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Discussion Starter #1 (Edited)
Hey guys, I think it's about time I replaced my O2 sensors seeing how they're the originals with 115,000 miles on them. Not to mention I've had a pretty persistent detonation issue I haven't been able to shake completely by conventional means; MAF cleanings, seafoam, plugs/wires, etc. only took care of 90% of the problem. I had to retard the spark 2 degrees in my tune to get it to stop and I can't go with higher octane fuel because the tune is already for 93 which is the best you can get around here.

Anyway, to the point. I read on here that any universal 4 wire O2s will fit the bill, and as such I found these on ebay:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=390079782705

Those are apparently "BWD" branded, so I Googled it and a few things came up saying they aren't the best quality. A set of four of those would run me $93.80.

RockAuto's cheapest O2s (with the proper pigtail) are by "Denso" for a few dollars more; with the 5% discount a set of four of those would run $124.

The other alternative is to just get Bosch, for about twice the $$$.

So what's the best option? I want to be sure the O2s aren't contributing to my detonation issue after I do this, so I don't want to end up with crappy parts. I'd also like to spend as little as possible to get the job done right. High demands, I know... :rolleyes:
 

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Denso makes good parts. I usually get motorcraft for ford o2 sensors. I do lots of AC delco on chrysler and GM cars. It sounds like the Densos are a good deal though for all 4. I say get those!
-Rob
 

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I can see why you want to replace all the O2 sensors, but I would start with the front's first (I am actually doing that as soon as I get my 2 bosch's from rock auto). If you have a code reader that can read live data try and make sure the voltages are within .2-.8 mili volts

As for brand's, Motorcraft is best, but I found from other members, well read the quote from my thread.

Just so you know Bosch makes the O2 sensors for Ford. I had to replace them on my '97 Mountaineer a year ago. It had a Ford part # on it but it also had a Bosch logo on it
Seeing as how O2 sensors are so important to how your engine performs, and hard to change, I'd rather get something that will last as long as my current ones have (over 90k).

P.S. check what your air charge temperature sensor is reporting to the engine. I recently cleaned mine with maf cleaner because it was telling me it was 70 degrees for my intake air after a warm up cycle(I was able to clean off visible dirt). Right now it's about 40 degrees outside. However no one ever mentions this in their cleaning routine, so take this advice with a grain of salt.
 

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Discussion Starter #4
There are plenty of things that can cause spark knock on a stock motor. Carbon build-up in the combustion chamber, running too hot, a dirty/faulty MAF sensor, vacuum leak, faulty oxygen sensors, faulty air intake or coolant temp sensor, weak fuel pump, plugged fuel filter, faulty fuel pressure regulator, clogged/dirty injectors, and bad plugs/wires. You've already addressed or plan to address some of these, but you've still got some work to do.
Well, out of all of those issues I've already addressed these:

Carbon build-up in the combustion chamber - Sea Foamed the top end twice. Also Sea Foamed the oil with my last change.

running too hot - Flushed the coolant system recently, new 50/50 mix and a 180 degree thermostat. Running temps also verified with XCal2.

a dirty/faulty MAF sensor - 04 GT MAF installed (technically from 04 F150 w/30k miles), is clean.

vacuum leak - All vacuum lines replaced recently.

faulty air intake or coolant temp sensor - Sensor input to computer verified to be accurate using XCal2.

plugged fuel filter - Replaced fuel filter recently.

clogged/dirty injectors - Sea Foam run through gas tank twice recently. No lean codes.

and bad plugs/wires. - Plugs and wires replaced 9,000 miles (10 months) ago. I will pull one off each side and check them to be sure they look good.

That leaves bad fuel pressure regulator, weak fuel pump or bad O2s as the possible problem(s). I've gotten a couple intermittent codes related to O2s in the past year or so...
 

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Get 2 Motorcraft sensors (DY761) for the fronts and be done with it. The best you can get and you can be sure that they will read accurately, switch quickly, AND last another 100k miles. You can get the pair for about $100. The rears aren't important.

Since you have the XCAL2 now, you can look at the long-term fuel trims. They should be 1 if everything is in good order. The chances of both sensors being "shifted" rich or lean to cause spark knock while having the computer think the LTFT are 1 are remote.
 

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I have Denso's in my bird. Whenever I buy o2's I always get Denso and have never had a problem with them.
i've also had very good luck with Denso, not so much so with Bosch. Denso supplies to Toyota and Lexus, so that says a whole lot. I called their customer service and they have a special process to make their units last longer and perform even if there are contaminants. Motorcraft is also excellent, but I'm sold on Denso because of the price.

http://www.densoaftermarket.com/oxygen-sensor.php
 
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