02 Sensors

[mekelly]

I am debating whether to replace the o2 sensors on my 1994 Explorer.

Although I am not getting any codes my gas mileage is pretty poor. Maybe 11-13 around town, maybe 15-16 highway.

Engine runs great, idles great. I have replaced plugs, wires, air temperature sensor, both coolant sensors, filters, fluids, wheel bearings, brakes, fuel pump, etc. I am not looking to try to squeeze every .1 mpg I can get out of it, but am looking for repairs that could provide a marked improvement in gas mileage, say >1mpg.

I understand that slow or failing sensors on these 1st gens can cost you 10-20% of your gas mileage (not expecting that kind of a gain) and replacement/checking is recommended every 60,000 miles. I am sure these are original at 178,000 miles so I am 3x past the recommended interval!

Given that I can purchase both o2 sensors at Rockauto (genuine Bosch OE replacements) for a total of $48, I am not too worried about 'throwing' money at parts (I'll take the gamble at $48 that I may be replacing sensors that might not need replacing).

In my mind, new sensors vs 21 year old o2 sensors are a no brainer. Other than the $48 and the hassle of replacing them, any reason not to?

Also, I have searched the forum, but what are the best real world tips (for those that have done the job) to minimizing the hassle/frustration factor in this job? I have read to remove the starter for the drivers side and the front passenger tire for the passenger side to get to the connectors more easily. Others said to remove the coil pack. Other tips?

Finally, for those that replaced the o2 sensors on their 20+ year old trucks (especially those where the sensors weren't necessarily throwing a code), did you see any improvement in mileage, engine performance, etc.? Did you go with the original wire length or the sensors with the little longer wire?

 

[2stroke]

I replaced my o2 sensors which I'm pretty sure were original. I was having a problem of one bank lean, and one rich. What I found is that one O2 had backed out, and I unscrewed it by hand. I would bet that is why it was acting weird, not because it had gone bad. That said, O2 sensors don't cost that much, and replacing them on these is reasonably easy. I had always gotten a consistent 17.5 mpg highway with my truck, and after the new O2's (I used NTK, which I highly recommend at $25 each from rock auto) I get have been getting 18 mpg highway now, which is on par with every other 4.0 I've had. The only time I've ever seen 20 mpg (other than a fluke), is driving a steady 55-60 mph with next to no stops. 65-70 mph, I've never had one average above 18 mpg.

 

[mekelly]

Thanks 2stroke, that's what I was looking for. I don't expect 20mpg on this truck but I would love to get 1-2 more mpg in the city and on the highway.

If I could get a consistent 14-15 in town and 18 on the highway, I'd be happy!!!

Any tips on how to get to the connectors easier? That's seems to be the toughest part of the job.

 

[natenkiki2004]

On our vehicles, they're a turd to test. If you're going to crawl underneath to test it, may as well throw a new sensor on. If it's factory original, it's probably due for a replacement. This is one area you want to use OEM Motorcraft.

For what it's worth, the one I picked up was a NOS Ford F4UF-9F472-CA.

 

[mekelly]

Bosch makes the Motorcraft o2 sensors. They're half the price for the same sensor!

 

[natenkiki2004]

Bosch makes the Motorcraft o2 sensors. They're half the price for the same sensor!

HP makes Compaq computers but they're still pieces of crap. Every company makes varying quality parts. If you go with OEM, you're going with what the Ford engineers designed.

Cost is a good reason to go aftermarket but you'll note I didn't say buy one new from the dealer. I found mine NOS, that's what I would suggest doing first. If you can't find one then buy the highest quality aftermarket unit you can find.

If you plug my part number in, you'll find a Motorcraft unit for $40 on RockAuto, the Motorcraft DY733. Those can be found on eBay for $25 as well. Are they the same? I don't know. I paid about $40 for mine to make triple-sure it was the right part number.

I don't know that I'd go with Bosch, NTK/NGK has a pretty good reputation.

 

[mekelly]

I hear ya. I am all for buying the manufacturer's part when everything else is equal. What doesn't make sense is to pay 2x for the same part.

I spoke with technical support at Bosch who confirmed they are the OE supplier for the Motorcraft sensor; they ARE the same part. The Motorcraft sensor is simply a re-branded Bosch. Some distributors/sellers will mark up the price and offer a better warranty. You see that between Autozone and Advanced Auto sometimes.

I agree that you could be getting a Chinese counterfeit knock off or something else on eBay but I am confident that buying from Rockauto eliminates that risk.

I am always wary, and try to do my research on critical engine parts. In this case, you buy Bosch, you're buying Motorcraft, but that's what's great about this county, the free market and the freedom to buy what's best for you!!!

 

[natenkiki2004]

That's true to some extent. No auto manufacturer makes all the parts. They design and engineer things and contract them out to other companies. Sometimes you can buy the contractee's parts and end up with the same quality. Other times, you're buying an more general-purpose part. It's likely that both will work. The majority of problems you'll get will come with cheap parts like universal O2 sensors that you have to splice in or Standard Motor Products T-Series parts. They're budget and they'll likely work but maybe you replace all the sensors with aftermarket parts that have lesser tolerances and cause some weird issue or the parts simply fail.

Anyway, a quality Bosch will probably outlast many other parts in your vehicle. It's great that you do research, you need to be aware when buying parts. There's a lot of crap and dishonest sellers out there.

 

[mekelly]

Amen to that!

 

[2stroke]

You are absolutely correct you need to be careful what you buy, but Motorcraft isn't OEM. Its aftermarket just like Bosch or Champion or anything else. Motorcraft is made exactly to Ford specs, however, and is always top notch quality. Actually if you look at the original O2, it says Bosch right on it above Ford. You can run Bosch, NTK, Motorcraft, AC Delco, or any other number of quality brands and be just fine.

I have only run a few NTK O2 sensors, but have run hundreds of NGK spark plugs. I have never had a bad NGK/NTK product ever.