Passenger side running lean in PE

[NJ_Phil]

First drive of the season after a few over the winter upgrades shows passenger AFR running a full point leaner than the driver's side.
Both STFT and LTFT run the same and both WBs track evenly in CL and only runs lean during PE.

Running a 58psi return system with a AEM-380 secondary pump which I can see kick on at 3psi of boost, about 780hp.
Stock fuel rail with crossover tube, fed from the stock pass side.

Suspected the passenger side rail might be getting starved for fuel but second guessing that because the variation shows immediately when dropping into PE even with injectors running only at 20% DC. Going to pull the plugs tomorrow for a look.

Looking for some advice.

Thanks

[VodeAn]

Are you suggesting you make 780hp at 3psi ?

Swap the widebands between banks and see if the issue follows.

If not, then swap the injectors and see if the issue follows.

You may also be getting air in the fuel when the second pump kicks on, sometimes when that happens the air bubbles will end up on one side of the rail and not the other.

[NJ_Phil]

Are you suggesting you make 780hp at 3psi ?

Swap the widebands between banks and see if the issue follows.

If not, then swap the injectors and see if the issue follows.

You may also be getting air in the fuel when the second pump kicks on, sometimes when that happens the air bubbles will end up on one side of the rail and not the other.

780@14psi. Boost bled off till I figure out what's going on
Swapped sensors and waiting for better weather to try it out, Plugs all burning even.
I'll run the pump on manual to rule out air.

I had to weld on a second bung to pipes which is 1/2" taller than the other one and might trim it back.

Thanks

[GHuggins]

What type of changes were made over the winter? Are running modified cylinder to cylinder fueling? Are you running a modified in any way torque model?

[NJ_Phil]

What type of changes were made over the winter? Are running modified cylinder to cylinder fueling? Are you running a modified in any way torque model?

All changes over the winter were unrelated to fueling/AFR. Solid motor & trans mount, blower drive, etc... in addition to adding a second WB sensor.
No mods to individual cylinder fueling.

Wondering if the new bung I welded in being 1/2" taller than the other one is the reason. Going to trim it back

[NJ_Phil]

So it turns out the leaner setting switched to the other bank after swapping the sensors so it's either the gauge or the sensor. Thinking about swapping sensor connections at the back of the gauge to see if it's the sensor or the gauge itself. Both gauges are AEM-0300 and both sensors are Bosch LSU4.9. Bought the 2nd WB setup 2 years ago and the new one just seems sluggish to respond and shows a whole lot leaner than the older one. Was going to buy 2 new sensors but they are $116 each so wondering if there is a way to test them outside of the car.

AFR difference is even larger under some conditions. A short stab shows WB1 running 11.3 and WB2 running 13.0 which is insane.
wb_error.png

[NJ_Phil]

Problem solved. I thought the new sensor was bad and reading lean but it turns out my original sensor was bad and reading rich. Both banks are line on line now.
Bad part is I've been running AFRs in the low 13s when WB showed 11.4. Good news is it will take more * after I redial in the VE.

New_WB.png

[VodeAn]

Glad I could help, a sensor is cheaper than a motor!

[sevinn]

Can you tell me what sensor you purchased? I'd like to have a spare sitting around for my couple of aem WBs I have now.

[NJ_Phil]

Can you tell me what sensor you purchased? I'd like to have a spare sitting around for my couple of aem WBs I have now.

Hey Sevin,
It's AEM PN 30-2004. Looks like their 30-0334 gauge calls for 35-2003 but I run the 30-0333 gauge. Not sure what the differences are or which gauge you have, or if it matters

https://www.summitracing.com/parts/avm-30-2004

Phil

EDIT:
PS The new sensor from Summit had the exact same part numbers engraved on the connector as my old one.

[dr.mike]

The sensors do drift with age/use. If you have an old one and a new one, try doing a free-air calibration on both.

[NJ_Phil]

The sensors do drift with age/use. If you have an old one and a new one, try doing a free-air calibration on both.

The sensor was off almost 2 full points, reading 13.0 when it was really 11.2 so it failed, not drift. I was running it for about a year. It never passed a free air calibration while installed in the pipe which from what I understand is normal and didn't pass even after I pulled it out. Now both new sensors will pass calibration installed in the pipe if I let the car sit overnight.

I did add in 4oz of ZDP additive when I did the cam, lifters and rocker bushings and occasionally run "RaceGas" additive which coats everything orange so maybe that messed it up. Just happy I didn't tune it leaner cause I would have been making passes at 14psi, close to stoich.

[dr.mike]

If a sensor will not pass a free-air calibration ( out of the pipe ), it has almost certainly been damaged. Usually from thermal shock. But, sometimes, from lead or silicone poisoning. I keep running into people who think that it's a good idea to warm up the sensor, before starting the car. This practice is like playing Russian roulette with the sensor's ceramic element.

I wouldn't 100% trust a free-air cal, done in the pipe. Even after left overnight. In fact, it is ideal to have a fan blowing on the sensor while the calibration runs.

[dr.mike]

I think I should do some experiments with the race-gas additive. They say it does not damage o2 sensors. But, I'm pretty sure that only goes for narrow-band sensors. Any kind of coating, like that, is going to interfere with the operation of the wideband's pump cell. And the result would have it reading over-rich, when on the rich side of 14.7

[dr.mike]

Verified. Running the RaceGas additive does cause the sensors to lose sensitivity. i.e. they have to work progressively harder to get to the zero oxygen point. Which, makes them read richer than actual on the rich side. And, leaner than actual on the lean side. For a while, you can compensate with free-air calibrations. But, eventually, the sensors are so plugged up that they can't even calibrate. ( I didn't get that far ). If you are going to run this stuff, I suggest doing frequent free-air calibrations. I would NOT trust readings from anything but a brand new sensor on a WB without free-air calibration.