3rz-fe acting up (long post)

2000 4Runner with the 3rz acting up a bit. (270k miles)

Symptoms include intermittent idle drop/stalling, and hesitation when getting on the gas between 1500 - 2000 rpm.

No codes currently because the shop the owner took it to for a diagnosis cleared them for some reason. They said the codes stored in the truck were P0172, P0100, P0101, and P0420.

They believe the cat is plugged and wanted to replace it along with both o2 sensors for $1400.

I was asked to take a look and I'm a bit skeptical that the cat is the problem.

I did find the exhaust manifold had developed a small crack that I know will only get worse so I've got a Toyota mini-header on the way to resolve that.

While I was in there I decided to remove the cat to see if it looks plugged or if I could hear anything rattling around.

Problem is I can only look down the side that goes to the muffler and not the side that mates to the manifold without cutting the pipe. I figured you guys could tell me if it is necessary to cut it or not.

I don't hear any loose stuff or rattling and the muffler side looks pretty clear.

Downstream o2 was replaced several years ago and I just replaced the upstream because it looked original. (Both are Denso)

I got a quick vid of the truck running with a scan tool. If you look at the video the engine tries to quit and then picks back up. I've had it do this to me 4 times back to back in the driveway recently before it recovered and leveled off.

https://youtu.be/rx0v6BVaBgYhttps://youtu.be/t5ckZjywblY

 

Fuel injectors plugged and/or possible vacuum leak what comes to mind.

 

P0100/101 are Mass airflow sensor codes, p0172 is fuel system too rich, and p0420 is catalyst efficiency.
Looking at how the truck is acting it looks like the Mass airflow sensor is dropping out either due to a bad connection or bad sensor, I'd want to see the MAF reading when it acts up and while doing a wiggle and tap test on the sensor.
Diagnose that before you start chasing the rich and catalyst codes, it may fix all 4 codes.

 

I did find the main air intake tube was cracked right at the bend. It was replaced with no change even though it was most definitely a vacuum leak and a big one at that. Fuel injectors could be on the radar if no other issues are found.

 

I don't see fuel injectors being intermittent other than possibly a bad connection and a vacuum leak would cause a lean condition not a rich condition. Plugged exhaust would not likely be intermittent and would cause a lack of power under load not at idle.

 

You could be on to something. At idle the LTFT seems to hang around -9.4. If I increase revs to say 2500 or so the number actually goes positive around 6%.

 

Have you checked the condition of the MAF, it could just be dirty, that would cause it to be rich at idle and lean at higher RPM.

 

I drove the truck 60 miles from where it lives back to my place. It was 75mph highway the whole time. The only thing I noticed was a bit of hesitation when accelerating on the on-ramp. After that it seemed to drive well enough just cruising.

 

I pulled it. It doesn't look dirty but then again probably wouldn't be able to tell anyways those wires are so small. I did pick up a can of MAF cleaner and will be giving it a good spray before reinstalling when I get the new header on. Any specific tests I should do on the MAF besides watching it on the scanner or tapping it with the engine running?

 

Tap test should reveal any intermittent problems in the sensor itself, wiggle test should find any bad connections in the connector or wiring.
General rule of thumb is MAF G/s should be close to engine displacement with the engine idling unloaded at operating temperature.
You can also unplug it and see how it runs with the sensor unplugged, I can't remember how good Toyota's default strategy is for the MAF but most vehicles will run fine with it unplugged if everything else is good.

 

Excellent, I will perform those tests once I get it up and running again.

 

Also any chance the manifold leaking could have anything to do with this problem? I didn't think it would have a serious effect but I've seen some of the pics you guys post of these manifolds and talk of burnt valves and what not. I'll save myself that headache.

 

I can see it possibly causing a p0420 code but not an intermittent driveability issue.

 

Okay thanks.

 

your launch should be able to read the misfire count... see if it is an isolated cylinder or intermittantly different cylinders.

 

Not saying it definitely isn't misfiring but it doesn't appear to be. There are no codes for misfire and the scanner isn't detecting misfires when the truck is running either.

 

https://youtu.be/cMpxcCBx3Oc

Well the MAF failed the wiggle test horribly. Thing is, I'm not sure if the MAF is at fault or there is a short in the wires or a problem with one of the pins inside of the connector. I have inspected them on both the sensor and the connector and they look ok. I don't see any pierced or ripped wire sheathing.

The tab on the back of the connector that locks it in place is broken but doesn't appear to be a big deal as the sensor fits tightly inside of it once fully seated. There is no movement of the connector when I wiggle it.

Any thoughts?

Edit- Should of recorded in landscape doh.

 

ill bet one or more of the wires is broken internally where it is cripmed to the connector or the pin tesnions are shot.

You might find a shop that can repair this. When I had this issue with the connector on the auto trans for my 96 4X4 I had a hard time finding someone. I happened to be talking with my trans guy explaining the situation and he said, I know a guy... so, maybe talking to a trans shop in your area can put you in touch with a guy that can repair it. They would have experience in locating the correct pins and the correct crimping tool which is 99% of the battle. The Toyota dealer "might " be able to get the pins but you first have to deal with the kid at the parts counter.

 

I’ve been looking around on eBay trying to find a suitable connector for replacement, no luck so far. I already had to replace a coolant temp connector and an ignition connector. Everything is so brittle on this damn car.

 

Ok... I had some time to sit and think and do some research. Standard Ignition makes what I think you are looking for, S935 is the connector. The issue is they don't show me the end view. You might have to go to O'Reillys and see if they can locate one for you so that you can compare.