I've built a new motor with some serious differences from the motor that the computer was tuned for. Everything from cam to the intake manifold to a .2 liter increase in displacement. The car ran just fine with a healthy bump in fuel pressure for the first 3000 miles. I noticed that after that the motor's sound changed, you know after the motor loostens up after break in, the tune went to crap. Just out the blue. The car just wanted to run rich all the time to the point where it wanted to shut off when I came to a stop. I turned the fuel pressure down to 40 psi and the car is driveable again. It's starting to warm up down here in florida and I've noticed that the car runs so mcuh better now that it's warm. The only difference that I can think of now that it's warm is that the intake temp stays warmer and my ect is more stable. The ect does drop down do 180 when I get on the freeway. Probably has something to do with the huge Koyo radiator. I use a hondata heat sheild gasket and I don't run coolant through the throttle body and IAC motor anymore. Supposed to get the carm tuned next weekend but neeed to make sure that it's not something else before I go. Any ideas would be appreciated.
Your ECU 'thinks' it is too cold and adds 'cold start fuel'. Reconnect the lines to the IACV valve and have them disconnected for better performance only in the summer.
don't understand. If what you're saying is correct I need to take that heatshield gasket off as well. The instructions suggested disconnecting those lines because the lines would heat the manifold and render that heatsheild gasket useless.
It is not same thing. When the IACV is not properly heated, the ecu thinks that the engine is cold. Keep your gasket and use teh bypass only in the summer. You should have no problems.
Just out of curiousity. How does the ecu get fooled because the the IACV isn't heated? I mean how does that affect the IAT or ECT reading going to the computer. Does the computer make that assumption by using some other data than IAT or ECT? I'm pretty confused.