On 09:52 PM 12/22/02 -0500, George Freeman said...
I saw a guy at the track making adjustments to the fuel pressure regulator claiming it made the car run better due to richer/leaner mixture. So my question is, how does the fuel mixture relate to the fuel pressure regulator? I thought the fuel mixture (or fuel map) was preset by the ECU, correct?George '89 DX-Hybrid-D16Z6, 127k miles "Seats, Suspension, Engine, MSD, next=heat reduction!"
On my past carbureted engines (single, dual and quad...), I use to run a Holly fuel pressure regulator. It served mostly to regulate the fuel PSI from the electronic fuel pump (one made by Facet) to my Weber's.
Sometimes when I felt that the engine was suffering from fuel starvation, I would increase the fuel PSI. I would almost always have to re-sync the carbs in order to get them to idle (which in some cases was nearly impossible, I would have to deal with a fast idle...) and sometimes advance or retard the dizzy a couple of degrees.
I would also record the settings in a notebook which helped me dial the engine in when I use to run at the track (AutoX, Open Track, etc...).
As for the Honda CRX goes, I was told that ECU would adjust itself automatically... Or at least try too... I have not confirmed this claim.
This is where a programmable ECU like the ZDYNE or Jet would be really nice.
But speaking in general terms, the "modern" EFI does make adjustments to cope with the variables (i.e. increased fuel PSI) and it does it fairly well.
On my wife's Audi, I installed an adjustable fuel pressure regulator (mainly to replace the stock fuel pressure regulator when it went belly up.. the cost of the adjustable version was not all that much more than the stock...). I think the stock regulator was set to regulate fuel PSI in the 35 to 40 range. I had the adjustable one set at 45 PSI or somewhere in that neighborhood. The Bosch EFI basically reconfigured itself to handle the increase in fuel PSI. We found that the engine pulled stronger, didn't run any hotter than normal, passed smogged but we lost a couple of MPG but not a lot.
Robert K. Kuhn
CRX Owners Group President (http://www.crx.org/southcal)
1990 Honda CRXsi (http://www.hooligan.cc)
ICQ # 3714283 (nickname: godzilla)
