After tracing down the problem in my 90 Jetta GL 1.8 fi (D2), to a bad O2 sensor my question is intill I get this fixed what harm, if any. will I do to the motor if I run the car with the plug unhooked? Thanks
As far as I know, you may run a little rich and you'll flunk an emissions test, but you should be OK.
Basically, when an O2 or temp sensor is disconnected, the ECU goes into an open-loop default setting sothe engine will run (without all the adjustments it would normally make to keep emissions down to spec).
Keep in mind that you may also idle a little higher than normal. This too is normal when running in this open-loop.
And you also might trigger a fault code and a "check engine" light if your car is so equipped with an OBD system.
But most *expensively*, you'll poison your catalytic convertor. How long this takes, I dunno, but it will wreck the cat. eventually.
Most of the damage will be to your fuel economy and catalytic converter. Is your car runs like mine (D1) did with the O2 sensor off, it will hunt for a proper fuel amount. It would run lean for a second then BAM! it pour in the gas until I let off the accelerator. I drove it about 5 miles to the shop. I wouldn't want to go much farther.
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