After a wot run if I get out of the throttle my afr goes 18+. I've been told this is normal and a non issue? I was wondering if it possible to correct this and if so how if it is an issue? I'm running a 6E with TP5.

 

Most likely going into DFCO, should be a flag for it in the data stream. Or look for an injector PW of zero.

RBob.

 

I see alot of DFCO settings in the scalers for RPMs/LV8/VSS/TPS/Temp.
I'm thinking the easiest way to disable would be "DFCO Disable if Temp Less then" set to -40F. If I change that -40 to say 250*F it would disable DFCO and goto Stoichmetric AFR????

Or am I better off leaving it as is and letting it leaning out to 18+ on decel?

 

when it goes into DFCO, its way leaner than 18-1 and completely normal.
i would leave it alone as it saves gas during coast down.

 

Ok, guess I'll leave it, one more thing. Is the lean decel of 18+ normal lasting until the rpms get very low. Guess it makes sense the engine pulling in air from coast holding the rpms high. It seems to richen up if I throw it in neutral.

 

yep, it shouldn't drop back out of DFCO until at least 1 of several conditions are met.
with your car having a MAF system, im not sure what all the conditions are.
on a MAP system like i have, besides getting back on the throttle, RPM, MAP, MPH, and probably 1 or 2 other things.

on my car with my rear gear, at ~60 and below mine will go into and out of DFCO during coast down if the trans is in fourth gear. it can be quite irritating because i can feel it when the fuel comes back on and shuts off.
if i shift into third gear, it will stay in DFCO until about 20~25 MPH.
fixing it so it stays in DFCO during coast down is something on my to do list.

 

DFCO is an interesting idea. Nothing wrong with it unless it's a performance engine with a stick tranny. In this case it can be abrupt when the fuel is re-enabled.

The main reason for DFCO is to protect the car-con. If no cat-con then it really isn't required.

The DFCO routines have a 'stall saving' action. This may be why it is going into and out of this mode. On an auto the P/N switch is usually monitored. Toss the shifter into N and the routine turns fuel back on.

There is usually also an RPM drop and MAP/LV8 increase that signals that the engine may be stalling. This too will cause DFCO to exit. Which then is re-entered shortly thereafter as the engine recovers, with the same result of off/on.

Max'ing the CTS threshold for DFCO is what I would use to disable it.

RBob.

 

That makes sense, after I make a wot pass the car surges. I'm thinking its do to the decel afr going from lean then the fuel coming back in. I might try to disable the DFCO by raising the temp it comes in and see if it runs smoother after wot.

 

on my car, going into and out of DFCO isn't really abrupt.
but enough that i can feel it, its not as bad as the TCC unlocking in decel and then relocking once back on the throttle.
if i didn't keep the TCC locked during decel, i probably wouldn't notice it.
BTW, RBob thanks again for helping me with that
(well over 100k miles on it since i started keeping the TCC locked in decel)
i would think its much more noticable with a standard.

im pretty certain mine drops out in forth gear on my car because of MAP, if i down shift i can keep it in DFCO till ~15 MPH.
some day i hope to get to the point to where its the thing that bothers me the most, then i'll get serious about fixing it, LOL.
right now the biggest irritation for me is why the ECM will sometimes command lean with the cruise control engaged.