Possible Lean Issue at WOT

[TheGreatGSX]

I've been trying to figure this issue out, and I realize several people on here have opinions about the narrow band A/F gauges but hear me out please.

After my recent install (Check profile) my A/F gauge has been reading lean under WOT. I understand narrowbands aren't accurate and in this case I do not need it to be accurate since I am not tuning, the point is, the gauge is reading differently than what it was under WOT.

When I purchased the car, it already had the narrowband in there. With the complete stock setup, the gauge worked correctly (Although not accurately), it would oscillate during idle, be rich during WOT, then be lean during coast.

The gauge is still working properly, all except WOT where it goes straight to lean as soon as boost starts to build. The weird thing is, I'm not getting knock at all, so I'm kind of confused as to what would cause this. If anyone could point me in the right direction and please refrain from simply saying "Get a wideband" I would greatly appreciate it.

 

[thirsty]

G'day.
I had a lean out issue that melted a piston at 180kph during a rally.
510cc injectors, but one was only opening 70% at WOT.
Maybe get the injectors flow tested by a shop with a racing pedigree.
Cheers
Ross

 

[SteGerHPI]

I don't know what your recent install was but check everything having to do with that.

Next suggestion is to log it, and check your actual 02 voltage rather than the disco light's led. Check your MAF signal, timing, and fuel trims and see if the car is acting like it's running lean, and then do a BLT.

I'm going to mention it anyways. GET A WIDEBAND!!!!! Especially with your mod list.

 

[TheGreatGSX]

I don't know what your recent install was but check everything having to do with that.

Next suggestion is to log it, and check your actual 02 voltage rather than the disco light's led. Check your MAF signal, timing, and fuel trims and see if the car is acting like it's running lean, and then do a BLT.

I'm going to mention it anyways. GET A WIDEBAND!!!!! Especially with your mod list.

Recent install is in profile, basically s16g turbo, 750cc FIC, 190 Walbro, SS O2 housing. I should of also mentioned I have logged with EvoScan. EvoScan logs low O2 volts during WOT and is pretty consistent with the A/F gauge. The fuel trims are:

Low = 12.5%
Mid = -5%
High = -5%

Which to me doesn't make sense, because from what I understand wouldn't the ECU be adding fuel during high fuel trim rather than subtracting fuel (If it was indeed running lean)?

The car doesn't seem to be acting like it's running lean, and no knock at all. As I've been told (Not sure if it's true), if the car was truly running lean, you'd get knock.

Also, I thought a boost leak would cause the O2 volts to read high? Thanks for the help/advice.

 

[SteGerHPI]

It sounds like you may have a bad MAF. Generally anytime fuel trims go opposite directions like that it's a sign of a bad MAF. It's dumping a poop load of fuel down low which is a sign of a vacuum leak or a bad MAF signal. If anything your trims should be going the opposite direction, pulling @ idle adding w/ load. I would try a friends MAF, do a battery reset, and drive it around for an hour or so. Your car will probably stall and do some weird things for a while while it's resetting adaptations.

 

[DSMopar]

What are you tuning with? Fuel corrections are only for part throttle...