Guys, heads up to anyone with a defective valve body (06-07). My lockup condition has worsened to the point that it's somehow negatively affecting my AFR. When I'm cruising, as long as the car is under partial throttle (could be as little as 5%), everything is fine, but the second I let off the gas and the tranny locks up, my AFR goes crazy, shooting up to 21 (see pic).
[normal AFR at 40 MPH cruise with partial throttle, lean condition seconds later when I let off the gas].

Just started up the beast and a cloud of white smoke came out the exhaust! The good news is that I have an appointment with Infiniti on Monday, and there's a good chance they'll replace my valve body. Bad news is that God only knows what this has done to the motor.

The whole mechanism behind this is a mystery to me, I wonder if there's some kind of protection built into the ECU, if it detects severe lockup, it cuts fuel? I can't think of anything else that explains it.

EDIT: and I'm 100% sure it's related to the transmission, because it instantaneously starts when the lockup occurs, and instantaneously stops when the lockup is resolved and it downshifts (AFRs return to normal).

 

On my engine (NA) I have seen it hit 30 AFR after you let off the gas which is normal. Not sure in your situation though, would suspect it would be similar.

 

Same here as you let off the pedal the engine runs very lean as it dosent require any fuel which is normal.

 

Normal for you guys to exceed 20? I just can't explain how it perfectly follows the lockup, it's a clear pattern, let off throttle, jolt, AFR->21, vibrations, more vibrations, downshift, AFR->14.7. Of course I am paranoid, I'm the defect man.

P.S. I don't know if I described it well enough, but I'm not talking about gunning it and letting off the throttle, I'm talking about 3-5% throttle (barely pushing the pedal) to cruise. RPMs don't even really change, that's what's so weird about it.

 

I doubt your AFR's have anything to do with the tranny, mine shoot up super high every time I take my foot off the gas. Whether it's 5% throttle or 100%, it will do it.

 

I also forgot to mention that it doesn't happen within the first 10 minutes of driving, while line pressure is still increased and the trans is cool. If I let off then, AFR stays at 14.7 and it downshifts properly.

There's one way to know for sure, if Infiniti replaces the VB (fingers crossed), and it mysteriously disappears, it's probably to safe to say it was definitely the VB.

 

When you let off the throttle, the injectors turn off and the engine turns into an air pump. AFR goes to infinity.

 

The reason it doesn't do it cold (AFR), the ECU is still in
warm up mode and delivers more fuel. It is normal for
no AFR or lean on decel, as the above post states, the injectors
shut off at that point. Get back on gas pedal and they start
again. My 350Z is the same way. Go down a hill, no throttle
and the injectors will shut off.

 

Jesus, you guys are engine geniuses. So basically I'm just witnessing a wide variety of engine states.

Regarding the VB, Infiniti has the car, the head mechanic at my dealership drove it home and witnessed the lockup repeatedly, they proposed a solution, but I don't know how I feel about it. They ordered a new VB, they're gonna put it in, and if the lockup mysteriously disappears, problem fixed, free of charge. But my service manager mentioned something weird, said that the head mechanic thought it could be the VB or possibly the MAF!? That the SC may be confusing the MAF and that's what's causing the lockup and violent shaking. Yeahhhhhhh. Nevermind that this all started when the car was bone stock and I had a shiny new, clean MAF sensor. We'll see how it goes, just sucks not knowing if they're really putting in a new VB and test driving it.

 

+1....most of the gauges lean out max at 20'ish, so that is completely normal on decel.

 

There is a TSB for this issue.

 

Oh I know, I'm the one who found it (with another member).

They called me yesterday and said they replaced it, I'm shocked and appalled. Gonna get it upgraded ASAP. Have to take it out for a few days though and make sure the lockup is gone.

 

Wow, your dealer worked on your car boosted? I'm too scurred to go to a dealer for anything!

 

They were pretty reasonable, but I approached it very carefully. I had a copy of the TSB, I explained that the lockup had been happening for over a year, even when the car was stock. I also told them the lockup didn't make any sense as a symptom of damage (from the SC), something like shift flare would be a symptom of damage. And I also told them straight up that if the clutch packs were shredded, or the motor blew, I'd take full responsibility.

Looks like it worked, let's hope it doesn't turn into a nightmare, with my luck when I go to get the new VB upgraded we'll find out the old one is still in there.

 

yeah good luck on that, but man you still got lucky they decide to work on your car, some stealerships are just b*tchass fooz...update us when done