While driving, my SES light will turn on, and off. Not very frequently, atleast a few minutes on and a few off. The code Im getting is 13 so I replaced the O2 sensor, but this behavior hasnt changed. When the light is off, the car does appear to be running in closed loop.

I used to be able to jiggle the O2 wire and this problem would go away for months at a time. Is it uncommon for this wire, that runs right next to my Y-Pipe to go bad? Should I just cut out the old wire an splice/solder a new one on? Or could the ECM be freaking out?


Its a 86, 2.8L

Thanks Guys

 

If you have an ohmmeter, you can check the resistance (if any) between the exhaust pipe and the engine, in case the pipe is losing a ground connection.

 

Ok I am having trouble getting any continuity on the pipe with my tool, I'll try again when i can see better in the morning.

I reset the computer, and drove around with WinALDL. My O2 Voltage barely deviates from 450mV, which is normal in open loop right?

Right before the Code 13 and the car showed a closed loop flag, the voltaged ranged from 380mV to 557mV. Shouldnt it be a much wider range?

Would the winaldl data help? Theres a lot of it.

 

Yes, the band should be much wider with an active O² sensor. And yes, 450mV is about the bias voltage of the sensor. The fact that you got the closed-loop flag immediately before the DTC13 tells me that the ECM is sensing the signal but not accepting the range. That resistance reading might be significant. It may be a little Rube Goldberg-esque, but you could try stripping a length of wire, bolting one end to a good engine ground, then wrapping the other stripped end around the sensor shell (maybe even wire tying or taping it in place - niether will last long in the heat) to see if the signal level improves. If you get a stronger signal with the separate ground, you may need to loosen the exhaust manifold bolts, coat them with anti-sieze, and reinstall them to try to improve the ground. Later models with three- and four-wire O² sensors eliminated these problems by providing a ground right at the sensor leads.

 

Just had another thought. You may also have another failed sensor, especially if there has been any engine work requiring new gaskets, and an incompatible RTV sealant was used. The curing agents in non-sensor safe RTV can ruin the zirconia sensing element in an O² sensor in short order.