I finally got the 6.0 in and all hooked up. The 4.8 program starts it, but it will not idle by itself. It runs fine if I hold the peddle at 700 rpm. I tried to adjust the IFR in both directions, but it still doesn't want to "catch". Is this because the cam profile is so different? Any ideas on what I could try next?

 

just for the hell of it, unplug the tps sensor, turn the key to on, wait 30sec or so, turn key off, plug it back in and try it.

 

That's a good idea. I didn't even think of it. I'm gonna go try it. If it works, you've become my new best friend.

 

Check that the IAC valve is working correctly too.

 

sounds like you have the ability to tune it? just turn up the idle to 800 or so so it will run. then over the next couple of days start bringing it down till you find the lowest it will go and still run good.

what cam is in there?

 

What tuning software? I can send you the stock GM idle settings (or heck, the stock tune) for either HPT or EFI.

 

you should set the ifr to accomodate the larger injectors and leave that alone just go by the ratio from the old to the new injectors and increase accordingly, set it and leave it.

Then start looking at ve table and maf. Honestly I would just go onto the horist site and get a stock 6.0 bin and cut and paste then go from there.

Are you runnin and aftermarket cam, heads, intake need mod list.
NA?

 

The cam is a comp xr269. The heads are stage 3 6.0 with 2.08/1.60's. Stock intake. I'm running HPT 2-bar SD. I did get it to idle, but now it feels like it's not running on 8 cylinders. Number 5 and number 7 plugs are getting fouled quick, smells like gas, but could be oil.

 

I would bet your ifr table is way way off, very rich. Unless your runnin bigger than stock injectors I would just use the stock values. DONT TUNE FUEL TRIMS WITH THE IFR TABLE. With the stock 6.0 ifr values in there I would also put in a stock 6.0 ve table and maf, multiply the whole ve by .8 go from there, tune in SD. i WOULD SET ALL TABLES HAVING TO DO WITH AIR AND FUEL BACK TO STOCK (6.0 values). I would think that would get you back in the right direction.

update us on what your trims look like after youve done the above

I would also multiply cranking ve by .75 also

 

I'm running 43lbhr injectors. I also have a p1sc procharger on it. I have the 4.8 program running it now, with only minor changes to the tuning. I running speed-density, so the MAF is doing nothing. I don't know what my problem is with the 2 cylinders not running right. I've tried everything including changing plugs, wires, and even the coil packs. No vacuum leaks that I can find. It was running pretty good last night, but today it's running shitty. The fuel trims are not that far off. It's adding fuel in some places and subtracting in others ( not a whole lot , though either way). Could the timing be WAY off do to the dramatic change in cam profile?