Scott 88 GTA

OK, I'm playing around with the ARAP bin in my car, and I need to know what exactly the following things mean:

DFCO Enable RPM Threshold: When the rpms are decreasing the fuel will be cut off at this speed, correct?

DFCO Disable RPN Threshold: When the rpms reach this setting fuel resumes.

DFCO Enable Load Threshold: When the load (LV8) decreases below this DFCO can be enabled.

DFCO Disable Load Threshold: When the load increases past this DFCO is disabled.

Maximum RPM Decrease to stay in DFCO: ? I don't understand this one, especially since the units on it are RPM/12.5, and it's set to 88 in the ARAP bin.

DFCO Enable TPS Threshold: When the TPS drops below this DFCO can be enabled.

DFCO Disable VSS Threshold: When the vehicle ________ (speeds up or slows down ?) past this DFCO is disabled.

Decel Enlean Enable Diff TPS Threshold: ?

Decel Enlean Enable Diff Load Threshold: ?

Decel Enlean BPW Factor (Low DRP's): ? What's a DRP?

Decel Enlean BPW Factor (High DRP's): ?

Can someone please clarify for me what these things mean? Thanks.

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Black 88 GTA L98
261 RWHP, 345 RWTQ
13.406 @ 103.72 MPH
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back, Stock PROM
E.T.F.A Member #11

[This message has been edited by Scott 88 GTA (edited March 18, 2001).]

GregWestphal

iTrader: (1)

DFCO is enabled (fuel can be cut off) above this engine speed.

Correct.

Yep.

Right on the money.

As long as the RPM decrease doesn't exceed 88 rpm in 12.5 msec, then is remains enabled. This equals 704 rpm in 1/10 of a second or 7040 rpm in 1 second, so I don't know how often that goes into effect.

Right again!

Slows down below this speed.

I'm not sure about these, although I don't think they're enabled in the ARAP bin...

[This message has been edited by GregWestphal (edited March 19, 2001).]

F22Raptor

Damn, I better print this out!
Why isn't there any DFCO with WinBin?

Scott 88 GTA

Thanks Greg. But are you sure on the first one? The reason I ask is because I've noticed that when I'm braking when the RPM's drop to 1200 the car suddenly starts braking harder, as if the torque converter just unlocked or something. I thought that it was the ECM cutting fuel off at that speed so that the engine was no longer putting power out and the relative force of the braking just increased. Just observations I've made.

Does anyone know what the Decel Enlean variables do?

GregWestphal

iTrader: (1)

F22Raptor, if you're using Dan Townsend's latest .ecu for the '89 code, just wait a little and it should be added soon.

Scott, I'm pretty sure since I see DFCO at the dragstrip when winding down at the end in 3rd gear. Maybe your load value (LV8) isn't dropping off enough until you hit 1200 rpm. I've been watching and listening for DFCO quite a bit lately, trying out different RPM's and gears. It's definitely noticeable in sound at higher engine and car speeds.

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Greg Westphal
'87 IROC 305TPI/A4

Scott 88 GTA

Hmm, I guess I'll have to do a little more driving with the scanner hooked up and see what's going on.

The reason I'm looking at all of this stuff is because right now with the original ARAP bin, whenever I let off the gas the car does not slow down. It just wants to keep going. Am I looking in the right areas for this? Thanks.