2G 02 Sensor stop reading

my dreamt dsm · Aug 29, 2014

My car is being a little b**** lately. Compression and boost leaks are okay, vacuum is okay.
Code P0170 and 90170p popped up. That is fuel trim malfunction having to due with maf, injectors, o2 sensors. Those are all replaced.
Another code 90125, that is coolant temp sensor. Probably causing car to run close loop.
So car is bogging and acting really really sluggish and heavy. I took it to a local shop. their project car is an evo 9 and closest shop that touches Mitsubishi. The tech pulled out a expensive looking tool/ scanner to read the codes. As he showed me the code. The o2 sensor read for a few seconds and stop. The wave spike of the 02 sensor went blank and the car started the weird idle again.

Why would the 02 sensor stop reading? Bad ecu since all things have been done and nothing works.

Post 5 and 6. 6 being exactly how my car is.
http://www.dsmtalk.com/forums/showthread.php?t=28069

Car spec:
98 gst, 5 spd 134k miles
kn fipk, hks exhaust, test pipe, fp manifold, evo 3 16g, 10psi, injen intake, intercooler,

crimsondragon · Aug 30, 2014

Could be faulty wiring. Check for continuity from the front O2 to the ecu. Those wires are shielded and if there's a break, it could ground out on the shielding. It would also most likely fry the drivers in the ecu. It would explain the multiple faults.

my dreamt dsm · Sep 14, 2014

More clues but I can not pin point the problem. on the dsmtalk link hoteclipsegsx seems right but I'm looking for what sensors are involved. Any clues?
http://www.dsmtuners.com/threads/2500-rpm-knock.279651/
http://www.dsmtalk.com/forums/showthread.php?t=213596

crimsondragon · Sep 14, 2014

Do you have a logger or a scan tool? I'd check your ECU parameters. Look at the coolant temperature specifically. I can't remember if on Link the O2 sensor will not read until it's fully warmed up or the car is in closed loop. I want to say that it should still show voltage cycling on the logs but I could be wrong.

thejollyrancher · Sep 14, 2014

After you replaced all the mentioned sensors, did the code go away?

my dreamt dsm · Sep 14, 2014

I haven't replaced the injectors yet. I'm going to test them tomorrow with the screw driver trick and ohm reading.
I've been doing research and it comes down to ecu trying to compensate for being to lean. Maybe one of my injector is not firing or something.
I know it's not the p0125 code, that' is just being thrown because the 90170 is shown. It's stuck in loop. I know because my temp gauge gets hot like usual.

Also car knocks (detonate) right at 2500rpm after the car warms up to temp and in every gear 1-5. For example im on the freeway and as rpm climbs up and reaches 2500rpm (about 60mph) car knocks, like 40-50 counts. As soon as I past 2500 rpm to like 3000rpm (70mph) knock goes away. But if I have to slow down again to like 2500 rpm (60 or so mph) car will knock again as I climb up to speed (70 mph)

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2G 02 Sensor stop reading

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