Please help with understanding OBDII live scan results

https://www.toyotanation.com/thread...on-the-toyota-idle-air-control-valve.1676205/

 

@Timmah! Has a great video on the IAC for the 3.4
https://youtu.be/agIRNNA-6cs

You could check the IAC, @Dm93 posted it here
https://www.tacomaworld.com/threads/5vz-fe-idle-issues.760991/#post-27131162

This post says, it’s not uncommon to get carbon and deposit in the IAC if you have cleaned the TB.
It also explains some of the causes and fixes.
https://www.yotatech.com/forums/f4/5vzfe-how-diagnose-high-idle-tests-iac-etc-295444/

Hope some of this helps.

 

Thank you....
Funny though how the ahas are coming in. The once "mysterious" air assist hose from the IAC to the intake manifold. It then y's off, one side exhaust, other fuel side. Pinch off that hose & the idle drops as it should. But if it doesn't drop enough (which mine didn't), the (or a) problem lies beyond the hose, not before it.... Might be why the engine air intake passed a vacuum test yet I still hear hissing.

 

Make sure your IAC is working properly first but 1st gens also had a problem with the throttle body wearing and causing a high idle.
https://www.tacomaworld.com/threads/annoyingly-high-idle.688542/

 

When you went into the intake and eventually put it all back together did you use new gaskets everywhere? Torqued properly, etc? Those dual layer air surge gaskets for the upper and lower plenums pop into mind but there are others.

I was hoping your high idle was the ECU relearning air flow after your cleaning but not if it was many months ago.

 

oh yes. All new gaskets & seals everywhere & definitely by the book on the torque specs. I am not comfortable “eyeballing” torque specs for most things. I have wound up regretting that.

Case in point was recently I had the front driveshaft off to clean it & properly grease it. I also removed the rear part at the slip yoke to do the same.
54ft lb didn’t seem too high & given the PITB of fitting a socket on the bolts, I figured “I got this”. Now mind you, I don’t think much about my being a female wrench turner, I am simply an amateur wrench turner. However, I willingly acknowledge the difference when it comes to upper body strength. I often can make up for this by using pipes or longer torque wrenches. However, lying under the truck does not afford me much leverage. (side bar - The motor mounts were about as close to a nightmare regarding this as I have come. Had to use a lot of magyveretting & learned to take a lot of breathers/regrouping.)

So anyway, I started noticing some shimmying on take off. Kinda like my Toyota takeoff shudder had reappeared. & some vibing on the highway as well. Think I kinda gave it up in the beginning of my “kristi short story long” story, but I’ll finish anyway. Checked the driveshaft bolts & sure enough, whilst not super loose, once I tightened them to specs, all was good.
So I don’t care if it’s 53in lb or 54ft lb, for most things, out come the torque wrenches.

 

So here is a pic I took of the tb last year when I 1st started with the high idle.
I thought it was given a passing grade on here.

 

Ok. So as I look back. I actually had the idle down. I think finally it was decided to adjust the throttle screw. That would be after the above pic.

Then fast forward to the day I changed out the temp sender (the really PITB one near the firewall). I did it on a whim, just for fun. No. It had been an unheeded suggestion to do whilst I had everything apart. I felt the urge to later cross my t’s & dot my i’s. Don’t ask me why, but after swapping that out was when the idle went up. Checked to make sure I hadn’t dislodged any hoses, etc. Checked that the sender was threaded in good.

I later did the coolant sensor, the not as much of a PITB one up front, but that was after the idle had gone back up.

 

Disregard - I did not have it on the k setting - (wish you could delete posts)
I believe I found a culprit. I put it as “a” because I checked it & cleaned it not long ago, post high idle. Anyway, I’m now not getting any resistance reading off the MAFS.
Curious as to why the live scan shows it as operational.

 

You fixed it? What was solution?

 

I think I'm getting close. I decided to do a fuel pressure test. Very slow climb, but I reached the 44. When I shut off the engine, the pressure plummeted to 0. Restarted & pinched off the return line. The pressure spiked quickly. I have not looked a whole lot into it, however from what I've picked up so far, this points to the FPR.

