vristang.... question about your post on stangnet

[Cougar5.0]

I don't know where this rumor got started that the low slope is "feathered in" using the breakpoint "flow" info below 2 ms PW (A9L), but I have to wonder when exactly it is cut in. I recently changed mine from 46.8 to 42.6 & back without really noticing much of a difference - just some light popping in the exhaust on decel when it was lowered to 42.6.

[Italian LX]

Originally Posted by vristang

EDIT; Qwksnke - Are you using a Tweecer with your x3z?

[vristang]

I have not heard the "feathered in" part before.

Here is what I have written on the A9* use of Injector Breakpoint.
This is from stangnet as well. http://forums.stangnet.com/showthread.php?t=640613

4. The A9L strtategy uses the Function - Injector BreakPoint a little differently than other strategies. For most strategies the Inj PB is the point at which the computer switches between the Injector High Slope and Injector Low Slope, which makes sense.
The A9L however is slightly different in that the Injector BP is actually used as an Injector PulseWidth modifier, and the Injector BP is hard wired into the EEC as 2ms. When you make a change to the Function Inj BP you are actually changing how much fuel is cut from the Inj PW below 1,500rpm. The use of a larger number in the Inj PB Function will pull more fuel from the already calculated PulseWidth, until 1,500rpm.

To the best of my knowledge this is correct.
Let me know if clarification is needed.

jason

[Dale McPeters]

'91lx stock fp reg. with 100,000 mi and a 255lp/hr pump =

[vristang]

Originally Posted by Dale McPeters

'91lx stock fp reg. with 100,000 mi and a 255lp/hr pump =

I don't get it?

[93Cobra#2771]

IIRC, the slopes were set the same on the Cobras and the breakpoint was indeed used as described.

Roush actually did the tuning/programming for the 93 Cobra. They had a limited amount of time to get the tune right - in fact, they only had one shot at the tune to get the car to pass emissions, or the car would have been delayed.

Don't know if that was the case on the 95 Cobra.

The deal with bigger fuel pumps is a pretty new one - I heard it a couple weeks ago on the corral, I believe. I have a feeling it is a trickle down deal from the late model returnless fuel systems - course that is a guess on my part.

What Dale's saying is his is just fine, with no problem regulating his 255lph pump.

[Dale McPeters]

Originally Posted by 93Cobra#2771

What Dale's saying is his is just fine, with no problem regulating his 255lph pump.

That would be correct.....

[vristang]

I recently returned to the stock fuel regulator as well. I didn't seem to have any trouble with fuel pressure and the 255lph pump.
I didn't get to test it very long though, as the motor has now died.

I am starting to think that some returnless fuel system info has worked its way into A9* tuning.



Off Topic -
Since there seems to be a few Cobra tuners here...
Has anyone else had issues with Decel Fuel ShutOff. The car was continuing to run lean several seconds after a shift.
I had to fumble my way through this as I couldn't find any info.
Just curious if other X3Z users have had a similar experience?

jason

[93Cobra#2771]

Decel fuel shutoff is actually disabled on A9* family of processors. And I don't think that would be causing your issue. You need to up your fuel tip-in, methinks...

[Cougar5.0]

Originally Posted by vristang

I have not heard the "feathered in" part before.

Here is what I have written on the A9* use of Injector Breakpoint.
This is from stangnet as well. http://forums.stangnet.com/showthread.php?t=640613

4. The A9L strtategy uses the Function - Injector BreakPoint a little differently than other strategies. For most strategies the Inj PB is the point at which the computer switches between the Injector High Slope and Injector Low Slope, which makes sense.
The A9L however is slightly different in that the Injector BP is actually used as an Injector PulseWidth modifier, and the Injector BP is hard wired into the EEC as 2ms. When you make a change to the Function Inj BP you are actually changing how much fuel is cut from the Inj PW below 1,500rpm. The use of a larger number in the Inj PB Function will pull more fuel from the already calculated PulseWidth, until 1,500rpm.

To the best of my knowledge this is correct.
Let me know if clarification is needed.

jason

Feathered in means that there is a smooth transition between lo & high slopes - which is true.

I can't verify the statement above, but it does not seem to jibe with what I am understanding after reading up. I will post an explanation & hopefully a graph to help explain the breakpoint stuff as soon as I can figure out how to translate it into words.