Got 'em all - P0300,301,302,303,304,305,306; P0172

[peirek]

Hi all,
OK first let me state this is about a Lexus. I know this is the Camry forum but there just are not that many DIYs on the Lexus forums. Same V6 as was in my 2006 Camry and 2007 Avalon.

I just recently purchased a 2001 ES300 (V6), knowing that it had some issues. 130K miles with original timing belt (more on this at the end). The owners were very old and were not sure when it started to run bad but think after the starter had been replaced. The receipt from the starter replacement showed no "diagnosis" or recommendation related to the poor running and/or CEL. The recent (Oct 2010) emissions testing was in the car and it passed. So this is a recent failure.

The gentleman has Parkinson and his wife just wanted the car gone because he wanted to drive..... So a great deal was struck.

Check engine light is on (along with the TCS light, which after reading, I find this is normal with a CEL) So, took it to Autozone to get the codes. Codes are as follows...

P0300-Random Misfire
P0301-Cylinder 1 misfire
P0302-Cylinder 2 misfire
P0303-Cylinder 3 misfire
P0304-Cylinder 4 misfire
P0305-Cylinder 5 misfire
P0306-Cylinder 6 misfire
P0172-System too rich bank 1

My search yielded many topics on single cylinder with P0300 and an entire bank (even or odd) but none with ALL 6 cylinders showing a mis-fire condition. I suspect P0172 is a net effect of the mis-fire events and am ignoring for now.

Seeing this likely occurred after the starter replacement I started investigating anything and everything that might get touched during this effort.

Visually checked all hoses for vacuum leaks, and nothing found. Tested the resistance on the MAF sensor at pins E2 and THA, and they were reading 1.98 Kohm at 75 degrees air temperature, which seems to be close to what the specs are. Took out the MAF, and it looks very clean, almost new. I inspected the 3 front coil packs which are easily accessible, and they are clean, with no signs of arcing. Checked all the fuses under the hood. Checked all grounds under the hood. It appears that one of the O2 sensors has been replaced, as it looks new and clean. It's the one that you can easily see next to the starter, not quite sure yet what bank this one is.


I am leaning towards timing belt slipped a tooth.

Other thoughts are encouraged and welcomed.


Thanks in advance,
Paul

[pmesfun]

Originally Posted by peirek

Hi all,
OK first let me state this is about a Lexus. I know this is the Camry forum but there just are not that many DIYs on the Lexus forums. Same V6 as was in my 2006 Camry and 2007 Avalon.

If I understood what you said the Camry have the same V6 both 1mz-fe, but the Avalon has the 2gr-fe.


Anyways, check the crank sensor, cam sensor.

Replace the spark plugs since they are already due.

From Factory Service Manual:
P0172 :
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)

Trouble Area:

• Fuel line pressure
• Injector leak, blockage
• Heated oxygen sensors (bank 1, 2 sensor 1) malfunction
• Mass air flow meter
• Engine coolant temp. sensor
• Gas leakage on exhaust system

[fenixus]

. nvm, just realized it's about '01 lexus

[71Corolla]

Originally Posted by peirek

I am leaning towards timing belt slipped a tooth.

I would check that first, it won't take long. I remember reading about a guy that a similar problem on an ES300, but it turned out to be the ECU itself, but he had even more codes than you.

[fenixus]

^
timing first. too many codes at once, besides System too rich code really doesn't happen too often.

If MAF tested good, then it's time to take a closer look at Engine Coolant Temp sensor and both o2 or AFR upstream sensors, they all may call for replacement.

AFR sensors do not last (while still giving functional results) usually more than 150k miles.
o2 sensors last even shorter, maybe 100k miles on avg.

ECT for EFI sensor can generally screw up everything in engine because it's a primary unmonitored feed to ECU, it's only $45 new OEM from Toyota dealer online, I replace hem at same time when doing major tune up and replacing all o2/AFR sensors.
test the current one for resistance on cold (high up to 20k ohm range) car and warmed up (shut down engine, resistance in 200-300ohm range) car and compare to this diagram:

[JohnGD]

System too rich is rare. It's like the oxygen sensor couldn't see any oxygen. If the ECU tries to lean out the mixture incorrectly then misfires will happen.

I'd try swapping the two (identical) upstream oxygen sensors and see if the Bank 1 (firewall side) sensor code (P0172) moves to Bank 2.

Originally Posted by peirek

took it to Autozone to get the codes. Codes are as follows...

P0300-Random Misfire
P0301-Cylinder 1 misfire
P0302-Cylinder 2 misfire
P0303-Cylinder 3 misfire
P0304-Cylinder 4 misfire
P0305-Cylinder 5 misfire
P0306-Cylinder 6 misfire
P0172-System too rich bank 1

My search yielded many topics on single cylinder with P0300 and an entire bank (even or odd) but none with ALL 6 cylinders showing a mis-fire condition. I suspect P0172 is a net effect of the mis-fire events and am ignoring for now.

Seeing this likely occurred after the starter replacement I started investigating anything and everything that might get touched during this effort.

