In December I experienced a flashing check engine light while driving. I replaced all 4 O2 sensors and those seemed to smooth everything out.
That thread: https://wranglertjforum.com/threads/check-engine-light-flashed-while-driving.67087/
Since then I've experienced two instances of hesitation during acceleration; the first one was driving at about 55 mph and I began to accelerate climbing a hill. It was like I had a governor on the vehicle. I did a code check with the key and ignition; no stored codes. I decided to buy a Bosch fuel pump/module because it seemed like it was a fuel-related issue. The pump arrived and I continued to drive, running the fuel to almost empty in preparation for the pump change.
Before I was able to change the pump, I experienced the second hesitation. This time it was while accelerating through a flat turn. I also got the flashing CEL. I could replicate the hesitation this time, by accelerating over 3,000 rpm and each time it felt like it was starving/choking out. When I checked the code (both key/ignition and with a scanner) I now had code P0431.
The next day did some diagnostics with my OBD scanner. I checked the voltages of all the O2 sensors, thinking maybe one was bad. All 4 were working but both sensor 2 sensors reporting wildly fluctuating voltages. My thought process was, if the catalytic converters were functioning as intended, the post-cat sensor voltage should be like .5 V or something close. My readings were all over the map, swinging from numbers like .015 then .70, then .40, then .30, etc. and they changed rapidly. I turned the engine off, let it cool, and tightened up the bolts where the pre-cats connect to the manifold. If those were loose then air being sucked in could skew those numbers. I ran the scanner on the sensors again, no change. Now I started thinking, this is probably going to be expensive.
While letting the vehicle idle I kept hearing this intermittent, deep rattle. I thought it was the shift fork so I pressed in the clutch. Nope. The rattle was still there. It sounded like it was either under the engine or low on the left side of the engine so I broke out the stethoscope and prodded around. All the engine's moving bits sounded like they were moving as they should. Then I checked the pre-cats. No mistaking that (or the exhaust) was the area of the noise.
I checked for similar stories here and saw a post from @DropTopDon. His video is very similar to the rattle/rumble I'm hearing. https://wranglertjforum.com/threads/is-my-catalytic-converter-about-to-shit-itself.63293/
So it seems like what I've been experiencing is clogged/failing catalytic converters and the vehicle is choking out or the computer is unable to adjust fuel trim to keep things running smooth during acceleration. Or some combination or both.
Initially I was just going to do the fuel pump and then check the sensor performance; however, the rattling tells me I should probably start with the catalytic converters and then do the fuel pump.
Does that sound like I'm on the right track?
That thread: https://wranglertjforum.com/threads/check-engine-light-flashed-while-driving.67087/
Since then I've experienced two instances of hesitation during acceleration; the first one was driving at about 55 mph and I began to accelerate climbing a hill. It was like I had a governor on the vehicle. I did a code check with the key and ignition; no stored codes. I decided to buy a Bosch fuel pump/module because it seemed like it was a fuel-related issue. The pump arrived and I continued to drive, running the fuel to almost empty in preparation for the pump change.
Before I was able to change the pump, I experienced the second hesitation. This time it was while accelerating through a flat turn. I also got the flashing CEL. I could replicate the hesitation this time, by accelerating over 3,000 rpm and each time it felt like it was starving/choking out. When I checked the code (both key/ignition and with a scanner) I now had code P0431.
The next day did some diagnostics with my OBD scanner. I checked the voltages of all the O2 sensors, thinking maybe one was bad. All 4 were working but both sensor 2 sensors reporting wildly fluctuating voltages. My thought process was, if the catalytic converters were functioning as intended, the post-cat sensor voltage should be like .5 V or something close. My readings were all over the map, swinging from numbers like .015 then .70, then .40, then .30, etc. and they changed rapidly. I turned the engine off, let it cool, and tightened up the bolts where the pre-cats connect to the manifold. If those were loose then air being sucked in could skew those numbers. I ran the scanner on the sensors again, no change. Now I started thinking, this is probably going to be expensive.
While letting the vehicle idle I kept hearing this intermittent, deep rattle. I thought it was the shift fork so I pressed in the clutch. Nope. The rattle was still there. It sounded like it was either under the engine or low on the left side of the engine so I broke out the stethoscope and prodded around. All the engine's moving bits sounded like they were moving as they should. Then I checked the pre-cats. No mistaking that (or the exhaust) was the area of the noise.
I checked for similar stories here and saw a post from @DropTopDon. His video is very similar to the rattle/rumble I'm hearing. https://wranglertjforum.com/threads/is-my-catalytic-converter-about-to-shit-itself.63293/
So it seems like what I've been experiencing is clogged/failing catalytic converters and the vehicle is choking out or the computer is unable to adjust fuel trim to keep things running smooth during acceleration. Or some combination or both.
Initially I was just going to do the fuel pump and then check the sensor performance; however, the rattling tells me I should probably start with the catalytic converters and then do the fuel pump.
Does that sound like I'm on the right track?