Lean @ WOT

[iceorphen]

This just started happening recently after installing rebuilt TB and reflashing my chrome to fix my fuel trims.

If I ease into the throttle ill have no problems, accelerates fine all the way to WOT.

If I floor it from 1.5k it will run lean.. around cruising afr, went as high as 16 the first time it happened.. havent floored it since.

If I rev at idle, near redline i get ~2 counts of knock.

Im thinking fuel delivery issue, pump is wally 400 hotwired, 43psi at idle. boosting @ 12.5psi

any ideas?
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[futurevr4man]

there are a few of us that have this lean spike issue if you floor it. my car does the same thing. i am currently trying to figure out why

[HLxDrummer]

What happens if you floor it from say 3K (don't blow up anything doing this!)? How much knock did you get during that WOT pull?

Did you have it tuned before you reflashed? Maybe you fixed a boost leak you had tuned out now it is way lean? Did you try running the stock tune?

[iceorphen]

What happens if you floor it from say 3K (don't blow up anything doing this!)? How much knock did you get during that WOT pull?

Did you have it tuned before you reflashed? Maybe you fixed a boost leak you had tuned out now it is way lean? Did you try running the stock tune?

If I floor it from 3k, occasionally it will be fine and haul ass, sometimes it will run lean. Highest knock I encountered was 11, but mostly stayed at 5.

I've kept stock tune with minor adjustments while breaking in new motor, so when it does actually drive nice at wot, its usually rich ~10.0

[HLxDrummer]

So it is intermittent.. Any chance you can borrow an electronic fuel pressure gauge from someone? Then you can make sure fuel pressure rises appropriately with boost (and consistently). That will rule out fuel lines/pump/regulator/filter. If that stuff isn't the problem then probably electrical (sensor/ecu/injectors) I would guess.

I'm guessing no knock when it is running 10.0:1? (Just want to rule out wideband problems).

[iceorphen]

So it is intermittent.. Any chance you can borrow an electronic fuel pressure gauge from someone? Then you can make sure fuel pressure rises appropriately with boost (and consistently). That will rule out fuel lines/pump/regulator/filter. If that stuff isn't the problem then probably electrical (sensor/ecu/injectors) I would guess.

I'm guessing no knock when it is running 10.0:1? (Just want to rule out wideband problems).

No electric gauge on hand , and no knock when at 10:1.

Since the reflash my low trim has been ~87, I'm going to try adjusting the VE in chrome again and see what happens..but I dont think it has that much of an affect if any at WOT

[HLxDrummer]

Seems to me like a mechanical/electrical problem since it is intermittant. Any chance there is a vacuum leak or something?

[iceorphen]

Leak tested about 2 weeks ago prior to this happening, ill be doing another this thursday hopefully.

[Greg E]

Spark blow out/foul out.

[iceorphen]

even at .28 and 12.5 psi O_o? Plugs were changed a month ago.