It appears that one of the O2 sensors has been replaced, as it looks new and clean. It's the one that you can easily see next to the starter, not quite sure yet what bank this one is.

I am leaning towards timing belt slipped a tooth.

Other thoughts are encouraged and welcomed.


Thanks in advance,
Paul

[peirek]

Thanks for all of the responses. As is normal, some very valid points and great ideas to pursue. Appreciate the ability to bounce ideas off of everyone here.

I am really focused (right or wrong) on a single point failure. As I had described the car was in for a starter replacement and the receipt listed a couple of other items (struts and brakes) that may need replacing but nothing on the CEL. So I am assuming the failures happened at one time after the starter replacement. I also did not mention the car runs like it is truly misfiring on all cylinders. No power and stumbling like mad. So I am going to focus on sensors that can have an affect like this. For instance I would expect the ECU to go into an open loop default settings if an O2 or temp sensor was giving out of bounds readings. Is this not true?

From JohnGD: "System too rich is rare. It's like the oxygen sensor couldn't see any oxygen. If the ECU tries to lean out the mixture incorrectly then misfires will happen. I'd try swapping the two (identical) upstream oxygen sensors and see if the Bank 1 (firewall side) sensor code (P0172) moves to Bank 2."

This sounds logical but do you really believe the ECU will react to a no-oxygen sense and lean out the mixture enough to cause misfires? I would expect the ECU to fault the O2 sensor and resort to default open loop settings.

From fenixus: "timing first". I assume you mean crank/cam timing. Or should I check ignition timing? How does one do this on a COP setup?

From fenixus: "ECT for EFI sensor can generally screw up everything in engine because it's a primary unmonitored feed to ECU".
I need to do some further investigation as to where I can find the ECT for EFI sensor. This sounds like a logical single point failure.

From pmesfun: "Check the crank sensor, cam sensor". Are there 2 (or 3) sensors or just a crank sensor? I will need to research their location. Again a logical single point failure for sure. Originally I was of the opinion P0172 is a net effect of P0300 and it's accompanying codes. But reading the diagnostics from this code, it could be causing the P030x codes.... [IMG]file:///C:/Users/Dad/AppData/Local/Temp/msohtml1/03/clip_image001.gif[/IMG]

I think this should be my plan of attack in priority order:

1) Check crank/cam timing via timing belt alignment checks.
2) Check ignition timing.
3) Check crank and cam timing sensors
4) Check ECT for EFI sensor.
5) Start running down the list of failures for code P0702:
- fuel pressure (this could certainly cause mis-fires)
- injector leak/blockage - on all cylinders?
- heated oxygen sensor(s) - again would not expect this to cause P030x
- MAF - need to test that it senses airflow and reacts correctly
- Engine coolant sensor - could this cause P030x and poor running?


It may not be until next weekend when I get time to attack this again. Stay tuned.

[fenixus]

after second thought, I would check the ECT for EFI sensor first. it's easiest, right below the rad cap on engine. there is 2 sensors right below the water outlet pipe (on passenger side).
the one closer to windshield is the ECT for EFI (on 1mz-fe engine), unplug it (2-wire connector) on warmed up car (shut it off first) and measure resistance between its terminals.

ideally it should be like ~250ohm at fully warmed up car (around 90C). if you can see anything above 1K ohm, then you have the answer to why ECU makes the mixture so rich, it would be thinking the engine is cold.

[peirek]

Originally Posted by fenixus

after second thought, I would check the ECT for EFI sensor first. it's easiest, right below the rad cap on engine. there is 2 sensors right below the water outlet pipe (on passenger side).
the one closer to windshield is the ECT for EFI (on 1mz-fe engine), unplug it (2-wire connector) on warmed up car (shut it off first) and measure resistance between its terminals.

ideally it should be like ~250ohm at fully warmed up car (around 90C). if you can see anything above 1K ohm, then you have the answer to why ECU makes the mixture so rich, it would be thinking the engine is cold.

OK. Sounds easy enough.

[peirek]

OK a couple of lessons were learned on this one. The first and most important is read your own codes..........

Autozone said the car had all of the codes....... well that was not true and was very misguiding to say the least.

So going with the codes as mentioned we did the following:
1) Checked the ECt for EFI sensor. It checked out OK
2) Checked crank and cam timing via timing belt - OK
3) Pulled plugs - Oh my #6 was really bad. Full of gunk. Not firing for sure.
4) Replaced plugs (all 6) - still running bad.
5) Got my code reader working on my laptop and read the codes. P0306 was set.
6) Swapped coil #4 & #6 and code came up P0304.
7) Replaced coil and all OK

Second lesson - Suspect the obvious first.... Should have listened to pmesfun and changed the plugs first. Would have saw #6 and how bad it was.........

Oh well, thanks for all the help and the sounding board.

Paul

[pmesfun]

You should expect way better mpg now.

[fenixus]

huh, grats on solving this one!

it helps to have own scanner and double check the codes after some repairs, helps a lot to have it handy

so you never had all 6 cylinders misfiring codes at same time?

[peirek]

not when I read it.