Here is the deal. I have a 350 that I put vortec heads on, GM performance intake, comp cam(comp cam XE249H-12, INT@.05 206 and EX@.05 212 Lobe sep, 112), full length headers, 9.6 to 1 compresion. The throttle body is all stock, with a custom chip from FastChip. I have a fuel ratio gauge and it bounces from 13.5 to 14.5 at high way speeds and 12.5 at WOT. It is running rich and fouling up my plugs, the milage is 5 mpg! It runs rough at idle and does not accelerate very good. The engine before was all stock and it ran great, except for the cracked head at 210,000miles. This is my first experience with FI engines. Any ideas?

 

Does the chip need more tuning? I have been trying to see if I can get the chip reburned or something by fastchip. Has anyone else used fastchip? Is the throttle body tunable at all? I put in a 195 term. stat trying to lean it. 160 was a little too cold when it is -20 F. Didn't help at all. Any help would be appreciated.

 

Welcome aboard...

*Insert scratchy broken record sounds* 'You really have to buy the prom burning equipment and do it yourself.'

I know thats the first time youve heard that but thats what everyone else will tell you. The only one who can really tune your car right is you since your the one who has access to it. Theres more to tuning then jsut giving someone some numbers. The engine's behavior, feel, and drivability is about 60 percent of it and guess work or some data logs really wont bring that to light. The 'tuner' who burned your chip probably added lots of fuel either in the form of raising the bpc or bunmping up the ve tables in anticipation of your engine needing more fuel. In reality, the engine probably needs relativly less fuel at low loads/speeds then the stock engine did since its operating band and volumetric efficiencies have shifted due to the cam. The heads and improved exaust really change things as well. Go over to the DIY-Prom board and flip through the stickies. In there are some good links as well as a link to an intorductory prom burning article that will walk you through the mechanics of prom burning and tell you what you need to get.

 

Make sure that your timing is at 0deg, and that you do that with the timing advance wire unpluged.