O2 Sensor?

[Q45Viper]

I posted a few weeks ago about a slight miss or stumble I had on light acceleration passing through 40-45 mph. One of the responses I got was a possible bad O2 sensor, I wanted to live with it a little bit as I played with low speed in third instead of drive to eliminate the transmission. I think I did. Plus I just flunked emissions test in Maryland and the brain surgeons administering the test told me it's probably the O2 sensor. That's fine, more info for me for $14 and I got till Nov. 4th to fix or spend $450 to document I tried to fix it. The last part will be easy, right? anyway, it flunked Oxides of nitrogen, NOx. supposed to be 2.3000GPM and it did 3.5902GPM..... HC fine at 0.5188GPM and CO fine at 3.1656GPM, CO2 as read at 547.3837 is a non pass or fail item.QUESTION....Does this tell me I DO have an O2 sensor problem or sonething else....and if I do have an O2 sensor problem what else should I have done at the same time, is this a plenum pull to get to the sensor? that means do the cleaning and replace ALL hoses right? How about the injectors underneath? Car is due in on Wed. to the guys who did my chains, I have read enough to know I don't wanna go underneath this plenum twice. Advice?92 Q Federal with traction 130k Guides, transmission, air, sunroof and lots else done.Thanks, Lee

[Q451990]

No need to pull anything but the bottom shield and the O2 sensors to replace O2 sensors. Q45Tech should be along soon to tell you what those readings point toward... I've never had a smog test here in SC (thank goodness!)

Heath

[DAEDALUS]

There are a few possibilities. Another high NOx thread:

http://www.nicoclub.com/forums...19626

[Q45Viper]

Sooooo, O2 sensor or EGR?? And no plenum removal?? This could be good news. Confirmation, Q45 Tech?

[Q45tech]

Nox is always EGR dirt and diminished flow if the AF ratio is correct 14.7 [as set by proper O2 sensor cycling].At 12 years and 130k you need both attended to.

[wamQ45]

Funny thing...I went through emissions last Thursday and failed the inspection portion of IM147 (what ever the hell that is). I had two vacume lines disconnected and they mad me re-connect and re-test, no real problem... My Q has 177K on the clock and here are my readings. Before AfterHydrocarbons 0.29 0.09Carbon Monoxide 5.34 2.52Oxides of Nitrogen 0.97 0.86

I have done the under the plenum, O2s and such but not the EGR. I do still have sluggishness when warmed. EGR???

[Q45tech]

The 94 and later Q engines have a temperature sensor on EGR that tell the ecu BETTER how to apply how much EGR.

The EGR plug up varies a lot from vehicle to vehicle, driving style and amount of warm cruise.........the better controlled the mixture [leaner it is] [good O2 sensors] the less pure carbon [more carbon dioxide gas] is in the exhaust so less solids to flow back into plenum.

[Q45Viper]

Update... O2 sensor is bad, also throwing codes showing knock sensor problem also. THAT'S a BIG plenum pull, right? Could not the knock sensor be reacting to the bad O2 sensor? Anyway they are replacing the O2 sensor and will clear the codes to determine whether the knock sensor is bad. Still leaves me a little confused regarding the EGR issue, could I be off the hook with the EGR issue? I don't think the O2 sensor has been bad very long. Is the EGR issue a big deal money wise? Maybe I shouild just tell them to check that out too? I AM planning on pulling the plenum and replacing everything, I just hoped to do it in an organized, planned, budgeted way. Lee

[90Q45blue]

You don't need a NEW EGR system. You just need to have your old one cleaned. The only thing you'll need to replace is the EGR Valve Gasket which is less than $4 from Joe at Scottsdale. If you have the plenum off, it is wise to clean your EGR tube.

nick

[Q45Viper]

Believe me if the plenum comes off EVERYTHING will be done, I think you just answered the question I did not ask very well...in order to get at the EGR system the plenum has to be off?

[Q45tech]

No you can clean the EGR without removing the plenum with a rotor router.......something like a strong metal cable and a drill.

[Q45Viper]

Thanks

[wamQ45]

You know what would be an interesting or category, emissions. An entire area to post emission readings for comparison. I mean I would like to know how my reading compare to the others in AZ that are subject to IM147. Also, it would be interesting to see the other states that are subject to this same method of testing.

[QShip]

O2 Sensors NGK OE identical O2 sensor 24142 FC $49.85 NGK OE identical O2 sensor 24157 FC $59.85 NGK Universal oxygen sensor 21026 FC $44.85

This is from sparkplugs.com. Which is the correct sensor to order?

[90Q45blue]

24142 is the one you should be ordering but you need to order 2 of them.

Nick

[QShip]

Thank You!

[wamQ45]

Just be prepared to do some cutting and soldering......The leads I received were verrrry long.

[DAEDALUS]

The 24142 leads are the shorter ones, 18" I think.

[Q45Viper]

Update... The O2 sensors were shot, you guys called it as usual. Now here's the confusing part....After putting the new sensors on and clearing the codes, the car is still throwing codes for the knock sensor, but no lights, there were no lights for the O2 sensor either. the tech. has advised me to ignore it untill I pull the plenum and do everything else under there. His analysis is...I run Sunoco 94 only and the knock sensor is only to protect the engine from detonation under adverse conditions I am not likely to see. He believes I can buy some time here to put all the parts together to do the whole underplenum thing including the knock sensor in a month or two. Your opinions guys?

[Q45tech]

The ecu has a timer to check for O2 sensor cross counts if there is at least 1-2 cross counts in 2 minutes the ecu may not light the MIL light.........Ideally one would want 60-100 cross counts at 2,000 rpm after warm up.

The knock sensor never lights the MIL light, it is assummed that the severe sluggish behavior of having the timing retarded is enough warning or the every 90 day Consult check you do when you come in for an oil change...........unfortunately even dealers have non tecks do the changes and Consult testing is not free like it use to be for new buyers under warranty.

Failed KS are not benign as the fail safe program [ignition advance reduction] tends to increase the coolant temperature at cruise.

Hopefully Sunoco 94 is at least a real 87 and has a decent motor octane rating........it should be decent in the Summer refinery runs by now.

I agree that a month probably won't hurt anything, now if your coolant goes above 195F there will be additional timing reduction!