Nitrous tuning questions car going rich on the big end

[NOS JOHN]

Im Just trying to figure out why my car goes rich AF in top of 2nd and 3rd.
Here is my set up
408 direct port nitrous kit w/dedicated fuel cell.
T400
speed density tune
O2s turned off.
Car na runs a 12.3 af flat accross the board. On nitrous the af goes off the trans break up to a 12.1 then down to 11.7 through 1st then when I hit 2nd it goes back up to 12.1 then back to 11.7 then starts going down to 10.5 top of 2nd and all of 3rd.
I have the dedicated fuel pressure at 8 psi. I just cant figure it out unless the computer is commanding more fuel out of my injectors in 2nd and 3rd.
Im new to this but the car is tunned by a well know guy here in the midwest.

[Google]

Im Just trying to figure out why my car goes rich AF in top of 2nd and 3rd.
Here is my set up
408 direct port nitrous kit w/dedicated fuel cell.
T400
speed density tune
O2s turned off.
Car na runs a 12.3 af flat accross the board. On nitrous the af goes off the trans break up to a 12.1 then down to 11.7 through 1st then when I hit 2nd it goes back up to 12.1 then back to 11.7 then starts going down to 10.5 top of 2nd and all of 3rd.
I have the dedicated fuel pressure at 8 psi. I just cant figure it out unless the computer is commanding more fuel out of my injectors in 2nd and 3rd.
Im new to this but the car is tunned by a well know guy here in the midwest.

I would have the well known tuner look at it. hard to say with no tune or log to look at. could be a few diff things from the tune or could even be the plugs.

[NOS JOHN]

Running #9 NGK non proj. plugs. Here is the graph of the log. I have a 98 comp. with a 1 bar going to have it retuned with a 2 bar.

[Higgs Boson]

I am running SD nitrous as well on a 408 but mine is a plate kit (200 shot).

I have trouble with a cell or two after the hit getting rich then it goes back to normal....the car has a quick bog at 4000 or so when it happens and picks back up. I can't figure it out either.

With yours, what does the timing map look like? Does it decrease as the RPMs go up?

[Higgs Boson]

When I say timing map, I mean the hi octane spark table from 3200 and up and higher than .8 g/cyl

[Frost]

What is the bottle pressure doing during the run? Is the up/down fueling regulator bounce on the nitrous fuel side?

That idle swing before the run is from having the TPS reporting >0.4% If you get it back to 0%, it should settle out.

[NOS JOHN]

The bottle pressure is at 950 at the start of the run then goes down to just 900 im running to 15lb bottles Y together. I dont know about the fueling regulator bounce on the nitrous fuel side.Frost You mean it only acts up when its on spray.

I know the idle was great until I put colded plugs in then it idled like crap.

[LSxpwrdZ]

Widebands don't read right with nitrous! Mine read's 10.8afr on the bottle and the plugs tell the complete opposite. My timeslip's don't lie either.

[AJxtcman]

Cot?

[jpracing01]

Might want to check the siphon tube on the bottle... What brand on bottle is it?

[AJxtcman]

This is either Cat Over Temp or Piston Protection. This is a wide-band log. The PCM is commanding the AFR to 10.3 and the wide-band matches.

[Smitty]

Since it doesn't do this when your not spraying the car, (and your getting your additional fuel from a source other than the computer) I would look at your n20 kit first.

Sometimes fuel pressure gauges can be off especially when it comes to direct port kits, have you had the kit flowed?

Take a look at the duty cycle of the injector on a hp pass log vs nitrous pass log. I know that mine (wet kit) are within 1% at various data points (RPM) throughout each pass. (compare similar rpm points, other points such a shift recovery will be off due to the difference in rpm from the nitrous)