application is: 99 civic si, JRSC@9psi, JR BTC, JR MAP, JR VPAC

the hondata and conversion harness was stolen along with my $700 alpine stereo when my car got stolen. that is a different story.

i put back in the JR FMU, stock injectors, and jr bandaids for the meantime.

Car is seriously bogging at WOT. slight backfire at WOT sometimes with black smoke. Fuel pressure guage under the hood reads 70 psi for both static and idle. Giving some throttle, the needle barely twitches. Is the JR FMU jacked up.

Also theres a CEL for primary o2 sensor and the AF gauge stays red and doesnt show most of the time. I can relate the O2 sensor to the AF guage which causes bogging. Also, im assuming the 70psi is causing the bogging also.

Spark plugs gapped at .038. spark plugs are black with with alot of carbon residue. Also theres a brownish red residue that looks like either oil or excess unburned fuel burning outside the electrodes.

My main question here is.:

Would the P2T being in default open loop mode due to the primary O2 CEL being thrown be enough to cause the JR FMU to put 70 psi of fuel pressure at static and idle? If not so, then, the only thing I can think of is a malfunctioning FMU.

I didnt want to mess with the initial settings on the FMU that I had adjusted before for when it begins to rise, because, the static was at 60psi and idle was at 47 psi, before the hondata was put in, which was pretty well off for the setup before @ 9psi. Ive already ordered a new o2 sensor to solve the cel problem and to see if taking it out of the P2Ts default open loop mode will cause the fuel pressure to drop. If its not due to the o2 sensor, then, if it is the FMU, I have to use this setup for the time being. I just dont have the money for the new hondata and conversion harness yet.

If its not the FMU, then, im going to change out the spark plugs, wire, cap, and rotor. If its not that, then, im going to give the TPS and injectors a look.

Any thoughts or solutions?

 

well you certainly have to straighten out that fuel pressure problem but the computer has no control over that. The FMU is either screwed or one of the vacum lines is blocked or kinked causing the FMU to think it's in a WOT setting. Throwing that much fuel into the car will kill the cat and certainly trip a CEL and cause backfiring and every other problem you're having.

 

is the default open loop mode suppose to run rich? enough to put 70psi at static and idle?

 

When the car runs in open loop, it ignores the signal input from the O2 sensor. However when the car runs in "limp mode" with a CEL on, the ECM will default back to a "safe mode" where it tends to run on the rich side. It does this by simply increasing the pulse width of the injectors, which allows more fuel into the cylinders. So as you can see, the high fuel pressure problems you're having are totally unrelated to anything the computer is doing. It's an FMU problem you have from either being a faulty unit or a plugged, kinked or disconnected vacum line going to the FMU causing it to think it's at WOT (wide open throttle) and stepping up the fuel pressure to a constant 70 psi at idle.

 

UPDATE
swapped out the primary o2 sensor with a denso. car runs smoother now, no more studdering at lower rpms. still bogs at WOT.