If the it is going out of range when reving but is in range at idle I would get the fuel pressure tested and add a fuel cleaner. How is the top speed does it struggle. Fuel pressure could be blocked filter, kink in pipe, faulty pump or injectors could have poor spray pattern. Is the screw in the pulsation damper?
P0171 and P0174 Lean condition on my new LX470 ... (3 Viewers)
- Thread starter cwmoser
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Thread starter
- #22
I have a Fuel Pressure gauge. Does the LX470 have a port for measuring fuel pressure?
On my Isuzu Troopers there is a Shrader like valve I can screw the pressure gauge in.
The OBDII scanner does show that the MAF is putting out varying numbers depending on RPMs, etc.
What do you mean by "Is the screw in the pulsation damper" ?
On my Isuzu Troopers there is a Shrader like valve I can screw the pressure gauge in.
The OBDII scanner does show that the MAF is putting out varying numbers depending on RPMs, etc.
What do you mean by "Is the screw in the pulsation damper" ?
The pulsation damper is on the fuel Rail it has a screw in the centre that rises with fuel pressure, if it was missing I would expect you to get hesitation under load so it's probably there. Not sure if it has a schrader valve or you have to tee into the hose.
2001LC
SILVER Star
Pinch the green fitting and pull down, after cutting fuel pressure by pulling fuse.
You must discount battery when cleaning MAF.
I recommended getting on vehicle fuel injector cleaning at dealer, gets you free pressure test at some shops. They have the tool needed to connect to fuel rail for cleaning & pressure test. It is a specialized connection, cheaper to have them do.
In my first picture you see the pulsation damper (round thing). The fuel line (from filter) connects just under it on fuel rail. The return lines is just to the rear of it. The screw pops on when I cold starter my 01 (I've never looked if it stays up all the time).
Last edited:
You do need to start confirming test results. It could still be a MAF sensor as replacing not cleaning is required. But you need to use the test data to pin point or eliminate, fuel pressure test, injector spray pattern, vacuum gauge fitted to test air leaks and so on. Without these it's just guess work.
- Thread starter
- #26
I agree. I'm a newbie with this kind of stuff - but I do find it interesting.
It could be my code reader is not working properly.
I was able to get the TechStream software working this afternoon with my laptop.
Ran a series of diagnostic tests and they all passed.
I think its probably best to just take it to a Lexus service center and let them check it out.
2001LC
SILVER Star
I am very curious, what did you pay for an 02 with 25K miles on the clock? I assume it was show room fresh, no accident.
- Thread starter
- #28
I paid a premium - $23,500. She is like showroom new. Still smells new.
Came with a new set of Michelin tires, carcover, books, keys.
Previous owner was so particular that it came with hard plastic covers
for the floor mats - front, center and rear.
It really is a nice vehicle.
2001LC
SILVER Star
Wow.
I do like the pre 03's, my 01 LC has been solid as a rock and trouble free.
Did he give you some detail on driving habits and how often? How long it sat between drives. Did he keep fuel tank full while parked. Did he use a fuel stabilizer with gas tank protectant emitting gas. This info will really help you understand what's going on, and issues you may find.
Example; Fuel in gas tank creates moisture that eats (corrodes) lining of tank that is above fluid line. The sediment will then clog pick-up filter. Fuel sitting may also clog fuel injectors.
If PO didn't take proper precaution, you may want to look into gas tank. If you find corrosion, you'll need to take on repair, replacement & cleaning staring from rear moving through to Fuel injectors.
Ok Revivng this thread BC my Uncle is having P0171, P0174 and PO456
Is it ok for them to go on a 6 hr road trip to get the 100 home for further diagnostic?
2004 with 287k stock.
Is it ok for them to go on a 6 hr road trip to get the 100 home for further diagnostic?
2004 with 287k stock.
2001LC
SILVER Star
Difficult to say. Too lean and he may be running hot. If to hot, he could overheat and warp heads. Have him watch coolant temp closely if he must drive. Best is if he stops by a Toyota or Lexus shop.
Also ask if he's topping gas tank by filling past the first auto shut off at filling station. It may also help to add a fuel system cleaner like 44K, Chevron techron, etc.
Also ask if he's topping gas tank by filling past the first auto shut off at filling station. It may also help to add a fuel system cleaner like 44K, Chevron techron, etc.
Ok as some suggested in other Threads, Replacing the Gas Cap and resetting the battery got rid of all the lights.
A summer adventure is not an adventure without adversities. Bumping this thread up, I just got P071 (bank1 running lean) DTC here in Moab. All vacuum hoses are good, MAF is brand new, I even have a spare one that I tried. Symptoms:
• only happens when outside temp is hot (100°F range)
• only happens under load going uphill and in slow speed upto 45mph observed at 90°F outside temps (however if it’s mid 80°Fs it doesn’t happen), ECU threshold is able to process it.
• rough idling rpms @ low 700s with AC on (normal RPMs is in mid 800s with AC on).
• when dtc comes up I can easily smell the exhaust fumes smell different, smells like charcoal when you grill at home, definitely not the usual combustion exhaust smell.
• does not come up during 65mph and faster hi-way speeds.
• on the way to SLC from Moab as we speak, RPM is butter even at idle (outside temps here in Wellington UT is mid 70°F).
• no specific cylinder misfire, just a general bank 1 fuel system lean detected.
Actual diagnostic:
My short and long FTs on both banks going 70mph on 5th gear cruise control activated:
Next course of action is to get a temporary brand new aftermarket fuel pump in Lehi UT at Napa. I have ordered the Denso already and should be delivered back at my residence in LV NV in a few days in time when we get back from this trip. The FP is the most reasonable action component to address in respect with all the symptoms my 06LX currently have, I wish myself luck.
• only happens when outside temp is hot (100°F range)
• only happens under load going uphill and in slow speed upto 45mph observed at 90°F outside temps (however if it’s mid 80°Fs it doesn’t happen), ECU threshold is able to process it.
• rough idling rpms @ low 700s with AC on (normal RPMs is in mid 800s with AC on).
• when dtc comes up I can easily smell the exhaust fumes smell different, smells like charcoal when you grill at home, definitely not the usual combustion exhaust smell.
• does not come up during 65mph and faster hi-way speeds.
• on the way to SLC from Moab as we speak, RPM is butter even at idle (outside temps here in Wellington UT is mid 70°F).
• no specific cylinder misfire, just a general bank 1 fuel system lean detected.
Actual diagnostic:
My short and long FTs on both banks going 70mph on 5th gear cruise control activated:
Next course of action is to get a temporary brand new aftermarket fuel pump in Lehi UT at Napa. I have ordered the Denso already and should be delivered back at my residence in LV NV in a few days in time when we get back from this trip. The FP is the most reasonable action component to address in respect with all the symptoms my 06LX currently have, I wish myself luck.
