Ronny

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Installed aa new 396 SB this past summer. Running EBL
Set BPC to 174 for 24 lbs injectors at 43 lbs FP. I realize I need stronger fuel pump and larger injectors that is coming soon
Broke in engine ran well but rich. Used race gas due to new tune and 11/1 compression. ran a datalog and it verified rich as did plugs.
Found I had no vac to speak of at 10in/hg.
Rich was due to the VE table moving to higher MAP at cruise speeds..
Replaced plugs. Added a vac pump and vac returned as well as brakes.
Car ran surprisingly well on tune.
WB showed lean???
Each successive log showed rich by 5%-9%. Corrected table pulling fuel. Did that about 5 times removing fuel 5-7%.
I suspected the WB sensor as kaput due to lead(??) in gas. Innovate confirmed. Replaced WB sensor after the leaded gas was used up. Situation improved immediately but then reappeared after several cruises but intermittent in that it showed on WB14.3 then a minute later lean 16.0/1
Running off NB in one bank WB in other. Could the NB also be kaput?
PE and AE is good as far as seat of pants so that seems to enrich properly.
Highway mode is turned off as is de-accel enleanment.
I am thinking a ext leak at NB side of headers but no evidence of that noise. Or the NB is shot. NB is switching as expected and the cycles look normal.
What do you think?

Dr.E

Slow process of elimination: Did you change the lead contaminated oil as well before you replaced the O2 sensor? Check for intake leaks? (new motor slipped gasket during assembly) What type of cam solid or hyd.? ( valve adjustment too tight on a valve causing slight leak? )Is the 10in/Hg what you expect from the cam specs? very radical cams cams cause a false lean at idle that the o2 reports to the ECU even though you are reducing fuel in the calibration the ECU is acting on data that is reporting lean condition. Do the logs show rich at all RPM? Worse at idle better at cruise?
Just brain storming....

Ronny

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Hydraulic roller. The cam is 234 intake and 242 ext.@ .05. LSA is 112. lift is .628 int and .611 ext. This is a street driven engine. Cam was picked out by Comp Cams tech line rather than me going to bottom of choices in catalog. Ext system is 3.0 inch with a X crossover. NB is right after the connection form collector to pipe on drivers side and WB is about 20 inch further back do to fitment on pass side.. NB is heated as is WB. Intake is a single plane Vic J. WB data is inputted to datalog. I will post a datalog (Whats.Up/EBL-ECU.).

Engine was built on a stand by professional engine builder. He has done prob over 100 builds. Works at a shop that does high end work. Known him for 30 years and sent to him a lot of customers due to my business relationship. So unlikely an intake leak or valve.

Changed oil after the issues at end of season but still has issue with fresh oil.

Vac pump serves the brake booster only so I expect the 10-11 HG is still present at intake.

What puzzles me is how can the WB report lean and the NB report rich? Now that is intermittent. It seems the WB reads get better after manifold is heat soaked. That is moves from 16.0/1 to closer to 14.3/1. Maybe fuel not completely atomized and shows lean? But that should appear at NB as well?

Thank you.

Dr.E

A silicone poisoned NB will report rich. ( new engine build lots of possible silicone contamination points)
You could also swap WB and NB locations as a comparison to see if the readings change?
More food for thought. These days my brainstorms are more like gentle spring showers!

Ronny

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see attachment: datalog

Ronny

iTrader: (1)

I am a bit surprised that Innovate WB sensor would be corrupted by race fuel(lead). Maybe it is designed to use passenger car WB that is E10-E85. Now I see on market a specific devise that will monitor E85 to account for varying amounts of alcohol in the gas. So E85 could actually have more or less than 85% alcohol%.

Ronny

iTrader: (1)

Just spoke to Innovate. They say odds are good the NB sensor is kaput. I asked how serious racers can monitor A/F with race gas. they say they replace them every other run ! OK thanks to DR. It could be silicone as well I cant devalue that. My NB is ten years old so that is OK. Car goes in soon for fuel pump and injectors so timely. Once in with new stuff I can ring it out.