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Greetings! I picked up my 2001 XLS, with a bad engine due to oil leak which starved its internals. It ran, barely, but enough to prove electrical, charging/starting, heat/AC and all options worked fine. When original 3.0 was taken apart, I noticed one cam gear had stripped its pin out, and rotated forward, which killed the engine. It ran though, and made metallic noises. The Avalon is in very nice shape, with under 195k on chassis and transmission. For $300, I couldn't resist. Having previous experience with the 1MZ, 2JZ, even 22REs, I enjoy working on Toyota products. I found an ES300, wrecked, and purchased a running 3.0, complete and with 130k on the clock. I noticed it was a drive-by-wire system, and minor differences in oil pan/timing cover/oil pump and accessories. All was swapped over, CPS and oil pressure sensors were left in the Lexus block. While the 1MZ was apart, new timing components, water pump, spark plugs, intake gaskets, valve cover gaskets/tube seals, cam seals, main seals, coolant hoses/thermostat, fuel and air filters, MAF cleaned, throttle body cleaned, and maybe i forgot a maintenance item, and oil control valves on both banks were newish from old 1MZ. There. That should do it, I thought! Fires right up, no leaks or odd noises. Idle is excellent. Took it for a spin, and noticed that obvious "catalytic" stench. Pulled codes for knock sensor, swapped both AND harness with denso goods. Great, no knock codes at all. Throttle input, ease into it, in park or in drive, car runs/shifts flawlessly. Quick blip on throttle, or in my case when passing a car, motor hesitates, sounds like it's fuel starved or misfiring, ease pedal back, again, runs fantastic. I was clueless. Hit the cruise control, and went home. Testes for fuel pressure, about 45 psi key on engine off. I did not have a proper banjo adapter to test while engine is running, which is what bugs me as I am eager to see PSIs while driving. Pulled exhaust manifolds and noticed catalytic media was very ashy and disintegrating. Perhaps a mistake, but i wondered how this car was maintained in the past, and gutted both converters. Throttle response improved, although now there's a noticeable rumble even without any leaks in the system. Got a code for convert threshold efficiency, no biggie, it'll receive new converters once this issue is resolved. Current codes are:
P0773 shift solenoid
P0420 catalyst system efficiency
That's all i have to work with. I'm really aiming at the TPS or weak fuel pump, just want to eliminate all problems. The shift solenoid code has me wondering, transmission received new filter and fluid, and it looked/smelled fantastic in there. Shifts flawlessly under part throttle, floor the pedal it will not downshift, just sounds like engine is misfiring or needs more fuel. All vacuum lines are connected properly. No leaks of any sort. I'm wondering if CPS sensors vary, or if any other electronics are different on the ES300 engine with DBW, compared to the original motor. This has me going nuts, but I'm eager to find the problem soon, this car has so much life left in it. Well, hope you enjoyed the story, please add any help to close the odd case!
Cheers
 

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Are these the injectors that were in it when you got it? Not sure about Avalon/Lexus, but the same engine will sometimes be fitted with different injectors across different makes/models. Also, the ECM may have different programming.

I would log injector pulse width, TPS, MAF and O2 sensors, then do a snap throttle on it first.
 

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Discussion Starter #3
Thanks for stopping by! They are original injectors/fuel rail. Only electrical items on Lexus 1MZ were CPS and oil pressure sensors. All other accessories and intakes/sensors were replaced with original Avalon items. NGK spark plugs were installed. I read somewhere about the throttle blades needing adjustment or so, but can't confirm. I'm at work now, and will probe into the parameters. Thanks again.
 

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Check fuel pressure at snap throttle. Sounds like the fuel pump is having a problem. Cheap thing to do, change the fuel filter. Sometimes it is the simple stuff.
 

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Discussion Starter #5
I have to invest in a better scanner. I have not had time to look at the Avalon. I'm currently looking into TPS failures, my old S10 blazer had no CEL for over 2 years, but showed identical issues to the Avalon under full throttle, no down shift, engine stumbling. Ease off the pedal, shifts continue smoothly, engine RPMs are steady. It finally flashed CEL, and a spare cured it. Anything specific regarding TPS issues or adjustments with the 1MZ? Fuel pressure drop is a maybe, but I still need a proper adapter to test system. No codes besides what's stated. Also, why would this shift solenoid code be related to the issues? Is this a 1-2 package deal indicating something else could be the culprit? I'm also going to compare part #s for sensors. Maybe i missed something.
 

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Discussion Starter #6
So, after scan i have these values:
Fuel sys 1 CL
Fuel sys 2 CL
Calc load 21.5 %
ECT 188.6 F
STFT B1 0.7%
LTFT B1 -28.1 %

STFT B2 0.7%
LTFT B2 -24.2 %

Engine RPM 645

Well, that's what i found. I'm taking it for a spin shortly.
 

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Does the engine react OK when the throttle is increased slowly? If yes, then it could be the TPS isn't giving a smooth change in resistance thru its stroke. When the throttle is snapped open, the ECU should respond to the sudden change in TPS resistance by commanding the fuel injectors to give a quick increase in fuel.
 

