Hey all,

Last week after getting back from a 6 hour drive, I was sitting in the car wash and the 4runner just died. It wouldn't start the first time I tried, and then it did. CEL and then VCS trac lights came on.

Got home and pulled codes and got:

Pulled the MAF sensor and cleaned it using the special spray. No dice. Cleaned the throttle body. No dice.

Ordered a new OEM MAF sensor and just got it today (after waiting 5 days for it to arrive). Threw it in, and tried clearing the codes. No change.

The truck is stuck in limp mode (won't go above 3,000RPM), and every time I clear the codes the truck dies again. It's driveable under 65 otherwise, as it just takes two times to start, no more, no less.

What the heck is going on!? Do I need to reset the ECU again? I'm writing this as the battery is sitting disconnected, so I'm going to head out there after I submit this and try it all again. So bummed.

Bump? No ones had MAF issues like this?

Cloged up air filter?
Sound like something got wet in the carwash?

Yeah I tore everything apart from the air filter box onward to the throttle body. Nothing is off.

I’m kind of wondering if the wire harness got messed up but I don’t know how to check that with an ohm meter.

Any past rodent issues? Could the ECU connection have gotten wet? Just reaching here, but maybe a crazy idea will give you one. Definitely curious. I hope you get it sorted out soon.

Nah nothing to speak of. It happened in a car wash so I’m guessing something got wet that wasn’t supposed to?

The new MAF is a dealer OEM? or online purchase? I keep hearing stories of counterfeit parts online. Hope it's something simple and not too aggravating.

It’s dealer OEM. Sigh. So lost. I hate to admit defeat but it’s going to the shop.

Take a few minutes and look for a very large vacuum leak. When unmetered air gets into the engine it can throw a MAF code.

Yeah, I checked and didn't see anything.

I pulled a couple more codes after driving it for a bit related to the O2 sensor:

Part of me thinks (hopes) that's just a symptom of whatever is throwing the MAF off. Anyway, I dropped it off at the shop since I'm at a loss, so we'll see.

Sigh.

How did you check? Just looked around the engine compartment? If so that's not going to do it.

I mean, I don't have a vacuum gauge pump, but I checked all of the vacuum hoses for obvious signs of breakage, etc., and used the carb cleaner trick around the usual suspects and listened for the engine idle change.

I didn't check my headers though, and I wouldn't be surprised if there was a shoddy weld on the DT headers that gave out.

We'll see what the shop says since they likely have smoke machine. I'm sure it is a vacuum leak somewhere, just curious where since it's beyond my abilities at this point.

My go-to shop couldn't fix it. He thinks it's something going on with the computer. Showed me a print out of the MAF airflow rate is just flatlined at .23 g/s whether it's being given throttle or not. He tried swapping another MAF but same results. He didn't see any vacuum leaks either. He said replacing the computer might be the fix, but he can't do that since he doesn't have a way of programming it. That sounds expensive as hell.

Dealership doesn't have openings until the 16th, so I'm taking it to another place in the mean-time to see what they think.

FML.

@atalarico Check this guy out from NZ. He is a little hard to understand but knows the UZ platform better than anyone. He just went through the wire loom on a 2UZ in this video. He might be able to shed some light, because he is an expert at ECU swaps. One thing I hear is the security key code is a stumbling block for this. Not sure it affects the older UZs like ours. He shares a wealth of knowledge and there may be something in his videos that might help and he is good at responding to comments in his vids. Good Luck!!
CartuneNZ You Tube

Check your fuses, especially the ones labeled EFI 1 and EFI 2, and A/F Heater. Because this problem onset after a car wash, it's possible water got into a connector and shorted a power circuit to ground.

And by check them, I mean physically remove them and examine the fusible element, then probe them with a meter to verify continuity (infinity resistance reading).

If there's any doubt that each fuse is good, replace it.

If the problem continues, disconnect your battery negative and then remove & inspect each connector on the ECM. Look for corrosion, moisture, bent pins. Spray out the connectors with electrical parts cleaner, let dry, then reassemble.