Having issues with bucking and sputtering with my 90 L98 in open loop only. Car runs fine in closed loop. Does anyone know what sensors the ECM uses in open loop operation?

Thanks

 

Open loop cold or OL WOT?

Same sensors.
In OL cold , the ECM doesn't reference the O2 sensor to make fuel adjustments, fueling is from a fixed calibration
OL WOT is different again

 

Open loop cold. Any suggestions as to what is causing this?

 

After reading some additional threads, it appears that my issues are likely due to a bad CTS and/or MAP sensor.


Does anyone have any baseline values for what I should see in open loop for these two sensors? Using Diacom.

Thanks,

 

Some sensor values
http://www.corvettebuyers.com/c4vett...nformation.htm
https://www.thirdgen.org/forums/tbi/...or-review.html

The CTS you are going to have to check with a DVM because Diacom only displays the converted temp figure

 

Still having issues with sputtering and power loss in open loop. Car feels like it hits walls at certain RPMs and is way down on power. As a refresher, note that the car has new plugs, wires, cap, rotor, ignition coil, o2 sensor and FIC Bosch injectors. I have also replaced the CTS which did not seem to help this problem.

Once the car reaches closed loop and is up to temperature, drivability improves greatly.

At this point , I feel that possible causes could be a vacuum leak or bad EGR. I also plan on getting a fuel pressure guage just to rule out any fueling issues (although I would think a fueling issue would be present in both open and closed loop).

Any ideas?

 

Are there any codes showing up?

 

No trouble codes. Have Diacom software, but the laptop display recently died, so I can't log any data presently.