kmo25

iTrader: (1)

The other day I had an issue with a hot restart in which my car would crank but not fire. In trying to eliminate any possible cause I reinstalled the PRC solenoid. Up to this point i had been running a vaccum line directly from the intake manifold to the fuel rail. A previous thread on this forum talks about what this solenoid is/does

from M.net

The '96/7 PRC solenoid is intended to prevent fuel in the rail from boiling by keeping the pressure high in a hot restart situation. The solenoid admits atmospheric pressure to the FPR, instead of manifold vacuum, for long enough to get overheated fuel back to the tank. During this time the ECU leans the mixture a few percent to allow for the increased pressure difference across the injectors. And below is what it looks like.


When i went to datalog today I noticed that my car was running much leaner under boost. I had to add around 10% more fuel to get the AFR back to where it was before. Under normal cruise there was no difference. I'm not sure if this is well known, but I wanted to throw it out there for those that decide to either remove this solenoid or add it back on. It seems like it will have a noticeable impact on your fuel tables. To confirm I disconnected and reconnected this solenoid and it was defiantly having an effect on my boosted AFR.

I'm guessing it has to do with a difference in pressure within the rail but I was under the impression that was only during hot starts not during sustained driving.