NB O2 Issues EBL EFI Crazy Constant Readings
#1
Member
Thread Starter
NB O2 Issues EBL EFI Crazy Constant Readings
"84 Crossfire Vette, Renegade, 90# Injectors, programmable ECM from Dynamic EFI, other mods... - Wrestling with heated NB O2 readings. Initial problem O2 was reading constant 459 MV's, replaced it with a new heated Bosch and got constant readings at about 60 Mv's. Found what I believe was an intermittent short in the ECM connection wire soldered it and tested continuity got 1/2 ohm so I assume it was a good fix. Still wasn't getting any movement . Replaced the Bosch with a used AC Delco AFS74 which bench test ok (propane & ohm meter) and that one also isn't reading. It's stuck this time at near 1000 MV's. Crazy. Have a WB that is working so I can compare another reason why I know when NB readings are bad.. Anyway, anyone have a clue what might be going on here ? ECM issue? Should I run a new ECM wire? Thanks.
Getting tired of jacking the car and playing with the sensor, as you might expect.
Getting tired of jacking the car and playing with the sensor, as you might expect.
Last edited by Cartrax; 07-14-2020 at 02:15 PM.
#2
Supreme Member
iTrader: (1)
Re: NB O2 Issues EBL EFI Crazy Constant Readings
The O2 sensor circuit has a dedicated ground point from one of the ECU pins that I believe runs to one of the studs on the back of the cylinder heads (on the F body.... Vette.... IDK). Check that you have a solid ground for it. Should be in your diagrams somewhere.
GD
GD
#4
Member
Thread Starter
Re: NB O2 Issues EBL EFI Crazy Constant Readings
Looked and found the O2 ECM ground - checked OK. After that for kicks I played back my last data log and sure enough at idle I was getting a near constant 986 MVs as the WB is telling me my AFR is in the high 13's. Duh, the NB was giving me an accurate read cuz I'm idling a bit rich. My head was wrapped around the other two sensors that wouldn't budge off lower readings and I assumed this was happening again but stuck at a high reading. Anyway continuing to watch the diagnostics and examining the log dump I found the NB doing exactly what it's supposed to do - when the WB AFR cracked 15's the NB responded with voltage drops, consistently. So back to the tune finessing now that I know both O2's are functioning - just need to figure out what to do with "em.
Last edited by Cartrax; 07-15-2020 at 10:49 AM. Reason: deleted pic - unnecessary
Thread
Thread Starter
Forum
Replies
Last Post