Lx470 VVTi misfires on startup, random stalling during low throttle

[scanderson76]

Hello all, I have been narrowing down an intermittent fault I keep having. Deduced the
spark plugs, coil packs are not the issue along with the battery and alternator as potential problems. It started a couple weeks ago, when we were coming back from a beach trip and the LX just died when coming down over a pass ( low elevation). Went through the troubleshooting process and after running fuel trims (see below) looking for more help from the collective group. I just cleaned the MAF, but I'm thinking after 260K miles the fuel pump might be giving up the ghost. The Torque screen shot is during minimal throttle and the attached fuel trim csv is covering bank 1&2 short term and long term fuel trims. Looking for any insight or further tshooting before I bite the bullet on a new fuel pump. Of note, my first thought is the long term looks a little off. Thanks.

 

[scanderson76]

Here is the csv

 

[scanderson76]

Anybody have any ideas on this issue? Do you need more context? Is there another method to testing the fuel pump?

Thanks all for any support.

 

[GTV]

How did you rule out the coils?

 

[OEMGUY0720]

It appears your Long Term fuel trims on Bank 2 is compensating, it should be lower (in the 0s and1s range on low rpms) and near identical to your bank 1.
Check vacuum hoses, they're on the passenger side/intake side of the engine and just make sure none is loose and/or cracked.
If those hoses are good, it can be your fuel pump. I just went through this last week,, I can relate. See this post.

 

[scanderson76]

How did you rule out the coils?

I still have my old ones as spares. The misfire codes have been all random, but I did swap back and forth to see if I could get it to follow with no luck.

 

[scanderson76]

It appears your Long Term fuel trims on Bank 2 is compensating, it should be lower (in the 0s and1s range on low rpms) and near identical to your bank 1.
Check vacuum hoses, they're on the passenger side/intake side of the engine and just make sure none is loose and/or cracked.
If those hoses are good, it can be your fuel pump. I just went through this last week,, I can relate. See this post.

Thanks OEMGUY for the response, I also noticed that as well and did check the hoses and all was good, tight and nothing was cracked. Yeah, kind of frustrating, but the fuel trims have been pretty telling as I have been driving a little and noticing some more oddities.

 

[Manhattan]

A few years ago, I had a somewhat similar issue. The 100 ran normally. I parked it. An hour later, I went to start it and it sputtered, coughed, started - ran rough - rougher at low RPM, stalled... kept doing this. I called my buddy Dugan who happens to own ACC Garage - a Land Cruiser shop. He suggested cleaning where the actuator plate seats in the throttle body. (wiping with a very clean microfiber)

I had a crappy set of tools - one of those dumb screwdriver things with socket attachments - and spent 20 minutes getting to the TB and 5 minutes cleaning it. But it worked.

Full disclosure: I called Dugan back and told him it worked. He responded, "Holy *&#%. I gave that a 5% chance of solving it. But, with your tools and knowledge (yeah), that was about all I could think of that you could do there." I now carry a much better collection of real tools... but same knowledge.

 

[scanderson76]

I replaced the fuel pump and the tensioner pulley assembly over the weekend, and that seems to have solved the problem. The fuel trims look much better now. I think the tensioner was a contributor, but I don't want to speculate until I have the time to pull it apart and inspect it further. The bearing on the pulley was replaced, but it was still squealing something fierce on the inside of the assembly itself.