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Discussion Starter #8
I did probe, and had linear increase in resistance, about 65% near WOT, my DMM beeped continuity? Is that proper?
 

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I did probe, and had linear increase in resistance, about 65% near WOT
Your comment about it being 65% puzzles me a bit... Were you looking at the TPS via an OBD2 reader? Because if you weren't, you can. This will tell you if the ECU is "seeing" the TPS signal properly. It would be a good 2nd way to check what's going on.
my DMM beeped continuity? Is that proper?
Depends on which of the 4 terminals you had the probes connected to. See pic below. Which terminals did you probe? To check what I mentioned, should be across terminals E2 and VTA.


292609
 

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Long term fuel trim is super rich. Either a fuel delivery issue or O2 sensors would be my big fat guess.
 

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Discussion Starter #11
I need to do some further probing on TPS guys. Throttle response is delayed if pedal is snapped. At higher speeds, engine operates smoothly, but again quick throttle action and it runs poorly, like misfiring. Exhaust does smell rich. Converters were falling apart and gutted completely, which helped the motor run better and smoother. Even worse news, motor was running for at least one hour, in attempt to bleed cooling system. The entire time bubbles kept coming up thru cap housing. I'm starting to lose hope. I hope a head gasket did NOT fail.
 

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A car running that rich will stumble on a snap throttle. If you have enhanced Toyota PIDs on you scanner, log the misfire counter on each cylinder. See if it misses when you snap it. Lots of gas is getting in the cat. Not good!

I will snap throttle my Avalon and check TPS, MAF, and RPM. My Avalon has a bad bank 1, O2 sensor, and reads LTFT -7.9 on bank 1 at idle. Goes closer to 0 under load. I will post what I find out.
 

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Discussion Starter #15
A car running that rich will stumble on a snap throttle. If you have enhanced Toyota PIDs on you scanner, log the misfire counter on each cylinder. See if it misses when you snap it. Lots of gas is getting in the cat. Not good!

I will snap throttle my Avalon and check TPS, MAF, and RPM. My Avalon has a bad bank 1, O2 sensor, and reads LTFT -7.9 on bank 1 at idle. Goes closer to 0 under load. I will post what I find out.
Unfortunately, i do not have a capable scanner to show me any other information. I do have spare oxygen sensors, i will try both and see what happens. Also, the motor running rich is what im sure killed the converters, i can only imagine how this Avalon was maintained or how the repairs were done!!
 

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Discussion Starter #17
Here is my snap throttle.

RPM 5900+

MAF 103+ g/s

TPS% 61+ %

I assume these are normal, since the car runs fine.

Im suspecting an issue with too much fuel being dumped into motor. I read of a pressure valve or so near pump in the tank, I imagine it's a mechanical operation, no electric control of fuel pressure? The converters are completely hollow, will this affect the 1MZ so much? Ive ran motors without converters, and either they run great or i get a code of converter threshold, which means efficiency of catalyst action reduced or at its limits. Next to purchase are TPS and possible fuel pump/pressure valve. After this, im officially done if issues are not resolved. I also mentioned a possible head gasket failure, which i haven't had time to verify. Thanks for your time and wisdom, so far. Scanner is on hold, still shopping Amazon.
 

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There is a fuel pressure regulator, but it's not in the tank. It's mounted on the front bank's fuel rail, which is just downstream of the fuel filter.

Long term fuel trim is super rich.
I didn't notice that. My bad.

These fuel pressure regulators have a vacuum line going to them to adjust pressure accordingly. Sometimes they fail in a way that dumps fuel into that vacuum line. That might be why it's running so rich. Try disconnecting that line & plug it. Then start it up and watch for fuel spewing out of that spigot on the reg.
 

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Discussion Starter #19
Man, you're the Man! Priceless information. I'm going to invest in a better scanner, mine is just a basic reader. Head gasket issue is present, i believe guy who owned the Lexus ran the motor without coolant a bit too long, maybe in the time it was driven to have its motor extracted. I'm a bit let down, i must repair this leak before i continue diagnosing the hesitation problem. Until then, the Avalon awaits its new gasket set and good vibes in hope somehow the Avalon will run perfectly fine. Also, how are your MPGs with the bad O2 sensor? Here in WA state we do not have emissions testing, luckily! Thanks again for all your input. I want to document the head gasket repairs and post them here.
 

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There is a fuel pressure regulator, but it's not in the tank. It's mounted on the front bank's fuel rail, which is just downstream of the fuel filter.


I didn't notice that. My bad.

These fuel pressure regulators have a vacuum line going to them to adjust pressure accordingly. Sometimes they fail in a way that dumps fuel into that vacuum line. That might be why it's running so rich. Try disconnecting that line & plug it. Then start it up and watch for fuel spewing out of that spigot on the reg.
I did not see a vacuum line for the regulator. This is not a return- style system, as that action i believe happens in or near fuel tank. Out of curiosity, i swapped over the regulator on fuel rail from the ES300 motor, absolutely no change in performance. I have not found a banjo adapter to monitor fuel pressures while on a drive, which i feel is THE official way to really diagnose the problem here. Until then, I'm shopping for head gaskets. Take care
 
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