Originally posted by Tired2
I did ground the MS to the block and to the maninfold, but I ran all my sensors directly back to the MS box. Supposedly grounding sensors at common engine ground points can give inaccurate readings, especially when other systems are pulling a lot of current. I would try to get each sensor, or maybe start with CLT and get it back to the ECU and see if that helps. If you built your own ECU, check the bias resistors for those sensors, if they are the wrong value that will mess you up also. Both sensors are important, CLT will help calculate how much warm up enrichment you need, and how open/closed your IAC should be (it closes more the warmer the engine)... The IAT is very important also, because it helps calculate the mass of the air going into the system. PV=nRT, what I have affectionately named "perv-nert" is the ideal gas law equation.... the T is the temperature converted to kelvin. So, if you have an artificial increase in T, you'll have a proportional decrease in 'n', which is the amount of air you have in moles. That artifical decrease will make the ecu put in less fuel. So, if you get your AFR correct with bad sensor data, when the sensors start working correctly later on your tune will be junk again. I'm not sure this is new, but just a good chance to bring it up for those who have not researched it. P is pressure (MAP), and V is volume of your cylinder(s). R is the ideal constant.

Cool I will check it all out this weekend. I will run the two gauge grounds directly to MS and not the common point between MS and the battery.

Thanks for the advice and the physics lesson ;) I actually understood all of what you said! haha