Replacing o2 sensors in a 1990 Q

[mattd1979]

Yeah, I guess I'll have to try the same and put a load on it by cruising at 2000rpm and then do the acceleration tests. I've only been getting measurements by revving it to 2000 rpm and so on with it in park. It is easier to watch the live readings that way. Now if I just have to get the other sensor out. As far as how it runs. I haven't had any noticeable problems and there is not check engine light. I was just monitoring all of the gauges one day using ECUTalk and noticed that the o2 gauges weren't reacting like I have seen other o2 sensors react in other makes like Ford and Chevy by switching from on to off or high to low volts in a pulse like pattern. The ECU doesn't even throw codes for the sensor when they are both disconnected.
I thought that was odd. I've been getting around 18 MPG city/highway. I've been monitoring my gas mileage ever since I got the car. I have another MAF on the way because the other started acting up and I have already opened it up and worked on the connectors a few months back but it has started acting up again.

[Infinitiguy19]

Here are some more readings I took today:

http://spreadsheets.google.com/ccc?key= ... HUmc&hl=en

http://spreadsheets.google.com/ccc?key= ... tZXc&hl=en

http://spreadsheets.google.com/ccc?key= ... tcWc&hl=en

http://spreadsheets.google.com/ccc?key= ... NZlE&hl=en

http://spreadsheets.google.com/ccc?key= ... MUUE&hl=en

http://spreadsheets.google.com/ccc?key= ... 1anc&hl=en

http://spreadsheets.google.com/ccc?key= ... FR2c&hl=en

I borrowed a laptop and installed ECU talk...To my surprise guess what codes showed up, Code 33 and 53 (Both O2 sensors).

The one O2 sensor did swing from high to low (not sure every when though) when fully warmed up at 2000 RPM's. I am going to guess it was about 5 times in 10 seconds. I will do some more testing tomorrow.

[mattd1979]

Unfortunately I can't view those spreadsheets that you posted because it says that I do not have permission.
For some reason as I mentioned above in my last post, my ECU doesn't even throw a code when the sensors are disconnected.
Thanks for what you have posted so far. So you said that the one sensor did swing from high to low around 5 times at 2000rpm?

[Infinitiguy19]

Links fixed!

And yes that one sensor did swing from high to low 5 times maybe more.

[lino]

Has anybody here replaced the o2 sensors in they're Qs? If so, were you able to remove them on the engine or did you have to remove the headers first?

Matt

Did you end up replacing yours?

[OwnerCS]

I sure like all of the information shared in this thread.

Is it common for O2 sensors to start failing, thus producing a fuel/air mixture that is too rich or in some cases too lean -- then the wrong mixture then leads to the car misfiring without a check engine light being triggered or error code that makes it difficult to find the culprit?
Should O2 sensors be replaced or removed and physically inspected every 100,000 miles as a best maintenance practice because:

1) A failing O2 sensor can be hard to identify, and
2) O2 sensors should be replaced or physically removed and inspected (threads maint.) at 100,000 mile intervals to prevent a thread locking problem from occurring that hinders replacement when the sensors ultimately fail?

I found the following information about O2 sensors.

http://www.tomorrowstechnician.com/Arti ... wered.aspx

[Q451990]

The sensors tend to get sluggish and cause a rich mixture. The danger is melting the internals of your pre-cats. I think it's best to just replace them every 80-100K as maintenence.

Heath

[OwnerCS]

The sensors tend to get sluggish and cause a rich mixture. The danger is melting the internals of your pre-cats. I think it's best to just replace them every 80-100K as maintenence.

Heath

Thanks for the info!

Here's another item for my restoration project. :-)

[mattd1979]

Has anybody here replaced the o2 sensors in they're Qs? If so, were you able to remove them on the engine or did you have to remove the headers first?

Matt

Did you end up replacing yours?

Yes I did finally get both replaced. But it didn't do any good. I was still getting the same readings. In the end, it was my NICO ECU. Apparently when set to power level 3, it ignores the sensors.