hakukamana

Hey Pete, I am an old guy what does that mean exactly. I have an active posting in tech and modifications, and I took some videos of my scanner and the readings, I had to trim them down to fit the 9.77MB threshold but I posted one, then I thought I could post the other but it wouldn't let me. I had a couple of responses on the post then tried again to post it and it worked. Does that answer your question? I have the video files on my computer.

The failures of the O2s we're open loop, Lean, not rich, and the voltages were way off, not swinging from low to high, it was like the heater fried, and then the rest of the sensor just went wacko. I just would not think (3) bad O2 sensors. But each one that failed, initially worked fine for a couple of days. Then just stopped working correctly. The latest one was installed today, and it's working

I am monitoring the data off the scanner, MT2500. Short of using a Lazer temp gun, which I have, how else would I verify temperature?

I run a 195 thermostat

Coolant temp switch on the block, operating temperature readings are correct, from cold start up to full operating temperature. I can monitor the temperature as the truck heats up after the thermostat opens runs about 187 at idle.

Interesting so what drives the STFT, so that it would reach a limit boundry? Is it normal for STFT to stay within the 0 to 255 limits. I think LTFT is at 128 based on the last operating temperature scan. If the STFT reaches the 0/255 limits what happens to LTFT?

Are you saying it could take 3-4 days to trip the LTFT? What triggers the LTFT to change? Driving conditions?

This is number (3), for O2 sensors in less than 10 days

Its really hard to get a video squeezed into 9.77MB's

This is at 195 * operating temp 195_Operating_temp.mp4

The operating temp scan has the O2 voltages down below 1 and then moving up as high as the 4 +while thats going on its switching from rich to lean, pulse width is in the 5's the new O2 is working as it should but so did the NTK that I put in a week ago. Then something happened? It froze in open loop/lean and voltages were stuck in the 3V range. Even when it warmed up nothing changed. Its a weird issue, new runs and operates fine, a couple of days of driving and not more than 80 miles, bang its DOA. Stick a new one in works like a champ, drive a few days and again its dust. I don't think the sensors are dying on their own, I am just wondering if its something in the O2 circuit or the ECU reference signals.

Ohm it's moving from Rich to Lean on the scanner, that was cold start scan. It was in closed loop. The pulse width was high, at cold start, then at operating temperature drops down to the 5.? Range. Short term ft was in the 70s, long term was fixed at 128

when it says max size 9.77Mb is that for the entire post or per individual response or post? I trimmed down (2) videos under the 9.77 Mb limit, but would only allow me to post one. Went down to reply in the topic and would not let me down load another 9.77Mb video. Both videos were 7.5mb in size

It appears that I can't upload the operating temps video

My failure was open/lean. You are correct Eagle FSM default is open/rich. Installed a new Bosch O2, works just like its supposed to, enclosed are two video's start up, and operating temp. We will see how long this one lasts? Start_Up.mp4

DMM battery is good Fluke 88. Put in a new 9V just for kicks. Battery voltage is 12.48 at the terminals. KOEO battery power to the O2 harness treminal A, 11.88V again ground to the sensor circuit ground point, at the dipstick. Initial O2 readings with new O2 STFT and LTFT were moving and adjusting, after the failure LTFT fixed, STFT can't remember. I just got another brand new Bosch O2, ready to install. Will give you an update when I scan.

Key on engine off, heater voltage circuit is reading 11.88 volts. Ground for the DMM was connected to the sensor ground circuit at the dipstick block bolt. Gounding point is clean and shiny. Ohms for the heater circuit on the O2 sensor were reading 19.2 between A & B which is not in the spec range. The FSM indicates 5 to 7 ohms if not replace the sensor. which I have done now twice. The new sensors work correctly when initially installed, but over the course of a few days, they seem to be failing, that is the question??

OK, as the title indicates, I have been experiencing multiple O2 failures. I have checked power, signal voltage, ground resistance. Checked relay power, I had a bad O2 sensor would not go into closed loop and defaulted to open loop, lean mixture. This is the default mode for the ECU. Purchased a new NTK O2 sensor, installed it, perfect, works just like it is supposed to work, everything is working correctly, "WRONG", 4 days. Hooked the scanner up looking at live data, initially moving from open to closed loop at start up, but no switching from lean to rich, at operating temp, finally just sits there at open loop, lean again. OK, so now I buy a new Bosch O2 sensor, again everything is as it should be at start up, open loop switching from lean to rich goes into closed loop, mixture switching continues to occur, voltages are working in range, pulse widths are correct, short term fuel trims are adjusting. 3 days later its dead again. Scanner is a MT 2500 so I am reading live data. The only thing I can think of is the sensors are being contaminated by the combustion process and fouling or shorting out the sensors. Anyone have any thoughts?????

Your YJ if its an automatic is probably a 32RH. No electronics, a 3speed, and all hydraulic. The YJ transfer case is probably a NP231J. The MJ automatics are AW4's, also there is a difference between the 2wd auto and the 4wd auto, transfer case could also be a NP242 in the MJ. The AW4's also have a seperate computer? (sort of computer) that works in conjunction with the Renix computer and the TPS for the automatic. Easiest swap is an MJ 4wd automatic, or a Cherokee 4wd automatic, still have to do an axle swap and a bunch of other things to have a 4wd auto MJ

I'm in if you can get it to Hawaii in one piece. Gray Interior

What Control unit do you have ? Heater or AC/Heater? You do have a defrost door on the heater core housing, no vacuum=wide open. The panel door is closed, and the Floor Door is closed, vacuum. Green plastic line to dashpot for defroster door, from #9 on heater control switch, the heater controls also need to be in the heat mode. The heater controls are all rubber connectors and plastic lines to the various dash pots and the heater control switch.

Just a thought, the electrical load from the vehicle will pull the voltage down. It should not pull it down into the red, but lights, blower motor, reverse lights(???) I don't know why?, if you have a short, or a severe load on the electrical circuits in the truck it will pull the voltage meter down from the normal 14 position. The more circuits that are in use the larger the load on the charging system and the battery.

Check your instrument cluster ground. Is your alternator case grounded? Is your alternator plug a two wire or a three wire? The two wire is usually one wire triggers the voltage guage, the other is for an AC feed. Have you checked your battery for voltage while the truck is running? Should be 14.+ Do it with a DVOM The last thing I would say is I have a 93' YJ and had a similar issue, it was the charging circuit in the ECU, sent it off to have the circuit rebuilt or so the rebuilder claimed, got it back hooked it up and "POOF" in a cloud of smoke the ECU fried. If you find it is the ECU don't waste your money on trying to have it rebuilt. Find a similar year, engine, and transmission combination from a donor and replace it. It will be cheaper in the long run.

Aren't those seats and the molded headrests from the 88' and earlier model years?

If you had access to a Snap On Modis MT2500 scanner, it would help a bit to see the engine soundness. You would also need the correct adapter and the chips for the scanner. These trucks don't have a memory, they are live data only critters. But having said that it will give you a look, a rpms, engine temps, pulse width, timing, TPS voltages, charging ect. Check the steering, loose track bar, drag link, ect. Listen and look for sounds out of the rear axle, see if its got a 44(Dana) might be an Eliminator?