwed up in the constants. I used the A/D temp values to set the constants, so I really don't know what I did wrong.
I also think that there is some level of fuel control that is contained within the $61 stuff. I am sure you know this better than I do, though. That section of code may need to be removed or rendered inoperable.
I am in the same boat as you are as far as going romless is concerned. I really don't think I am at that level of expertise just yet. If you come up with some kind of patch that can be burned to a chip and tested, let me know. I'll help you develop it where I can.

 

Lockers works with ROMless.

Wire up an adapter and try a P4, then you can run, the stocker, the ROMless, or a P4. Then you can do real comparisons and see what you like/ works best.

 

I love those airpump outputs. Thats what ive been using for my fan control adn whatever else I wanted. I suppose you could use the EGR as well. I didnt really look too closely but the egr is pretty global in that a good deal of things happen when its on. The airstuff is nice in that its all self contained but you have to go romless to use it since the actual control for the airpump outputs stuff as well as all the code is out of your reach. I suppose you could play with the quals for it to get the fan to come on with speed or possibly temp but there is a bunch of stuff that controls the outputs like max rpm, O2 limits, etc. As you probably already saw, since I couldnt use lockers I went with a turbocharged ALDL using one of the unused outputs. At 38,400 baud/8 fps its not on par with lockers but it still allows for reasonably fast datalogging while having the customizability and flexibility of being romless, not to mention the fact that the cable is real simple for it. Just a serial connector and a resister. Easy to use and quick, but not the magic bullet. You could keep the edge connecter still functional by jsut building a 'romless' adapter that fits in place of the present prom. Dont know what changes would have to be made to use it. I built everything onto one small project board for the testbench ecm and it could easily be soldered in place of the prom and still look clean and be reliable.

 

My vote is for EGR, but that's just me. Here's my reasoning;

I have my AIR pump still, and *one* of my air valves. I use the one air valve to divert between aircleaner and the cat. The other air valve wire I use for my IAT, since it's in close proximity of where the other valve was. EGR is still hooked up on mine, but of course completely useless because I have no exhaust crossover in my heads (L98 aluminums.)

I'm trying to keep things at least looking like they function properly; they do visual inspections here in Texas and I want them to think it all works.

If you DO decide to go with an air valve, use the air DIVERT valve, as I'm using the air SELECT valve wires for my IAT.

 

How are you using the AIR DIVERT valve wiring for the fan? I tried the EGR ($61 code) and it simply doesn't work like I thought it would. I used the EGR solenoid wiring to control the fan relay. Does the AIR DIVERT work differently? If it works better, I'll give that a shot to see if it works for me. Having the fan controlled by the ECM would be great and it would eliminate one more switch on my dashboard.

 

Yes, the air divert is a simple on/off output. Easy to use. Youd have to take control of it away from the AIR emmisions control routine, though. Dont see much way to use it otherwise.