Hi all, I'm back in this part even though I don't own my 3rd gen anymore. Just got done with a road trip to Hot Springs, Arkansas for a wheeling trip up there with me and my 2 brothers. I hauled my XJ with my 06 4Runner and my brother followed with his new to him 96 4runner (my old one). Way there went great and both vehicles did fantastic off road and took a hell of a beating during the process so I was impressed. Fast forward to going home, things were not so smooth. About 2 hours away from home, I see my brother put on his hazards and pulling to side of the freeway. Shit. He said that it started shifting really weird (like downshifting going downhill), surging, loss of power, then died as he was coming to a stop. I could smell a strong sulfur smell so I thought the cat gave up the ghost and was restricting the exhaust majorly. So we removed the upstream o2 with it still plugged in and attempted to start it. It cranked then sputtered and ran for like a second then died again. Tried again. Cranking but nothing else. Few minutes later after looking everything over I heard a fast clicking under the throttle body with the key on, but stopped when key was off. Had key on and unplugged IAC, boom it stopped. Okay, so it's the IAC. Fair enough, it's original. So we run to the nearest part store 30 miles away to get a new one. Battery was disco during all of this btw. Plug battery back in once new IAC was installed, turn key and crank crank crank sputter then nothing. What the hell! The IAC was clicking just like the old one too. I could smell a ton of fuel in the engine area too everytime we cranked it. I called it a night and wanted to get the hell home so I let my brother drive the XJ back home and pull the 4runner up the trailer with the winch to get it home.

A good night sleep later, we decide to take another crank at diagnosing the runner. Tested for spark, it's getting it. Defintley getting fuel as I can smell it strong. I start thinking maybe its the ECU. Weird shifting, IAC clicking fast, ton of fuel. For shits and grins, I decided to disco fuel pump connector and spray starting fluid directly into throttle body while he opened throttle and cranked. After a bit of starter fluid, it runs for a little bit! Sounded like a lawnmower engine with o2 removed though lol. So I've come to the conclusion that the ECU is sending a shit ton of fuel and flooding the engine. Is my diag pretty sound in thinking its the ECU that's shit the bed? I suppose it could also be a stuck fuel pressure regulator.

Pull the vacuum line to the FPR and see if spits or even smells like fuel first. Got a banjo bolt adapter to measure the pressure.?

You do have a scanner with live data correct? I’d be curious to see what the O2 data looks like.

Is the money light on?

I'll be sure to check the FPR tomorrow if I get a chance. I do have techstream I need to hook up to it. No CEL, and no pending codes either according to scangauge. This thing never did like to throw codes for obvious issues lol. And no, I do not have the banjo adapter.

It sounds to me like something outright failed, like a sensor. MAF or crank possibly?

Any DIY work done on it recently?

I don’t know if any of those would be bad or not cause the engine did run with the fuel pump disco and me manually putting starter fluid into it. I’ll still be sure to check the resistance of the MAF to make sure though. No DIY work done recently. It was running fine then boom nothing

I was also thinking possibly the TPS since your bro said it felt like it was downshifting weird, but it wouldn’t explain the no start.

Main relay good? Unless the Texas heat really got to the ECU I would say it is something else but electronic based.

Enjoying the 2UZ?

I think you're on the right track with ECU. It happens.

The weird shifting is a big clue too.

Ya I don’t think it would be the TPS. Which main relay? Also I forgot to mention that I did pull the ECU and it looked like it’s been sitting in flood water or something way before I owned it. All rusted and corroded looking. In fact, the entire core support behind the dash is like this.

Yeah the power/torque of this thing is amazing compared to the 5VZ. I’m asmazed how well it pulls a 6k+ load.

That could be a problem. I guess I would start by making sure you have power to the ECU. As you say it might have just been a matter of time.

Let us know how it goes.

Just thought I would update this for others having a similar problem to mine. The "new" ECU from eBay fixed the issue entirely. And my brother is reporting better fuel economy as well.

I guess you haven’t opened up the old one then? Curious how it could have been flooded.

Regardless, good to hear.