I have a 99 civic si. Mods include: JRSC, 11 psi pulley, Hondata s200b (max boost map), RC 440's,Aem fpr, Walbro 190lph, and IHA.

My problem started before I upgraded to the Hondata and the AEM fpr. It's a liitle difficult to start when cold but very hard to start when I have run the engine then let it sit for a while. I also notice that when I shut down the motor that my fuel pressure drops about 1psi per second. Fuel pressure is set to 43psi static and does not fluctuate at idle. Vacume is a steady 17psi at idle.

Here is what I have done to try to eliminate or identify the problem. I temporarily swapped to a stock regulator, I diconnected the purge valve, I replaced the plugs(.38gap), checked compression (198, 198, 198, 195), upgraded to Hondata, adjusted timing to 16btdc.

When the car finally starts, It runs extremely rich and smokes for a couple of minutes and then idles fine. No smell or sign of fuel leaks. Could my injectors be leaking internally when the motor is cutoff, thus causing the fuel pressure to drop? I'm stumped as to what else it could be. Please help.

 

Sounds like one or more injectors are leaking. When you shut it off they dump fuel into the engine until the pressure drops far enough. That would be the cause of the hard starting and rich running when warm. The hard start when cold may be due to no fuel in the lines until the pump pressurizes the system. There's a couple of places that will rebuild and flow match injectors for about $50 each. If you need the names, I think I can find them. Were they new or used when you installed them? Did you have a rising rate pressure regulator before the hondata? The higher pressure needed may have hurt their ability to fully seal. If the system was tuned when they were leaking, you may need to have it re-tuned for injectors that seal properly.

 

The Injectors were bought new from ImportParts.com about 6-8 months ago. I removed the JR RRR when I upgraded to the 440's and Zip's SMC. The injectors have not seen more than stock fuel pressures. I first thought it was the SMC, but eliminated that as a cause when I went to Hondata. Also I wait 5 seconds for the car to prime before starting. My guess for hard starts when cold is the excessive fuel leaked down into the cylinder from the day before. Is there a warranty on the injectors? Thanks