Originally Posted by 97Z-M6

about 3000 . i need some more track time to get it right.

my 60s suck

Originally Posted by Injuneer

OK.... try another approach.

Reference:

How To Understand, Service and Modify Corvette Fuel Injection & Electronic Engine Management, by Charles O. Probst.

This manual is authorized by GM, has a forward by Dave McLellan, Corvette Engineering Director. The manual carries a GM Part #12497977

Read Chapter 5 "Control Module - The Brain", Section 5 "Fuel Trim", Para. 5.2 subsection "Fuel Trim" (page 111):

And, read Chapter 8, Section 3 "Open Loop", para. 3.3 "Acceleration Enrichment". (page 177)

Not sure what your continued reference to operating the PCM outside its parameters by forcing it into PE mode at idle proves. What "target" A/F ratio are you programming for? Why is this in any way relevant to WOT operation?

You are also incorrect on the PCM using Cell 15... It (generally, there are exceptions based on EEC operation) uses Cell 15 only if the PCM was "adding" fuel through the BLM's in that Cell. If it was cutting fuel, it will default to Cell 18 in many instances. Yes, it uses what it learns (Cell 15 or the algorithm calculated Cell 18) in closed loop to adjust the fueling in PE mode.... everyone knows that. But is also disables learning, and I have yet to see, in any scan that anyone has ever sent me, a non-128 value used in PE mode.

Originally Posted by bunker

No, decreasing timing will make the combustion chamber temps lower but increase header primary temp, trust me, try putting in 0* of advance & see how hot your headers will get, they'll start to glow because now when the exhaust valve opens the cumbstion is not yet over & will continue to burn in your exhaust because you fired the spark plug too late in the event.

Now, as for widebands, if I'm in closed loop & let the o2s do their job my LM1 will read 14.7 at idle, so I'm sure it has no problems reading my exhaust at idle, then again my idle is also at 1000rpm & I have an o2 bung welded after the Y-pipe where the LM1 o2 goes in, & when I run it in open loop & o2s are at 100mv or so then LM1 reads 18:1 A/F so I can go by that.

The other thing, I keep running into these problems if I want to tune idle for PE:

To me it doens't work, reason being is even though my BLM's are locked to 128 for WOT, at idle the STFT still work for some weird reason & they compensate, I can easily tell this because when I come to a stop my o2's will read 100mv for a bit & then all of the sudden they start jumping around again, I can see why because the STFT are correcting event though the LTFT is locked at 128, its easy to see cuz when I come to a stop the injector duty cycle hangs around 1.6 & the o2s at 100mv where I want them, then all of the sudden the o2s start jumping around & the injector duty cycle is back to 2.1 where it would hang out in normal closed loop aswell, & if I lean the PE table out more within a few seconds of comming to a stop the injector duty cycle will come back to 2.1 again, if I returne just normal closed loop & disable PE the injector cycle now no longer goes to 1.6 when I come to a stop & then 2.1 but it just goes to 2.1 right away & stays there, so no matter what, for me in closed loop I still get the darn correction taking place.

The other problem? this one is funny, when I come to a stop, for those few seconds that the injector duty cycle is at 1.6 & the o2s are at 100mv I get a DTC (fuel system lean) & engine light comes on, then injectors go to 2.1 & engine light goes away. My STFT go to 150 at that same time while the LTFT stay at 128.

Matt.

Originally Posted by 97Z-M6

im not trying to argue, im just stating my findings, thats all.