A couple ??'s

[Chuck Leeper]

Am STILL fighting this FAST tuneup I have.
Took the car to the dyno today. Never got it to show O2 correction. [Sensor was recognized]
1. It is my understanding of the system, that the afterstart vs cts MUST be at zero at or before the closed loop enable temp is reached, or the correction by the O2 will not take effect. Yes or no?

2. Does the decay rate have to be pulled down so that this added fuel is decayed out before the Clnt temp is reached?

I envision this:
I have to have the afterstart map sloped to zero before I get to my minimum closed loop temp of 160*. I must also have the decay set so that this slope is attainable prior to reaching 160*.
IF I leave ANY added fuel available by either, A: not reducing afterstart fuel to zero, OR B: not allowing it to get to zero by the 160* I've chosen, due to the decay being wrong, then the closed loop feature will not be activated, and subsequently, I will not have O2 correction functioning.

Someone please get this old man on the right track on this!

Next item: What in the world is coming out of my engine compartment to make the dyno RPM pickup go whacko and mess up the torque readings?? The readings jump all over, [regardless of the plug wire we hooked to, or the location of the pickup ground clamp] and the dyno read 1200+ Ft Lbs on one pull!!
I have done the following:
A. Installed a NEW GM coil and module.
B. New plugs at .028 gap.
C. New DIS4-HO. GROUNDED and done correctly!!
D. New plug wires.
We also unhooked the MSD and tried it again.. same results. We then hooked the tach to a 95 Z-28.. worked PERFECTLY!! This is a brand new dyno too!!

We tried boost at 20psi, and as usual, the engine was lazy getting up on boost, then climbed to max torque, went flat and finally made it to 6050rpm. During this struggle we managed a "mind boggling" 590 hp.
The turbo is a Turbonetics T72BB, w/ a "p" trim and a .82 hsg.. Anyone think this is the "flat spot" i'm seeing.. maybe due to hi back psi??

BOTTOM LINE?? Either this car is a friggin MUTT, or I'm ALOT older and dumber than I thot!

Any input is appreciated!!

Back under my rock...

 

[STP]

Chuck, I feel your pain on the wacky torque readings. Mine also jumped up to 1200ft/lbs on one pull. Never was able to get a good torque reading on the car until i started making the pulls in second gear. My car was trying to downshift from third into second (2004R) and apparently making the torque reading jump around. Heh, I printed the 1200ft/lb torque reading out just for bench racing : ) I am also running the DIS-4 grounded straight to the battery....

 

[Craig Smith]

Gee Chuck... you sure have a good way of making me want to stay young!

There is a simpler answer to your question regarding after start fueling and closed loop. When the after start fueling is gone isn't critical; it's only critical that it's gone. It isn't important that it decays out before or after any other event, so if you are working to get this to happen you may save your energy. If you look in any of the after start tables, you'll see a sensor called AFT CORR. This is after start correction. Once it drops down to zero, it's no longer a problem as far as closed loop operation is concerned.

If the ECU shows an a/f ratio, it can run in closed loop. If it isn't, the only possible culprit is something within the calibration file. The most common cause of this problem is with the closed loop high and low RPM settings. How are yours set?