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95 940 bogs when accelerating

Boonestafa

Member
Joined
Sep 14, 2019
Location
Hanover, PA
Hey all, I have a 95 slick top 940 with the base b230fd engine. I bought this car as a project from a guy that had been in the process of repairing her and got tired of this issue. Currently the car bogs badly when cold. After letting it idle and heat up the car will drive for 8-10 min or so without issue. After that it falls on its face and will hang and big from 2k rpm until about 2500 rpm after which it will rev pretty freely. The car has a cel and the only code coming out of the a side of the test block is A-212 which from my research is an 02 sensor issue. I took some measurements onboth the car side of the harness and it looked good coming from the car. The sensor itself put out about 200 mV at cold... but after warming up a bit went dead. What I read is it should be ~.9vDC. This was done with the heater unplugged.. I could get some sharper probes and pierce the shield if that?s necessary. Any ideas?

Also... I have another o2 sensor that was in the back of the car... Im not sure if it?s the correct part number...
Thanks in advance for the help!
Curran
 
Well, that sounds an awful lot like you've found your problem. Change it out and try resetting the ECU by leaving the battery disconnected for some ~30 seconds.
 
Pegged at 200mv is lean. (Or a bad sensor) 900 mv is rich.

Try a snap throttle. It should go rich, then lean out, then return to normal. Normal is oscillating between 100-900mv.

Confirm 12v between the two white wires, key on. This confirms the heater circuit operation.
 
So the o2 sensor could cause my symptoms?

The heater circuit is being provided at least 12VDC... I’ll try the throttle test in the morning. More importantly, what is the correct mounting point for the o2 sensor? Currently the sensor is mounted at a bung at the front of the CAT. There is another bung another 3-4 inches upstream. Should I move it?

Also the sensor that is mounted in the car is a p/n 965261. I have a p/n 965201 that came with the car. Is that the correct replacement?
 
Bumping this back up, as I have the same issue with my 95 945 with the B230FD. I have correct voltage through the heating element harness wires, but only .1v to .2v on the sensor lead from the oxygen sensor.

Has anyone used the mustang(universal) oxygen sensor with a car that has EGR and PAIR? I have searched for universal sensors with the 230FD, and came up inconclusive.

I'm seeing about a $75 difference in what are seemingly the same sensors, just one has a lot longer wiring harness.
 
For anyone searching, a Bosch 13942 works on a b230fd. I spliced the harness of the old sensor with the new one and the bog while accelerating is gone.
 
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