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Should I replace oxygen sensor?

G

GrandprixSteve

New member
I have an 04 GT with only 60k miles. The last 10k miles I've been running with a cooling issue I didn't have time to run down. I fixed it earlier this week. Flushed the coolant, new tstat, changed the air and fuel filters, plugs and wires. Ran a dose of techron through it. Car runs better than it has since I bought it with 30k miles. Actually, I'm amazed at how good it's running.

I'm wondering if I should go ahead and replace the O2 sensor while I'm at it all. It hasn't thrown any codes but given that it's been running lean for a while and the age of the car, would it be a total waste of time/money to go ahead and get it out of the way? If yes, any suggestions on brand?

While I'm here, anything else I should take care of looking ahead to the next 60k miles?
 


I'd say leave it, if its running good.

Did you use stock replacement plugs (ac delco)

Well since you've gone this far, lets do 2 more things.

Take the throttle body off and clean it, along with clean the maf with maf cleaner, youd be suprised how dirty both get in a short time.

Also if you have not changed the trans fluid yet, I suggest you do it. NO FLUSH, just buy a filter and 8 quarts of dexron 3 and do a pan drop. Its a good idea to do it now, because the fluid is old.
 
OK - I'll save the 75 bucks and leave it be - thanks for the tip.

I used AC pro iridium plugs but I used AutoZone Duralast wires. After a little reading here, I'm concerned about the wires. Any thoughts? I don't mind switching to stock delco, I've go the time and money now to do it if it's worth it.

Funny you mention the throttle body - I had the "struggling to start" issue about 6 months ago which got me on this forum in the first place. Cleaned out the TB and worked like magic. Prob wouldn't hurt to re-check it though.

OK on the trans fluid. I read here that it would be a good idea. You suggest dexron 3 over 6 - I've seen 6 suggested? Will I need a new gasket or can I reuse the old one?

Thanks man.
 
Oh yeah - thanks for the MAF suggestion. I saw some MAF cleaner at O'Reilly's the other day and wondered if it was worth anything. So just spray it on the screen-like element in the intake?
 
Correct, just take the maf out and spray it down.

I suggest dexron 3 because thats what was in it from the factory, dexron 6 came standard in mid 05 I think. If someone really wanted to you can put 6 in no problem because its interchangable.

But I just like to put exactly what came in it from the factory, because thats just me, and dexron 3 is about 1-2 bucks cheaper per quart.

The stock trans pan gasket is metal, clean pan/trans surface and metal gasket and just re-use it.

Get 8 quarts of fluid because a standard pan drop will take anywhere from 7-8 normally. I would start with 6.5ish and do the proper fluid level checking (trans hot and running) and add as needed.
 


GrandprixSteve said:
Oh yeah - thanks for the MAF suggestion. I saw some MAF cleaner at O'Reilly's the other day and wondered if it was worth anything. So just spray it on the screen-like element in the intake?
Click to expand...

No, you'll wanna use the straw to direct the spray on the tiny little wire elements going across the center of the MAF.. I always thought it was easier to get it from the open side rather than the screen side. Soak it good and make sure it is 110% dry before you reconnect any wires. Take the MAF and throttle body off the car all together to clean them, so much easier.

That way you'll be able to get the TB with TB cleaner from both sides, and use a cloth to wipe down the plate and insides of the passage...

The MAF works by heating that wire to a very specific temp, the pcm monitors exactly how much power it takes to keep the wire at that temp as air flows over it and cools it, and that combined with the IAT input and the defined volume of the tubing is how the computer knows how much air is coming through the intake, so when crud gets on it over time, it can seriously change the MAF readings. That's also why you DO NOT want to touch those little wires with ANYTHING... only spray them and let them air dry.

I also got a long tire cleaner and wrapped some paper towels around it, soaked it in tb cleaner and used it to wipe clean inside the plenum opening as far in as I could get.
 
FriboRage said:
No, you'll wanna use the straw to direct the spray on the tiny little wire elements going across the center of the MAF.. I always thought it was easier to get it from the open side rather than the screen side. Soak it good and make sure it is 110% dry before you reconnect any wires. Take the MAF and throttle body off the car all together to clean them, so much easier.

That way you'll be able to get the TB with TB cleaner from both sides, and use a cloth to wipe down the plate and insides of the passage...

The MAF works by heating that wire to a very specific temp, the pcm monitors exactly how much power it takes to keep the wire at that temp as air flows over it and cools it, and that combined with the IAT input and the defined volume of the tubing is how the computer knows how much air is coming through the intake, so when crud gets on it over time, it can seriously change the MAF readings. That's also why you DO NOT want to touch those little wires with ANYTHING... only spray them and let them air dry.

I also got a long tire cleaner and wrapped some paper towels around it, soaked it in tb cleaner and used it to wipe clean inside the plenum opening as far in as I could get.
Click to expand...

OK - I see what you mean. And thanks for the MAF explanation, I'd wondered how it worked.
 
Got the MAF and TB cleaned this morning. Although I cleaned it good in the fall, the TB was very dirty but not cooked on like it was before. A little Seafoam and it came up quickly. I cleaned about 3-4 inches into the plenum, too, as far as my hand would go. MAF was straight forward. Idles very nicely now - probably result of TB.

Will I notice any driveability difference after cleaning the MAF or is it just an MPG thing? Also, I've heard it takes the PCM a certain amount of time/driving to recalibrate to new/clean sensors. Any knowledge on how the PCM responds to this sort of maintenance? Just curious.

As for the trans pan drop. I have a couple of questions.

  1. Went to Oreillys this morning and they have Valvoline Mercon which says it is Dex 3 compatible - I didn't see anything that was specifically Dex 3 - so is Mercon what I'm looking for if I'm sticking with Dex 3. You were right FFDP - it's a couple bucks a qt cheaper. About 20 bucks a gallon vs 30 for dex 6. Here's a link to what I was looking at http://www.oreillyauto.com/site/c/detail/VLV0/D1/N0471.oap?ck=Search_N0471_-1_550&pt=N0471&ppt=C0207
  2. Also a question about trans filter. They have a Wic for 18 bucks. I know Wic makes good oil filters but they're not relatively cheap. However, the AC Delco is about 50 bucks. So does Wic make the same quality trans filters as it does oil filters? Whatever, what I'm asking is which should I buy given the difference is almost 3X?
 
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At napa it says on the bottle dex/merc I believe, so valvoline mercon is the same thing at oreillys.

And I always just use the wix filter, I think my cost at napa is 15ish bucks, so 18 sounds about right.
 


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