 

Or maybe that's what's supposed to happen when the hose is pinched since the fuel pressure itself was ok. There is something up with either the FPR, injector(s) or pump since it wouldn't hold pressure. The injectors & pump were done last year. Hmmmm.... Right before the high idle issues started....

 

I’m not a mechanic, but I can’t see how fuel pressure would cause a high idle.
The ECM or something mechanical is my guess.
And by saying ECM., I’m not saying it’s bad. I’m say some data is being reported to the ECM and is telling it to bump up the idle.

 

Here was my thinking. I have no CEL's. I focused on air intake vacuum leaks because of the idle & I was/am hearing hissing. However I pass the vacuum test. So what else could be leaking? Maybe exhaust manifold or fuel/evap system.... I did the exhaust manifold crossover gaskets, which did bring down the idle some & now I pass the scanner smog test.

The hissing is coming from somewhere around the driver's firewall, which makes me think fuel/evap (It's not booster). I don't smell fuel, however it could be internal. I smelled the oil dipstick & it smells like fuel. Also I have a hum/whine on acceleration which I thought was the durned PS pump. Still may be, however I just read that a faulty FPR can make this noise on acceleration & can cause fuel to end up in the oil.

All my long term fuel trims are in the negative - too rich. & when I am idling, they hit the "might wanna be concerned" point. At least this is what I am getting from my research as I am now trying to teach myself what it all means. What's the point in owning one if it can't help with something like this?

I have also read that a FPR on the low pressure end can cause a high idle. Although this goes contrary to the fuel trim thing because low pressure would be lean. Hence, the big picture. The ECM trying to make sense of it all.... & I have not had a chance to research the A/F/O2 sensor data.

I have thought of this here there , then put it away in its box. It could be the ECM itself.

 

Oh, & I am definitely not dissin' what you are stating. I am sure you know better than I what would contribute to a high idle & I appreciate the input.
One thing that has been haunting me throughout this though, is that all that work I put into cleaning the engine is being reversed. So even if I am on the wrong path for the high idle itself, maybe it led me to one more thing that needed fixing that could help preserve what's left of my hard work.
I do think the throttle body warrants another looking at. On tap for tomorrow.... The MAFS checked out.
I'm tired. I hope that made sense.

 

So I pulled the vacuum hose from the fuel pressure regulator & I definitely smell gas. I think the mistake I made before was checking the end that comes out the front of the engine. I believe this is an indicator that the FPR is defective.

 

I went back to read this because, whilst it was exaggerated in tje video due to the angle, the shifting may have become not as smooth over time. I saw something in passing about adjusting the shifter or resetting it. Anyway, I couldn’t recall if you had mentioned this. Then read your post again & did want to acknowledge that I do agree with you. I have tried to remember to leave it in gear when shutting it off to at least help a little. Course someone is now going to tell me that’s bad to do for some reason, which would be good to know of course.

 

im guessing 2 or 3 things. fuel injector leak, bad upstream O2, bad temp sensor. All I have to work with are slightly negative fuel trims. im probably wrong about the temp sensor because I live in a hot ass desert where my temp spikes to 210 and stays there. yours never gets above 190 which I think would be fine in a colder climate area. the O2 sensor could be dialing too much fuel back if it's not working properly. you have an overall negative fuel trim meaning your computer is dialing the fuel delivery back for some reason. lean burns also tend to run engines faster/stronger.

FPR wouldn't be the problem. If it was, you'd see a dramatic positive or negative fuel trim. If it's stuck closed, your computer would dial the fuel trims down passed -25%. If stuck open or weak your trims would be +15% so I doubt it's the FPR.

 

It won’t hurt anything. But it won’t help anything either. If the idle is High, it will want shift into gear harder (from park) Mine does this, but only when COLD. Or if I let the engine warm up, the idle drops to about 550-600 rpm.

Your truck seems to idle high even when warmed up. I’d see if you can get that figured out first.

 

Ok. Wish I fully understood that, however it puts me a bit closer. Gives me info to work with. So I thank you for explaining.