2, 4, 6, All lean, Why? Need Help!

[73sport]

All,
I've got 95 1MZ with fuel issues. Its my only ride and can't be down for long. Its sittin at 220,000 miles and shot out a P0302 (misfire #2) when pulling a long grade at running temp. Its never lit the CEL until now and you could tell somethin was up with hesitation, stumbling, a kinda bucking feeling which could happen at almost any throttle position, but almost always under load. Other than a little hesitation over the past 3 days, this came without warning.

So I pull the three plugs (near the grill) bank2, they look well used for 60,000, not black, just worn and with deposits around the end. Now the bank 1; 1, 3, and 5, they look like new until you look real close and see metal balls on ground and electrode. They look electrically worn but otherwise brand new and have zero deposits. They don't look overheated or burned, just glossy right where the spark jumps. Cyl #1 was partially full of oil so this may account for a mis, but I think the mis was brought on by the lean condition AND the oil in #1 well.

I dump the fuel filter, replace it, replace the aged plugs, and remove the oil in the well (I'll deal with that later). Some grit came out of the fuel filter but no water. Afterwards it starts, runs, idles, and genuinely behaves as it did before a few days ago but it pings under load in the upper RPM's (1/2 throttle on up) until I back out of the throttle OR the knock sensor kicks in and you hear it make a series of "tink, tink, tink" sounds.

So my question is this: What is the most likely place to plug or restrict the fuel flow? Should I go for pump tests, or fuel rail inspection of some kind? Suspect bank1!

Key faults, stumble at upper RPM, pinging, detonation, under load. I added some Techron and topped the tank off. I'm welcome to ideas so any hints on trouble spots would be much appreciated.

Thanks in advance!
73

EDIT: cleared up text for more precise read

[tomtom25]

I just had to rebuild a 1mz motor out of a highlander due to excessive sludge like the guy never changed his oil or something but after i got it all done I had a misfire code for cylinder 4, ran a pressure test and found that he had bent 2 of his intake valves. I removed the head and replaced the 2 valves and still had a random misfire code for #'s 2, 4, and 6, it ended up being the vvt-i valve was stuck from the sludge getin into it and freezing it up. Not sayin that you have sludge or nothing like that but I would check the vvt-i valve it woud give you a random misfire code for 2, 4, and 6 or vise versa for 1,3,and 5 but if it's 2,4,and 6 then that's your bank 2 which is the head closer to you when lookin at the motor and the valve is towards the right just below the valve cover. That would give ya a tick and and misfire but the only way to accuate it to make shore it's working properly is by hookin the computer up to the vehicle and doing a active test. Might not be your problem but just know I had a similar problem and that's what it ended up being.

[jetwhine]

73sport.

Before you do anything else, I would try some injector cleaner. "BG products makes one of the best injector cleaners on the market. Its called 44K and is not cheap. Its about $35 dollars per container. It sounds too me like you have dirty injectors. You might give this a try first.

[EEngineer]

Originally Posted by tomtom25

I just had to rebuild a 1mz motor out of a highlander due to excessive sludge like the guy never changed his oil or something but after i got it all done I had a misfire code for cylinder 4, ran a pressure test and found that he had bent 2 of his intake valves. I removed the head and replaced the 2 valves and still had a random misfire code for #'s 2, 4, and 6, it ended up being the vvt-i valve was stuck from the sludge getin into it and freezing it up. Not sayin that you have sludge or nothing like that but I would check the vvt-i valve it woud give you a random misfire code for 2, 4, and 6 or vise versa for 1,3,and 5 but if it's 2,4,and 6 then that's your bank 2 which is the head closer to you when lookin at the motor and the valve is towards the right just below the valve cover. That would give ya a tick and and misfire but the only way to accuate it to make shore it's working properly is by hookin the computer up to the vehicle and doing a active test. Might not be your problem but just know I had a similar problem and that's what it ended up being.

95 1MZ has no VVT-i

i say it could be the injectors, try do a injector flush, but then this is really a hard problem to guess.

[tomtom25]

the 1mz motor i did was in a 03 highlander but toyota also has a injector cleaner that you can try that hooks right to your fuel rail an just gota run the car off that can till it cuts off then hook the fuel rail back up. It aint cheap either but works great too but that 44k he was talkin about is good sh*t too I got a couple cans here that I use in my cars and sometimes even on my bike.

[73sport]

OK - I hear that and don't doubt that ride having this many miles would need some cleaning, but the odds of an entire bank being deprived point towards something else cuz it basically happened over night. Then again I'm assuming and likely will not be yanking the back plug for a spot check. PITA! No PC/OBDII on board either for live data. << I know the CAR has it, I don't at the moment!

Are there any known issues with plumbing, fittings, pressure regulators, cross over pipe, ect. . . areas that could plug IF debris got past the fuel filter?

Something happened quickly and I don't expect anything I poor in the tank to undo what's been done by driving it. Its got 50 mile round trip starting in T - 30 minutes so I'll learn something pretty damn soon.

Thanks, 73

Edit: as expected, no change, lean above 5/8 throttle on first 25miles of 50.

[hill8570]

Rear bank tends to run a bit lean, anyhow, since the fuel rails are daisy-chained instead of run in parallel, so a pressure problem is going to I don't think the crossover from the front to rear bank (on passenger side) is small enough to get clogged easily, but you might want to check it for mechanical damage.

