Car bogs and breaks up when going to closed loop - ZR-1 Net Registry Forums

LGAFF · 04-04-2021

My 91 runs well when started up in open loop, alittle rich, but as soon as it goes to closed loop the cars bogs and breaks up. The Left 02 will oscillate, but it drops down as low as .018 V for short spans ... there is no apparent leak, I changed the 02 with no change, I verified 12 volts at the power source(AC fuse is fine) and continuity with the ground, I also tested ckt 412, when I jumpered ckt 412 to ground with the car running it produced .020 Volts(manual says it should be under .200). There is also no check engine light.

Any thoughts? I am going to replace the connector and see if it improves

Mikey · 04-04-2021

What happens if you just leave the o2 sensors unplugged

LGAFF · 04-04-2021

runs in open loop and is fine

Mikey · 04-05-2021

Has the wiring been cut, spliced or repaired at any point?

LGAFF · 04-05-2021

It has not

LGAFF · 04-07-2021

ECM tested on another car and it was not the issue.... O2 sensor behavior was completely different that I see on my car.... back to the drawing board. Going to swap the right side and see if it changes....

04-04-2021	#1
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Car bogs and breaks up when going to closed loop My 91 runs well when started up in open loop, alittle rich, but as soon as it goes to closed loop the cars bogs and breaks up. The Left 02 will oscillate, but it drops down as low as .018 V for short spans ... there is no apparent leak, I changed the 02 with no change, I verified 12 volts at the power source(AC fuse is fine) and continuity with the ground, I also tested ckt 412, when I jumpered ckt 412 to ground with the car running it produced .020 Volts(manual says it should be under .200). There is also no check engine light. Any thoughts? I am going to replace the connector and see if it improves __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

04-04-2021	#2
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 362	Re: Car bogs and breaks up when going to closed loop What happens if you just leave the o2 sensors unplugged

04-04-2021	#3
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Re: Car bogs and breaks up when going to closed loop runs in open loop and is fine __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

04-05-2021	#4
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 362	Re: Car bogs and breaks up when going to closed loop Has the wiring been cut, spliced or repaired at any point?

04-05-2021	#5
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Re: Car bogs and breaks up when going to closed loop It has not __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

04-07-2021	#6
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Re: Car bogs and breaks up when going to closed loop ECM tested on another car and it was not the issue.... O2 sensor behavior was completely different that I see on my car.... back to the drawing board. Going to swap the right side and see if it changes.... __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359