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California Smog Test - Spectacular Fail...!

NeXJ

NAXJA Forum User
Location
Los Angeles
I'm trying to get my 92 XJ back on the road after having sat for about a year and a half since it failed smog last time (that's partly why it's been sitting so long!). Last year's fail was supposedly due to a dead cylinder, which has now been repaired.

At any rate - last year I replaced all the plugs, wires, new rotor and cap, all the usual stuff - including a new TPS since the last one died, new aftermarket O2 sensor if I recall correctly. At the time, only the NOx was high.

Before I go on - I SHOULD mention that YES - I've read some of the other smog posts so I'm familiar to some degree with the issues - but this seemed a weird case - so I thought I should post it.

Today - I did another smog and got the following results:

15MPH %CO2=14.2 %O2=0.0 HC=131 (max=86) CO=1.02 (max=0.51) NO=1245 (max=711)

25MPH %CO2=14.5 %O2=0.0 HC=102 (max=72) CO=.85 (max=0.65) NO=892 (max=613)

The smog guy told me that it was probably largely due to buying the 'aftermarket' O2 sensor - and that the OEM sensor should give me improved results and that I should get a new coolant temp sensor as well, and change out the custom headers, cat and exhaust (though I passed with those four years ago when I did it last), among other things. IF I choose to get the new O2 sensor - my conundrum is whether I should get the 92 version or the 97 version. The computers are different. It seems (maybe) I should get the 92 since my computer is a 92 (?).

But a likely culprit, it seems to me, might be that I did the test on the residual (less than a gallon) of gas that was 1.5 years old (???). I'm not sure if I did the oil change last time.

92 XJ Sport with 1998 HO 4.0L
Borla Headers high flow everything (incl cat, exhaust etc etc)

IDEAS??? SUGGESTIONS???

I thought maybe if I change out the oil and the gas and or run something special in the gas (alcohol or acetone) I might get the numbers down...(??)
 
Well you could leave California, come to Tennessee where we have no safety or emission tests at all. Plus save a ton of money by just leaving that place. Just kidding though, I really hope someone can help you with that, no XJ should just be sitting there.
 
ha! believe me - it's a tempting thought lately...! kinda hard to leave without getting it legally running though!!!
 
For starters:
Change oil/oil filter
Get the 02 sensor that goes with your vehicle.
Fill your tank and run a can of G2P ("Guaranteed to Pass"), follow instructions.
Get a NEW gas cap.
Fix/Replace all vacuum lines.

Run it in to the smog place hot (at temp), after some highway driving.
 
Get the O2 sensor meant to go with the computer - so a 92 O2 sensor. Stay away from no-name and fits-everything, Bosch pretty much invented the O2 sensor so I stick with them (and I'm pretty sure the dealership sells Bosch.)

Looks like you're running rich; there is no O2 left at all in your exhaust gases and the HC is over the limit.
 
While JoJoDaKilla has the best idea, I would do what ParadiseXJ and Kastein have suggested.

Also, if you put in some kind of circus plugs, get rid of them. Another point, Nox indicates you are running hot cylinder temperatures--if you have a 97 head use 97 plugs, 92 head use 92 plugs. Plain Jane Champions or NGK V-Fire.
 
Definitely run all of the old fuel out. I would say easily a tank or 2. Some seafoam or MMO in the tank should help also.
 
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