Do you have a reader that can pull the monitor for the rear bank O2 sensor? It'd be interesting to know if the lean is being commanded or if the O2 sensor is reading lean and doing it's best to compensate.

I'd probably start troubleshooting at the fuel pressure regulator (driver's side end of front fuel rail). Pop off the vacuum hose, sniff test to see if smells like gas (indicating leaking diaphragm). Hook Mityvac up to vacuum line and make sure regulator responds to vacuum. If possible, actually hook up a pressure gauge and check pressure.

I don't think there is any sort of failure of the pulsation damper (driver's side end of rear fuel rail) that could cause low pressure, so probably no point checking there.

[AlmightyCamry777]

Weak fuel pump? Every fuel pump that went bad, that i ever saw simply quit, they have all been like light switches either on or off - but a weak fuel pump is possible maybe?
also some of the toyota fuel pumps have a strainer built in to them. On my 2002 V6 there IS no fuel filter, only the strainer in the fuel pump.

[chronoti]

all the mz are obdII and the 95 is the 1st year of the correct connector behind the coin box.

check your o2 sensor if it only the rear bank then it the rear sensor is reading rich and leaning out

free loaner tool up a pressure test kit from your local part mart, they should have one that hooks in through a banjo nut and have in the kit a longer nut so you can mount it on top your filter and still leave the lines hooked up,

low pressure clamp the return line and see if there is a raise (should be too high when clamped), if not then the pump, or if all good time to look somewhere else

[73sport]

Thanks for the details everyone!

Ran the first 25 mile leg to work. As expected its all good until 5/8 to full throttle under load. It hesitates and stumbles as if lean.

Because it came on all at once, I suspect the last load of fuel dumped a load of crap in the tank and either the strainer, pump, or something in the metering after the filter is 1/2 plugged or damaged as this was a strong V6 that would easily pull 7000.

Looks like the spec is 38 to 44 psi for the pump after the filter but I don't see a volume test except the injector itself. Anyone have a number for this?
I have vacuum pump and can pull a vac on that diaphram, no knwon options for the banjo fitting but I do have a pressure gauge. I'll look for an extenda banjo bolt - kit, if not one of the return lines looks to be sorta hose clamp friendly. I'll try to avoid the whole "bursting into flames option". :/

Bingo got an OBDII reader for the weekend. . . he says its a autotap http://www.autotap.com/
Please keep the details and ideas comming! The more ideas I have now, the better!

Anyone replace a pump due to volume issues (natural asp only)?

[EEngineer]

ahh it also could be that your timing belt slipped and you are getting incorrect timing for your rear bank....makes more sense

[73sport]

Found this while doing a search. Some good information in here but it doesn't help my cause at this point. Looks like page 36 - 46 of a 98 1mz from the Toyo manual. Has A/f curves, sensor data, SFI, ESA, IAC, vvti, accoustic stuff. Worthy of a glance i'd say.

http://alflash.com.ua/RX/1MZ-FE_Engi...emRX300_99.pdf

[scotto-]

A couple of small possibilities; cracked grommets on fuel injectors from heat and age which usually causes a fuel leak, rather than a vacuum leak, or the o-rings on the injectors breaks down and disintegrate, causing fuel delivery problems. I've had this happen on my 3vz-fe and it's an easy and cheap fix. Hope you get it straitened out soon.

[73sport]

Have some new info which makes it more confusing.

I've driven it about 75 miles since plugs and fuel filter. It starts and idles fine but doesn't like to pull the hills when cold. Overall it runs very smooth at lower rpms and works fine for light acceralation onto freeway but may hesitate.

What seems strange is that it will pull to 4500 if done gently and sustain a strong pull to 6000, but pings if you romp on it in low gear.

So what is wrong with it that allows maximum fuel flow at for sustained upper RPM but doesn't allow quick accelleration? This makes me think it is NOT the fuel pump or strainer but I could be wrong.

I'm picking up OBDII laptop and software to get live data tonight so by Saturday I may have some readouts from the sensors.

Edit - I'm still looking for a value on pump volume. How is this tested as it must require backpressure to be of any value. Hence filling a volume through a metered orfice to create back pressure and have some head pressure. Ideas please. . .

[hill8570]

Originally Posted by 73sport

Have some new info which makes it more confusing.

I've driven it about 75 miles since plugs and fuel filter. It starts and idles fine but doesn't like to pull the hills when cold. Overall it runs very smooth at lower rpms and works fine for light acceralation onto freeway but may hesitate.

What seems strange is that it will pull to 4500 if done gently and sustain a strong pull to 6000, but pings if you romp on it in low gear.

So what is wrong with it that allows maximum fuel flow at for sustained upper RPM but doesn't allow quick accelleration? This makes me think it is NOT the fuel pump or strainer but I could be wrong.

Well, when you romp on it the vacuum drops a bunch for a bit, which should trigger a bump in fuel pressure from the regulator...if the regulator is not responding to the vacuum spike (or responding slowly), you're going to starve the engine. Doesn't really explain being able to pull at 6000, unless it's still running lean there but the knock sensor is backing off timing...just doesn't seem likely, 'tho. Gah...I'm still thinking the regulator, with the O2 sensor being the secondary suspect. I take it you haven't been able to track down an extended banjo bolt or a banjo fitting for your fuel pressure tester? You could sort-a kind-a do a test where you apply full vacuum (~20 inches) to the regulator, then pop loose the vacuum and see how quickly the engine changes it's song. Not super useful when you're not under load, but better than zero...