I'm wondering how much the shielding on the end of my O2 wire coming from the engine harness side matters? Before my TII swap happened the O2 wire got crimped off when the UIM got bolted down to the LIM. My question is how much does that amount of shielding matter? I crimped an extension on to reach the O2 sensor and the crimp starts about where the front corner of the upper and lower intakes on the passenger side.

I'm replacing my O2 sensor and while doing it i'm wondering if I should repair the missing shielding as well? Right now there's just an extension wire crimped on...probably 12ga. wire. Can one of the electric gurus chime in and tell me how important that bit of shielding matters?

Also, I have a CEL of 17 that I'm trying to track down. The FSM reads "Oxygen sensor output remains 0.55v 10 sec. after F/B system operation begining" Is this related to sheilding? Could it be that simple???

I added some pics so you can get a feel for where the shielding was lost and the crimp I put on.

 

In the spirit of spreading information. If anyone finds this thread searching for similar issues they are having. I found this website while searching for answers...

http://www.aa1car.com/library/o2sensor.htm

 

I don't think missing this small amount of the shield is going to do any harm. Give it a try. I'd be more worried if the shielding that was missing was crammed in with all those other wires in the EM harness.

I am no electrical engineer etc. So take it for what it's worth. This ain't no F-16. Then it would matter..a lot. Hell, until recently you couldn't splice a shielded wire on an airplane without getting your *** run off.

 

The missing shielding isn't going to matter. Take an ohm meter and check to see if by any chance the shielding is grounding the current. Hook up the meter at the ecu pin and the O2 sensor connection to check. That shielding can in no way come in contact with the wire carrying the current, or it will go to ground and no signal will reach the ecu.

Some have even gone straight from the O2 sensor through the firewall and into the ecu to avoid the harness and broken wire problem.

 

Thanks for the replies. I"ve learned to ask about small details cause too many times I"ve thought something was insignificant, only to find out down the road that my oversight caused bigger problems down the road.

Perfect example: When I was in high school a friend was helping me change the breaks on my 626. He was a american muscle owner and shadey tree mechanic. Apparently with old muscle cars when putting drum brakes back on you tighten down the nut over the wheel bearings, then turn a quarter turn or so back, put the cotter pin in. We did that on my 626 and 8 months later I had to replace the bearings....apparently on my car you tightened down all the way.

I haven't had time to test my 02 sensor, but can someone translate what the FSM is saying about my CEL 17: "Oxygen sensor output remains 0.55v 10 sec. after F/B system operation begining" I think I"m correct in thinking .1v is lean and .9v is rich. So the CEL and FSM is telling me that my engine is running too rich 10 sec. after startup???? Is that a correct assumption and translation?

 

As stated above, first check for continuity in that circuit. Connect a mm at the ecu end of the harness and at the O2 connection and make certain that the circuit isn't grounded, or as that wire is very, very, thin, there isn't a broken wire. Either will cause a cel.

 

FB is FEEDBACK. What they are trying to say is the 02 sensors output isn't reaching the ECU.

I'd start the car and backprobe the pin for the 02 sensor at the ECU plug. The reading should be like you indicate, from 0.1vdc to 0.9vdc.

What you read depends on a couple of things. IF there is no airpump and ACV, then the reading at idle might be close to .7vdc to .8vdc. IF the airpump is functional and the ACV is functional the reading will be LEAN like .1vdc give or take.

IF this is a NON TURBO car and the airpump and ACV are functional, what you could do is disconnect the connector on the Relief solenoid (BLUE in color). Then the 02 reading will not be the lean .1vdc I indicated above, but go to the rich side, like .8vdc give or take some.

Usually Feedback is related to actually driving the car at steady speeds and the ECU/02 sensor going into Closed Loop. When in closed loop the 02 reading will vary on each side of stoic to try to maintain a AFR of 14.7afr. Something like that.

You could idle the engine. Then pull the connector off the 02 sensor and read the one wire output with your meter. Then reconnect the sensor and go to the ECU and backprobe the 02 sensors input wire. Reading should be the same.

 

Thanks for pointing me in the right direction. It's been storming on and off like mad all day and the car is sitting outside.

The car is a S5 JDM 13B swapped into an 89 vert. My signature has some of the info about the car. My airpump and ACV are both removed. The car has been sitting for over 2 months so I have to dig up notes and check things to refresh my memory. I'll have to look into the relief solenoid status.

Not sure if this is a factor or not, but I"ve got an FD fuel pump and 800cc secondary injectors. I haven't added any fuel control yet. But my understanding is that the car shouldn't run rich until the secondary injectors open up.

I'll get some diagnosis on the sensor, ECU and continuity when time and weather permits.