teaa

hey all, work I've done recently:
-Replaced both VVT solenoids.
-Replaced the wire harness on bank 2 (the connector piece was covered in oil, that's now on my to do list to find the issue)
-Replaced all 8 spark plugs
-Replaced ignition coil on spark plug 2

When I replaced the wire harness (for the passenger side VVT solenoid), it solved my P1354 code on bank 2. After that I was running with no codes at all. Engine running good. Now tonight I drive home, and as soon as I pull in the engine light comes back on. P0171. P0171 is bank 1, I have not touched bank 1 other than to replace the solenoid recently.

Why would P0171 (bank 1 issue) only start after I fixed the issue with bank 2? Never seen this code before

My next step is replacing the MAF sensor, just waiting for it to arrive. What else should I look out for?
Additional relevant info- car is in limp mode. Doesn't really rev above 3000 rpms. I will note though once I fixed P1354 my car has been running so much smoother, and the engine feels like it's getting more power to it when I accelerate. Just still not going past 3000 rpm

thanks for any advice

911LE

The new MAF may fix it. That code is for lean mixture on bank 1 and has nothing to do with the vvt solenoids. Could also be a vacuum leak or a dead fuel injector. That code won't put the engine in limp mode so you may have other issues as well.

Aus430

P0171 is too lean bank 1
The computer thinks it ir running too lean according to how much air it 'thinks' is getting into the engine.

Too lean can be cause by a few things...
- Maf (is the sensor reading correctly? I note you have a new one on the way... Is it from a good source like a legit toyota parts supplier or a denso from Rock Auto? Ie not ebay fakes)
- Air leaks from old hard brittle vacuum hoses (this is very likely - when was the last time these were refreshed, including pcv and grommet)
- O2 sensor 1 reading strangely lean (need to see the graph for behaviour)
- Air leak in the exhaust between engine and O2 sensor (unlikely but you may hear it)
- Blocked injectors on one side (unlikely)

Start with the first 2 on the list. Maf and vacuum hoses. It's remarkable how often it is one or both of those things. If it's not those two then lets get a data from the engine to see whats happening to the sensors

teaa

The new MAF is denso from Rockauto.

I have already had a few wires and hoses replaced in the engine bay. There were some cracked ones here and there. From what i can see all visible hoses now are fine. Im not sure about ones deeper in the engine.

I’m not sure when the pcv was replaced last. Will do that next as well.

thanks for this, its useful info. I’ll get back with more after the maf replacement

teaa

have been in limp mode for a while. Been trying to fix everything thru the engine to solve it but so far no dice hopefully I can catch a break with the MAF sensor

Aus430

How long is a while?
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teaa

couple months. The car drives fine, even into high speeds, it just doesnt rev above 3000. Most of the time I didn’t even have any engine lights at all. (Until recently)

I drive the car very light considering, I don’t push it hard. Really lost for the solution lol. Hoping one of these repairs eventually does it

Aus430

Only 3000 rpm when there was not light on?... let's see how the new MAF goes first. Let us know when you get it.

Do you have an obd scanner? Like an obdlink mx/lx or similar?

911LE

Does it rev over 3000 in neutral or does the exhaust sound different? Could be failed catalytic converters from running the incorrect fuel mixture for so long.

Aus430

Could well have fried or blocked cats from long term incorrect mixture running. Let's see the O2 sensor data plots from all 4 sensors before condemning them first. (Or take it to a local exhaust shop to do cat flow and backpressure tests)

I don't think we have found the root cause yet. Which means if the cats are fried and if replaced, any new cats will have similar early expensive demise from whatever is causing the main problem

Again all this is speculation on possibility without data to back it up. It could also just be the maf. Or a blocked fuel supply,.Or faulty O2 sensor. Or a faulty throttle body sensor or motor.or.or.or... Recording some obd sensor data would help narrow down what is actually occurring.

At least once the new MAF is in (which may very well fix it) we can then rule out the maf. And the vacuum hoses have been replaced so we can eliminate unmetered air.

Aus430

Has your Maf turned up? Did it make a difference?

teaa

MAF just arrived today. I installed it, the engine starts up fine, sounds better than the hesitated startup I was having before the new MAF. The engine codes (P0171 and P0174) have both been cleared and so far have not come back.
In terms of revving, in neutral it seems to rev the same as when driving. It still does not go above 3000. I did get it to pass 3000 slightly (maybe 3400) when I stepped on the pedal hard, but it's still not revving like it should.

Here's my data from my OBD2: Hopefully this suffices, this is just a cheap scanner from amazon
I apologize for the photos being out of order. Imgur did me dirty. There are currently no engine codes on.
https://imgur.com/a/En3wvLT


edit: both codes returned. P0171 and p0174

Aus430

What code reading set up are you using? I presume the moto 69033. Do you have any others? Are you able to data log with it? Or view the O2 sensor data as a graph?

teaa

Using the moto 69033. I don’t have any others. I have a cheap bluetooth one but that offers even less info than the moto one

if you mean log it to a memory card no this scanner doesnt offer that.

not able to view the o2 sensors as a graph, only the raw data itself

Can you recommend any budget scanners that allow me to do all that?

Aus430

What's the bluetooth one? Like an ELm327 style dongle? If so thats perfect

​​​​​​Install the ap 'car scanner' on your phone. It's free with ads or a couple of bucks for non ads version. It will allow you to configure 'dashboards' and will data log your trips if the app is running and connected.

The dash to configure is one that shows sensors:
Throttle position sensor
Maf
Engine temp
​​​​​Speed
​​​Rpm
All 4 O2 sensors
Ltft for both banks
Ignition timing

Record a 15-30 minute trip, one where the call for 3000rpm thing is happening so we can see what the computer is doing and how the sensors are responding


Disconnect for the car exit the app, go back into the app then you can see you data file recorded there.

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