Hello,

Need some input before I remove the O2 sensors out of my 1998 Trooper. I checked the upstream location of the 3 wire sensor and it has room to be removed without disassembling anything else.

The downstream 4 wire sensor on the other hand looks like it has room to be removed but am having second thoughts. There''s a bar the is blocking it for full access. I was looking for advice if I need that bar removed to remove the O2 sensor (4wire).

Thanks for any info.

 

Are you getting CEL codes for the after cat sensors? If not, dont worry about replacing them. All they do is check if the cat converter is working. The ones before the cat are the ones the ECU uses for fuel trim.

 

Hi Gizmo...No Error codes detected at all.
I''m failing smog on the HC side @ IDLE:
MAX is 100, Measured 175. Hc passed at 2500 RPMm MAX is 170, Measured 30.

A bit of history...it failed NOx 3 times already.
I removed my intake manifolds, removed the carbon deposits as much as possible, soaked it in gasoline for a few hours for thorough cleaning, new gaskets installed, no leak on vacuum lines, new spark plugs , new EGR valve and no DTCs detected by the scanner.

Everything seems to be spic and span, I''ve been searching all over the net, and now the Hc is the new problem.

High HC= incomplete combustion

-bad ignition, coil, plugs, wires, cap, rotor <<<COIL PACKs are good.
-stuck EGR <<<N/A new EGR installed



-low compression <<<will need to check

-over advanced timing <<<need to check..although the engine''s rpm at idle does not show any sign of misfiring, even when ran. no hesitation experienced.


My next step is replacing O2 sensors since I believe they are original ones (180K mileage on her at this point) and may be past its prime, hoping this will help pass smog test.

If not, CAT replacement is next, if $$ is available....although I may just donate it and get a grand for it.

Any other advise is really appreciated.

Thanks Giz