Running Rich Followed by Dead Upstream O2 (1 Viewer)

[Joe470]

Could use some help on a string of issues and faults I got during my trip this weekend:

• Got to trailhead, and after airing down I noticed the truck had a little bit of a hard time starting. No codes and ran good, so I decided to head up the trail
• It was hooot out (102), and the trail I picked was straight up the mountain (5.5kft climb). About halfway up my coolant hit 226 so I pulled off and let it sit. After pulling off, the idle seemed pretty rough, dipping down to ~500rpm
• I shut the truck off, let it cool for 20 minutes, and then when starting back up it had a very hard time (a good 5 seconds after starting to fire). I decided to call it there and head back down.
• On the way back, I set the following codes:
  • P0172 (Bank1 running too rich)
  • P0175 (Bank2 running too rich)
• After some googling in an autozone parking lot, the most likely culprits seem to be
  • Fuel pressure regulator and/or Vacuum hoses
  • MAF
  • O2 sensors
• The autoparts store had a drop-in MAF for $50 bucks, so I replaced that and cleaned the connection. After clearing the codes it still had a rough time starting but the codes didn't come back.
  • I also pulled and put-back-in just about every fuse in the fuse box
  • I also got my battery checked and it was healthy
• I pulled up the short and long fuel trim on my ultra gauge as I went to a much-easier campsite for the night. Bank 1 and 2 were sitting at approx -20 on the long trim (I think the 'running rich' trips at -30)
• Next morning at camp, I crossed my fingers and toes and turned the truck on. A little rough on the start, but not as bad as yesterday. Still no codes
• On the drive back home, the following two popped up
  • P0134 (Bank 1 Upstream 02 Circuit no Activity Detected)
  • P0154 (Bank 2 Upstream 02 Circuit no Activity Detected)

Now I'm back home and trying to figure out what to do next. It seems like it may have been an O2 issue all along, though when I pulled the MAF during the swap I got a pretty strong gas smell from the intake which is indicative of the fuel pressure regulator. It also seems highly improbably that both O2 sensors would die at the same time. It almost seems like a bad connection or ground somewhere.

If anyone has suggestions where to start I'd appreciate it. I may just start throwing parts at it this week (O2, fuel regulator, and fresh vacuum hoses to start), but I'm not sure that'll fix it.

Video of rough start:

 

[Joe470]

I suspected a bad ground somewhere causing issues, and it sounded like the most common spot was the tailgate harness.

Well............ looks like someone got in there before due to the amount of zip ties. After pulling back the electrical tape, I found that all the connections had been cut and twisted back together!!!!!!!! No caps, no solder, just bare fricken wire lightly twisted and taped! I'm astounded. Probably need to check every other electrical connection that looked like it was tampered with now.

Going to properly fix this harness and then revisit the other issues should they arise, but I'm willing to bet this has something to do with it. Also confirmed no intake leaks, but I don't think that was ever the issue given that it was running rick.

 

[Joe470]

Welp, tailgate harness repaired and now it starts right up. damn electrons

 

[mujtaba117]

Hey man
Thanks for sharing.
I read your comments on the post I have a 2006 Land Cruiser 100 series and it cold starts and runs perfectly fine but takes longer time to start when it’s warm or after a 15 mins or more drive it doesn’t start properly. Starts just like your vehicle in the video.
I need some understanding about what you did?
What do you mean by bad ground?
And also what did your repair exactly at the tailgate harness?
Some clarification or video or picture would be very helpful.
Thanks

 

[Joe470]

Hey man
Thanks for sharing.
I read your comments on the post I have a 2006 Land Cruiser 100 series and it cold starts and runs perfectly fine but takes longer time to start when it’s warm or after a 15 mins or more drive it doesn’t start properly. Starts just like your vehicle in the video.
I need some understanding about what you did?
What do you mean by bad ground?
And also what did your repair exactly at the tailgate harness?
Some clarification or video or picture would be very helpful.
Thanks

So, it think I spoke too soon. I still have the same issue that you have. The grounding issue fixed the open circuit on my 02 sensors, but it still has a rough time starting when it's hot outside, or after restarting 10-20 minutes after stopping.

I found some other threads which seem to suggest the culprit is the fuel pressure regulator. I guess it can leak when going bad and dump fuel into the intake - leading to a difficult start. The reason it causes issues when hot is because tank pressure will build during the day, and the pressure will be relieved at the faulty fuel pressure regulator. Same with letting it sit 20 minutes - the built up pressure in the system as the car is running with vent through that valve. That's the theory anyways.

I ordered an OEM fuel pressure for partsouq but that's weeks away and I need a fix for this weeked. I'm headed to the Auto parts store after work tomorrow and will try and aftermarket swap. It's a very easy part right on top of the passenger side intake.

Will post an update here after that.

 

[Joe470]

I had tracked it down earlier but can't seem to find it again. There was another post describing the same issues when starting hot and that resolution ended up being the charcoal canister. Same exact issue - good when cold but long strat when hot or turning back on ~5-30 mins after running.

In addition to the Fuel Pressure regulator, I'm going to stop by pet smart and grab a bunch of activated charcoal. If fpr does not fix it, I'll drop the canister and re-pack it (some other threads on here showing that procedure). No way I'm dropping $500+ for a plastic bin filled with 5 dollar charcoal

 

[Joe470]

I had tracked it down earlier but can't seem to find it again. There was another post describing the same issues when starting hot and that resolution ended up being the charcoal canister. Same exact issue - good when cold but long strat when hot or turning back on ~5-30 mins after running.

