Pat

Did some comparison logging between the two FPRs today with Rusty's help. With the crushed 4 bar regulator at 3000 RPM my O2 voltage was .840. With the true Bosch Motorsports regulator in the same scenario it was .860. There IS a difference.
Also, boost at 6200 RPM was 7 psi with the crushed FPR, while with the motorsports regulator it was 10 psi at the same engine speed.
Between 5K and 6K I was getting more fuel in there with the motorsports FPR as evidenced by avg O2 voltage of .875 vs .865.

1heartaudiworld

If you have a real bosch 5 bar the best thing to do would be to test the actual pressure of the 5 bar and then crush the 4 bar to that level.

Pat

AWE sold it as a crushed 5 bar. I did not measure it myself.

1heartaudiworld

I worked there years ago (01-03) and we had a great rig for checking the pressure of them while they were being crushed.

What year is your car. Obviously it has a narrow band and that being said the voltages while they do change are pretty much useless to use even for comparison sakes.

I also don't fully understand the change in boost. If you have an AEB boost will be determined based on intake temps and mass air flow. If you have a later car boost is determined by the torque request so it would change.

That being said with more boost the car is going to increase the injector duty cycle on either an early or late motor, that would certainly result in different 02 sensor readings on a narrow band as they are highly inacurate.

On a car with a narrow band after about 4k its going to start to run open loop and not use the 02 sensor for really anything at all. The later cars with widebands stay in closed loop the whole time and try to hit their target AF.

The better test would have been to set boost with a manual boost controller, check AF with a wideband and also check injector duty cycle.

Pat

Good info! Not sure what to tell you other than it's a 99.5, so it has an AEB.

ModifiedA4

also, the long term FTs might show some differences too.

Pat

(from Rusty):

You're correct about the narrowband O2, to a point. They are lousy to measure absolute A/F ratio, but the sensors themselves are pretty self-consistent, so a .01 volt difference in the "tuning" range (~.865) is notable.

Injector duty cycle is pegged at 16.32 msec, the limit for amerispec AEB engines.

Pat's MTM chip goes open loop just off idle. Yes, it really does, I've watched it using block 099.

Yes, the better test would have been to set boost with an MBC. One does what one has time to do... *sigh*

These results aren't conclusive, just an indicator. FWIW we did two runs, the first run was too rich (.890) and he had 2 lbs *less* boost @6000. I've logged a fair amount of data with his car, and I've *never* seen .89's, so I think it's reasonable to say he's getting a bit more fuel.

shawfm

it makes me feel a lot better about spending the extra money on the 5 bar FPR.

Pat

Fuel trims are +2.3/0.0