• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

940 Oxygen Sensor Troubles

MiniMotoSX

MiniMotoSX

New member
Joined
Jan 13, 2009
Location
Elk Grove Village, IL
So I tested my oxygen sensor the other day and it's giving me a reading of .3 volts. So in that case it's reading lean. I might sound dumb here but for some reason I can't get a hold of this, my car's mpg's are terrible right now so it's dumping gas. If the O2 sensor is sending lean to the computer it should be telling it to run more rich right? But other than that I have another problem. When I got my exhaust installed I wasn't paying attention to what they did with the O2 sensor and I found out that they actually welded it in around the nut so I have no way of taking it out of the pipe without somehow cutting it. Anyone ever have this problem or the simplest way of getting it out and putting a new sensor back in? Anddd one more thing, I tried following the sensor wires up to wherever it plugs into except I couldn't find it because I was underneath the car on a lift, so where does it end up plugging into?

Greatest thing now is the car won't even start anymore..
 
Simplest way to fix it. Unplug the O2 sensor, see if the car will drive, and if so: take it back to the shop and have them repair the absurdity. Even if you can figure a way to free the sensor from the pipe, odds are you will need to have a bung properly installed before you can have a sensor again, and that's going to take some welding.

Otherwise if it won't start, fix that first, then worry about the sensor. Start by checking for any stored ODB1 codes. The connector is up on the firewall right next to the dryer bottle, shouldn't be that difficult to find the wire and follow it up.

When replacing the sensor, I highly recommend the Bosch 15727, it's under 40$ delivered from Amazon.com, a 4 wires sensor, hooking up the 4th wire is optional. Normally with the stock setup, you can change the sensor without going under the car. Note that it is preferable to have the sensor near the turbo such as in the stock setup.
 
Thanks for that. Yea I checked the codes a couple of weeks ago and it came up saying about my o2 sensor and then another code about a faulty fuel injector. Do you think the O2 Sensor will stop my car from even starting?
 
MiniMotoSX said:
Thanks for that. Yea I checked the codes a couple of weeks ago and it came up saying about my o2 sensor and then another code about a faulty fuel injector. Do you think the O2 Sensor will stop my car from even starting?
Click to expand...

both the O2 and the injector could cause a lean condition. I would've started with the injector as it is before the combustion. If the injector is fixed...it might fix that lean condition that the O2 is picking up.
 
I put new seals on all of the injectors just for the heck of it. Didn't change much though. I think I'm going to actually test all my injectors possibly this week if I get a chance to.
 
MiniMotoSX said:
I put new seals on all of the injectors just for the heck of it. Didn't change much though. I think I'm going to actually test all my injectors possibly this week if I get a chance to.
Click to expand...

Test the spray pattern and pulse of the injectors, most likely the injectors are the problem and it is causing the O2 to do funny things. If everything else is working properly, the 02 should cycle from 0 to 1 volts every few seconds.
 
MiniMotoSX said:
Yea it should be oscillating in that range of like .3-.8 but it's just hanging out at .3
Click to expand...

Get a vacuum tester for 20 bucks, see if your engine holds vacuum pressure.

If it loses any pressure over 5 or 10 minutes, check the intake manifold and all vacuum lines for leaks by spraying carb clean around the gaskets and vacuum lines, if there is a bad gasket or line, it will cause the engine to momentarily choke up.

Make sure to check all gaskets in between each plenum of the manifold and all vacuum lines including those used for climate control and evap systems.

If it maintains vacuum pressure monitor the function of the MAF.

Once you have determined that there are not air metering issues the next step is to test fuel delivery.
 
Well last night I got my new O2 sensor in. I took all my plugs out too and they were all drenched in gas. I cleaned em up and put them back in. Then I disconnected the old O2 Sensor and plugged the new one in just to see if it would start up and sure enough fired right up.
 
Great! You didn't do anything with the injectors? Is it running perfect? The 02 sensor code should of cleared up, did the injector code clear up too?
 
Well I put new seals on all of the injectors. It's not running exactly perfect it's still idling around 700-750 RPM's or so. It's still running a check engine light but I haven't put the sensor inside of the pipe yet, I was just holding it while the car was running. Won't I have to reset my computer anyways for the check engine light to shut off and won't it have to go through a full cycle to see if it will come back on or not?
 
any exhaust shop ought to be able to hook you up with a bung intended for this purpose, and its MUCh easier to deal with in my experience ( i tried a nut first) the bung should be like 5$ or so.
 
Yeahh. That what I was figuring except some muffler shops I've talked to said I shouldn't even use an 02 sensor because I don't have any Cats in my exhaust..never heard of that.
 
You must log in or register to reply here.
Back
Top