O2 sensor cleaning?

[bigal0043]

Alright i posted this in another thread but no one replied so i thought i would make it in its own...

my car is running rich and getting really bad mpg... i checked vacum lines yesterday and they all seemed fine... so i am at the conclusion that it is my o2 sensor... i think after changing exhaust and moving the o2 i messed it up?

is there anyway to test an o2? i dont have any codes that i know of... in order for me to have codes the check engine light would come on?

is there anyway to clean an o2 instead of buying a new one?

 

[supra90turbo]

IIRC JetJock had posted about testing o2 sensors not too long ago. Try searching for "o2 sensor test" or something of that sort.

::edit::
You can also have codes stored without the MIL on, so jumper those terminals and see if you have any codes.

 

[bigal0043]

cool thanks i found his post and printed it out... going to try and do this test as soon as i can.. i hope its just the sensor gone bad....

other than getting it real hot is there anyway to clean one? like alcholol

 

[supra90turbo]

IMO it's cheap enough from MDC to not mess with it... $35 IIRC...

 

[jtamulis]

I sell 'em for $38 shipped. MDC no longer carries them, When he gets an
order I ship one of mine out. He charges $38 too.

Jeff

 

[bigal0043]

jt are they same as mdc where you have to splice into your old harness? they mount into the stock o2 spot?

btw how long do o2 sensors last? mine i belive is stock so it has around 120k on it

 

[jetjock]

120K is pushing it and then some. You can test in either in or out of the car but with that much mileage it's way over due for replacement. Don't be surprised if replacing it doesn't solve your problem though. Are you getting any codes?

 

[bigal0043]

i havent checked but i dont have any check engine lights on...

 

[jetjock]

The lambda sensor is monitored three different ways (all of which will turn on the MIL) so if it was at fault you should have some codes. Plus the engine will run only slightly rich if the sensor has a problem or becomes disconnected.

It's important to remember the ecu doesn't just whack out when a sensor has a problem. This applies to almost (but not all) every sensor on the engine. It "knows" what to do in that event and switches over to using internally stored values in place of the bad sensor. Generally speaking, most of the time these values are close enough that a change in engine operation is not noticable.

There are very few things that can go wrong that'll "overpower" those values so that's why I feel your problem lies eslewhere. That said, your O2 sensor should be replaced just on age alone.

 

[bigal0043]

well its only a recent thing where my mpg has really declined... thats why i assumed to be the o2 since i had to take it out when i did my exhaust.. moving it around... any other ideas then... i dont believe i have a vacum leak i dont get boost spikes and i boost to 10-12psi depending on weather... i wont hit fuel cut till around 14-15psi...

 

[jetjock]

Let us know what you find. A lazy sensor, such as one would be at 120K, could cause reduced fuel economy but the car won't run overly rich. The sensor could be lazy enough not to set a code. You could check it with a voltmeter as per the TSRM. Look for a minimum of 8 counts in 10 seconds with an average voltage of 450 mv if you do that but since it's so old you should replace it whether it's at fault or not. Good place to start.

 

[mrnickleye]

You should test the fuel delivery system. Fuel pressure, and pressure drop. Perhaps an injector is leaking. Today we had a nissan with an injector stuck wide open. Dumped fuel into engine like crazy.

Shit happens, parts fail, and I make a living.:biglaugh:

 

[GrimJack]

I'd bet on a crack in the IC pipes somewhere, more than likely off the bottom of the turbo. I had the same thing, and my mileage was terrible until I found it. Still boosted no problem, though.

 

[bigal0043]

i doubt that i have a crack on my lower ic pipe or any of them... they are hard pipes and thus no cracks... i checked the connections and they were fine... after i get my new o2 i will check my mpg again... i hope its just the o2...

but keep the ideas coming!!!

 

[csr ma71]

I just used some paper towels to wipe my sensor. It was all black, and after all the crud was wiped off, it still looked shiny gray like brand new. Went from 13 mpg to 17mpg. Also put some of that blue weatherstriping seal paste on the gasket like my hyphy BAS bro Boostaddctn told me to do.

 

[jetjock]

Blue weatherstipping paste? I hope it didn't contain silicone. If the gaskest is leaking the air drawn in will drive the sensor lean causing the ecu to inject more fuel so I can see that but wiping the sensor does nothing.

 

[bigal0043]

the elbow i got came with a new gasket so that wouldnt be a problem