running rough and getting bad smell from exhaust on 2000 ford explorer sport

[nitrowizard88]

Hello,
I have a 2000 ford explorer sport 4.0 ohv. The other day my car started running rough all the sudden. Thought it was bad gas. Not the case. I changed the fuel filter and that didn;t help. I have recently gave my car a tune up with new plug wires and all. So I know thats not it. I am assuming its one of three o2 sensors. Could I be right in assuming this based on the bad smell coming from the exhaust aka bad fuel mixture?

[shorod]

With the information provided, my first thought is intake manifold gaskets.

Does it run rough like a misfire? Have you checked for diagnostic codes? Does the idle hunt or just run rough? Are you certain all plug wires are secure? Did any of the items you replaced make a difference of any sort?

-Rod

[nitrowizard88]

I got a computer diagnostic. I got a 1704 code. 02 sensor #2 bank #1 sensor. Going to pick on e up now...will try that.

[shorod]

Was it a P1704 or a P0704? A common assumption to make is to assume a code for "B2S1 HO2S Lean condition reported" means the O2 sensor is bad. That is not the case, and quite often far from it. That indicates the O2 sensor has identified an issue, but often the problem is due to a vacuum leak or misfire condition upstream from the O2 sensor.

-Rod

[nitrowizard88]

Thanks for the reply. OK I replaced the 02 sensor and you are right. It did not fix the problem. So whats the best way to check for a vacuum leak? I have new spark plug wires but I guess there is a chance it can burn through again. Ill check that again also. Thanks again for the reply.

[nitrowizard88]

oh and also..it was P1704 code

[shorod]

Please double check that code. A P1704 code is a transmission gear shift position issue, not a code related to a oxygen sensor.

-Rod