A/R seem to have flipped? Any thoughts...?

[s14unimog]

I'm in the middle of breaking in my new engine and have noticed something alarming. I've gotten about 300miles on it, running from the previous tune. What I mean by that, is that I have a Nistune system that was previously tuned on this exact setup, minus the fact I came from a 28RS to a 20G and went to a slightly larger head gasket. Either the case, I'm not boosting and I'm just using it to rack up some break in miles (0 boost thus far).Either way that car is a little rich but not horrible. What happened was out of nowhere, it seems. I was cruising down the road under decel when I happen to look at the wideband; 10.1......9.9....10.8....(not what it should be saying). Previously we were a constant 21:1 under decel; meaning the wideband maxed out lean. Not only has that happened, it seems, at idle, as it lopes, the air fuels lean out a bit more than normal. I've already ordered a wideband sensor, I was worried it was close to fouling anyways; that's installed and was not the problem. Does this sound like an injector leak or possibly a faulty FPR (mines a Nismo adjustable, manufacture defects?)

Any thoughts would help

[Sileighty_85]

Ive heard alot of complaints on the Nismo FRP kinda a hit and miss FPR

I have a Sard FRP on mine and it works great NP.

For your WB to show lean on Decel (Engine Brakeing) that normal cuz durring engine brakeing Inj Duty cycle is reduced to 0.0%

[s14unimog]

I know, that is why I'm worried. Its been going super rich; 10's and 9's on decel. I looked into Nismo FPR experiences and I've noticed a few have complained about the "hat" spinning. I just checked mine and noticed the same thing; that it spins. It must be leaking too... When I'm under decel, how would the injectors let fuel in though? could the lack of vacuum increase the fuel pressure enough to leak past the o-rings?

[Sileighty_85]

Oh i see what your saying.

Hmm that is a bit strange, I would look into replaceing the O-Rings.

But how are the AFR's under normal driving? I would ask what they are under boost but your durring the break in.

What injectors are they? Could be leaking?

[s14unimog]

They are Nismo 740's. I have the car stored at my work. I just ran out there an did a very clean JB weld job on the FPR, lol. IT should be enough to stop the air leak. I've also clamped off all my vacuum lines. If this doesn't solve the problem, I'll pull the injectors and replace the rings. I would HOPE my injectors aren't leaking but I guess it could be anything attributed to fuel.

[s14unimog]

I checked on my FPR fix today, it seems to have cured the spinning problem as well as seal the cap closed. I went to autozone with hopes of finding a small in-line fuel pressure gauge. To my surprise, they actually had a fuel pressure service kit that I could rent. I hooked up the gauge and noticed I had about 42~ psi at idle and the FPR is responding to vacuum correctly. (less vacuum=more pressure and more vacuum=less pressure)

I'm starting to worry that this is attributed to my tune. Have any of you ever seen weird changes from un-hooking you battery? That's the last thing I've done that could have come close to affected the ECU or tune.

[s14unimog]

I figured out the issue and it was NOT related to the Nistune system at all. the problem was due to the TPS's base voltage had bumped over 0.45V at closed throttle. I've since then changed the base voltage to 0.40V and it has cured the issue.