Any toyota guys here??

[JustJason]

Trying to help out the folks here.....
Got a 00 Avalon. 3.0L 1MZ-FE engine. 112K on the clock. Heavily neglected.
Runs like a dog. Had a MIL on. Borrowed a buddys lower end scan tool. Got a P0179 code. "bank 1 lean".
Thing is never maintained. (not my car). Figure I'd start off with plugs (believe they were the originals... they came out pretty rough) Fuel filter, air filter, PCV, oil change. Flipping back the throttle plates revealed about 10 pounds of sludge in the intake manifold. So I seafoamed it as well.
It helped a bit, but not enough.
Same code. I don't have a waveform analyzer but I tested the rear (bank 1 O2 sensor *which is really a wideband O2, more of an air/fuel compensation sensor than it is just an O2*)
I have a manual for an 02 camry with a 1MZ-FE engine so i'm hoping the engines are the same. Anyways, That manual has static resitance checks for the O2. Bank 1 O2 fails resistance check and bank 2 passes. I go ahead and replace bank 1 front O2. I clear code, run for 10 to 15 miles. Hard runs, from 0 to 70 at WOT. Its got a little stumble between 2-3K then picks up and takes off. Not to bad of a stumble, but it still should not be there.
So I give the car to the folks and explain to them what I found. They take it for the weekend and right around 150 miles after I give it to them It has another MIL and has a worse stumble.
Scan it again, this time I'm getting a P0171, "system to lean"
From a dead stop. Pressing the accelerator to WOT causes a few backfires that are contained in the exhaust pipe. It stumbles, then takes off. Mid range acceleration is excellent. (probably from the lean condition).
I'd love to fix it for them But i'm a boat guy and not a car guy.
Went to school (and yes finished) for boat engines. But I don't have any training on emission controls and do not fully understand them.
I did find 1 vacuum hose with a small tear at the end. I believe it was attacted to a VSV. (vacuum switching valve). I snipped the end of the hose to remove the split and reinstalled it. And again it's better, but still pops. I spent 2 hours today looking at every intake joint I could for a leak, but I couldn't find one (that doesn't mean that ones not there either) After clearing the P0171 and a couple of hard runs, the code hasn't come back yet but I'm sure it will as it's still not right.
Anyone have any experience or advice on these 6 cyl's they can share with me... I'd Appreciate it.
Cheers!
Jason
Anyb

 

[JCF350]

Re: Any toyota guys here??

Since you don't have a scan tool with data stream access it ain't easy.

But I would check for a dirty Mass Air Flow sensor. Can be cleaned with q-tip and alcohol using extreme care. The dirt throws the reading off a bit while still staying within operating parameters.

Lexus, Avalon and Camry share a lot of parts by the way.

 

[JustJason]

Re: Any toyota guys here??

Thanks JCF,
I have access to a scan tool with data stream and freeze frame... its just a 300$$ one and not a snappy or genesis or oem.
As far as the MAF. It seemed to be in order. I got good reading compared to the charts. I also performed all the static checks I could on the likely culprits.... The Maf, the A/F sensor (wideband o2's), the tps. All check out so far. The only thing that stands out is the long term fuel trim in in the negatives quite a bit.... and i don't know why yet. It's almost like i'm chasing a pinhole air leak but haven't found it. I was hoping there would be a toyo guru on here somewhere. being neglected... i'm totally open to there being more than 1 problem to.... we'll see how it goes.

 

[WizeOne]

Re: Any toyota guys here??

Check for any possible vacumm leaks. On another vehicle I changed out the plug wires and inadvertantly knocked a PCV line out of the fitting on the valve cover. Shortly after, I got a check engine light with a lean code.

112k miles on an '00 Toyota is nothing. I have a 1991 4 cyl Toyota with 124k on it and it has NEVER been to the shop. I have changed the oil, put in one set of plugs and wires, blew out the air cleaner, put on two sets of front brake pads and one set of rears and now into the third set of tires. That's the extent of the maintanance.

As stated, I'm sure your lean code is something simple.

 

[JustJason]

Re: Any toyota guys here??

Thanks Wizeone....
I'm not thinkin this one is simple.... I was hopin a toyo guy may have more insight on a P0171 code...... That used to be a P0179 before a new bank 1 o2, plugs etc....

 

[JCF350]

Re: Any toyota guys here??

Thanks JCF,
I have access to a scan tool with data stream and freeze frame... its just a 300$$ one and not a snappy or genesis or oem.

Your reading OBDII Generic data stream it is very very slow and nigh useless (updates something like 4 times per second).

As far as the MAF. It seemed to be in order. I got good reading compared to the charts. I also performed all the static checks I could on the likely culprits.... The Maf, the A/F sensor (wideband o2's), the tps. All check out so far. The only thing that stands out is the long term fuel trim in in the negatives quite a bit.... and i don't know why yet.

Static ain't gonna help on the MAF reading that is a "hot wire" sensor and needs air flowing over it, if there is anything on it it will it will change the "temperature reading" across it and give an incorrect air flow reading. Ergo the system lean code and long term fuel trims.

Your not following the the chain of events
1 the O2 since repaired
2 changed plugs and filters (more than likely dislodging some dirt in the
air filter case). "Neglected car"
3 the system appears to be improving with high rpm runs (possible
indication that the increased air flow is pulling dirt/dust off of the MAF).

I suggested a visual inspection of the MAF because it is simple to do and is common problem on all makes, especially neglected ones. The most likely connection between the the 2 codes was what you did to the vehicle (it wasn't wrong it's just happens a lot).

 

[dolluper]

Re: Any toyota guys here??

A leak down tester may be what you need......things to check ...the Plenum gasket......O-ring gaskets on fuel injectors......Idle air control ''''plus more cleaning as you were talking out how dirty the throttle plates were