In addition to the Fuel Pressure regulator, I'm going to stop by pet smart and grab a bunch of activated charcoal. If fpr does not fix it, I'll drop the canister and re-pack it (some other threads on here showing that procedure). No way I'm dropping $500+ for a plastic bin filled with 5 dollar charcoal

I should also note, evap code P0441 is pending which leads me to believe this may be the issue

 

[Mike NXP]

Welp, tailgate harness repaired and now it starts right up. damn electrons

=] I didn't want to jinx you but it sounds like your problem is back anyway. Your symptoms didn't point to a bad ground upon first look.

Hope you like to read
>>Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? - https://forum.ih8mud.com/threads/gas-tank-building-excessive-pressure-fuel-smell-dangerous-for-sure-why-does-this-happen.1214321/page-11#post-13251496


When I first read your original post I immediately thought the hot outside air, mixed with way too hot engine coolant temp = fuel issues.


I think you should focus on chasing down fuel issues, like lines getting too hot, boiling in the tank, charcoal canister, etc. I've never heard of anyone repacking these but it sounds like you have seen some forums with info so thats cool.....I don't think your regulator is too blame but who knows, sounds like its getting replaced either way

If you can get the issue to happen again I would do a few things like;
- Open gas tank, listen for venting
- Pull line off charcoal canister, do the same
- Attempt to restart and see if removing the line / opening cap has any effect on the issue and then dive deeper from there.

 

[Joe470]

=] I didn't want to jinx you but it sounds like your problem is back anyway. Your symptoms didn't point to a bad ground upon first look.

Hope you like to read
>>Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? - https://forum.ih8mud.com/threads/gas-tank-building-excessive-pressure-fuel-smell-dangerous-for-sure-why-does-this-happen.1214321/page-11#post-13251496


When I first read your original post I immediately thought the hot outside air, mixed with way too hot engine coolant temp = fuel issues.


I think you should focus on chasing down fuel issues, like lines getting too hot, boiling in the tank, charcoal canister, etc. I've never heard of anyone repacking these but it sounds like you have seen some forums with info so thats cool.....I don't think your regulator is too blame but who knows, sounds like its getting replaced either way

If you can get the issue to happen again I would do a few things like;
- Open gas tank, listen for venting
- Pull line off charcoal canister, do the same
- Attempt to restart and see if removing the line / opening cap has any effect on the issue and then dive deeper from there.

Great ideas, thanks!

I just finished the first little test - left my gas cap loose during work today, and just started up no problem even though it's 100+ degrees out! Good data point. This should let me isolate down to the (suspected) charcoal canister by playing with both the gas cap and canister tube. Maybe I'll skip on that FPR for now

 

[Joe470]

For legal purposes I'm making this post from Florida (something something can't tamper with emissions equipment)

After reading up some more, it sounds like I flooded the Charcoal Canister (with the latter 100 series being more susceptible). Given that the Charcoal Canisters are $500+ new ($900ish for OEM), figured I'd open mine up and replace the charcoal and clean it out.

I've seen two other methods - cut the whole thing in half, or cut a hole in it and stuff it with a funnel. Wasn't a fan of either, and after removing the CC I noticed a seam where it looks like the cover is press fit in. Took a hammer and screwdriver around the outside seal and eventually it popped right off!

From there, dumped the old charcoal and pulled the filters. All filters washed throughouly with soap and water and allowed to dry fully. Filled the thing back up with activated charcoal (from PetSmart fish section). The "lid" popped back into place and I applied a liberal amount of jb plastic weld. Let that fully cure and slapped the CC back in there.

All in all, 2 hour job when accounting for dry times. It really was easy, and total cost around $60 bucks (also replaced all m8 and m6 bolts).

Not going to jinx it yet, but the four test starts I did in the last few hours, it's started right up every time! Tomorrow will be the real rest (super hot tomorrow), and will be in the worst conditions for the issue (hot car and hot air). Will follow up here with how that goes.

Shout-out to Mike NXP for saving me $100 bucks on a FPR

 

[Mike NXP]

For legal purposes I'm making this post from Florida (something something can't tamper with emissions equipment)

After reading up some more, it sounds like I flooded the Charcoal Canister (with the latter 100 series being more susceptible). Given that the Charcoal Canisters are $500+ new ($900ish for OEM), figured I'd open mine up and replace the charcoal and clean it out.

I've seen two other methods - cut the whole thing in half, or cut a hole in it and stuff it with a funnel. Wasn't a fan of either, and after removing the CC I noticed a seam where it looks like the cover is press fit in. Took a hammer and screwdriver around the outside seal and eventually it popped right off!

From there, dumped the old charcoal and pulled the filters. All filters washed throughouly with soap and water and allowed to dry fully. Filled the thing back up with activated charcoal (from PetSmart fish section). The "lid" popped back into place and I applied a liberal amount of jb plastic weld. Let that fully cure and slapped the CC back in there.

All in all, 2 hour job when accounting for dry times. It really was easy, and total cost around $60 bucks (also replaced all m8 and m6 bolts).

Not going to jinx it yet, but the four test starts I did in the last few hours, it's started right up every time! Tomorrow will be the real rest (super hot tomorrow), and will be in the worst conditions for the issue (hot car and hot air). Will follow up here with how that goes.

Shout-out to Mike NXP for saving me $100 bucks on a FPR

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Wow , impressive. I thought you were a bit nutty when you suggested opening and replacing charcoal.....i suspect others will be interested in trying this .


True test will be some wheeling on a hot day with lots of climbing like your original issue was caused by .


Nice work

 

[Joe470]

Nice and hot today. Multiple starts with no issues where as before it would be 10+ seconds cranking. Dare I say she's fixed!

I suspect I flooded the CC after topping off my tank and driving over the mountains to get to Logan UT. Was about 102 at the time doing a hill climb with a completely full tank. Time to add a heat shield and only fill to 3/4 tank in the summers.