My '01 430 is currently getting about 12 MPG, does anyone know what could help? I recently put in some cheap grocery store fuel system cleaner into this current tank of gas I'm on if that's relevant.

 

any CELs? have you checked all of the usual stuff?

 

nope even ran an OBD scanner on it

 

Check for dragging emergency brakes on rear wheels, check all wheels for brake pistons that do not retract. If you have a temperature sensor or FLIR camera, go for a 1-hour highway drive, then check thermal readings of each wheel. The wheel that is much hotter than the others is the one with seized brake pistons.

Failing these obvious things, to fix poor MPG, acceleration hesitation (assuming no DTCs), and low idle with AC OFF, do my super-tune-up steps at every major service interval:

(1) Replace MAF with a new authentic MAF, the latest Lexus part number is 22204-22010 (supercedes 22204-0C020 and 22204-0D030), or Denso part 197-6030 from RockAuto (what I use). Don't bother with MAF cleaners, no cleaning agent will clean it as good as new, it's impossible to remove this burned on dirt without physical agitation, and physical agitation (e.g Q-Tip) will damage the MAF sensor wires.
(2) Replace engine air filter with a new 17801-50030 or Denso 143-2085 (I have both and verified they are identical) after 48,000kms of use (normal dust/dirt actually enhances efficiency of engine air filters up until they cannot supply enough air to the engine - see https://www.researchgate.net/publica...Diesel_Engines).
(3) Use the 3-step Toyota Induction Service kit - see - which is
(3a) Pour the Toyota EFI Pour-in-Tank Additive (00289-EFI00) into the fuel tank
(3b) Clean throttle plate and body with Toyota Throttle Plate Cleaner (00289-1TP00), and per official Toyota/Lexus service procedures, never move a drive-by-wire throttle plate by hand, instead turn key to ON position and use a heavy object on the accelerator pedal
(3c) Use an atomizer tool like Subaru SOA868V9430 / 10689 to spray a fine mist of the Toyota Top Engine Cleaner (00289-TECTL) or Penray 2312C into the upper engine intake. Make the connection between the atomizer tool and the vacuum port using a very short piece of fuel-resistant hose as a non-fuel safe hose will send dissolved hose internals into your intake manifold. Do 1/3 of the bottle in the PCV vacuum port, close the tool, raise engine to 2000-3000rpm for 10 seconds, then do another 1/3 of bottle in the EVAP vacuum port, rev to 2000-3000rpm for 10 seonds, then draw in the last third in the brake booster vacuum port, then rev burst to 4000-6000rpm 3-4 times to clear out the residue and to blow out the loose deposits.
(4) With the engine running, spray the throttle plate cleaner to clean the 8 small idle ports on the throttle body (you have to remove 2 Philips screws holding down the small cover plate) and into the 2 big ports on the vertical wall of that chamber (https://www.clublexus.com/forums/ls-...-cleaning.html).

(5) Run a bottle of Royal Purple Max-Clean just before every 2nd or 3rd oil change, at max treat rate (when low fuel light turns on, add one 6oz bottle and top with 30L of fuel). Drain all oil, replace with full synthetic 5W-30 (Pennzoil Ultra Platinum is very high quality), and replace filter with a Toyota 90915-20004 (very hard to find but super high quality), otherwise 90915-YZZD3 or 90915-YZZD4. D4 is for GCC/Middle East Toyota/Lexus UZ-series V8 engines, and is marginally higher capacity than the D3, which is for everywhere else.

You should already be replacing rear differential gear oil every 32,000km per original Lexus spec. If your diff has the #1 tag, use SAE 90 if you never experience colder than -18C, otherwise 80W or 80W-90. If your diff has the #2 tag or says it uses synthetic, then use synthetic 75W-90.

(6) Get a new battery, especially if you don't drive often. Use an onboard plug-in charger like the NOCO Genius GENPRO10X1 if you are going to be parked more than 3-4 days. A weak cell inside the battery reportedly causes strange electrical phenomena in the various ECUs. If you don't get a new battery, remove negative terminal for at least 5 minutes to reset engine and transmission learned values.

If the problem persists and you're ready to start refreshing parts, do some or all of these, listed very roughly from higher probability of solving the issues to lower:
* Replace fuel pulsation dampers (23270-50012, supercedes 23570-50011, 23570-50010, 23270-73010). Mandatory gaskets 23232-41081 and 90430-12026 on each damper. The factory-installed dampers seem to be defective hence the several superceded parts, and many people report intermittent gas smells traced back to this part leaking near invisible amounts of fuel.
* Use the large bottle of Toyota Pressurized EFI cleaner 00289-1PF14 (14 is for bigger engines, the 7 is for smaller engines) with EFI tool 00289-1PF00-01 to do a Pressurized Fuel Injector Cleaning - see * Replace engine coolant temperature sensor (89422-30030 and gasket 90430-12005)
* Replace the Evap VSV (25860-50100)
* Replace PCV valve
* Replace fuel tank overfill check valve (77390-50020) and corresponding gasket (77177-33010)
* Replace spark plugs with NGK Ruthenium HX (94279), ensure you use dielecric grease on the white ceramic part and on the inside of the boot that wraps around the spark plug head (but don't get any grease on the actual metal head, on the coil spring inside the ignitor, or on any parts intended to carry electricity such as the harness terminals)
* Replace fuel tank cap gasket (77316-16010)
* Replace the throttle body gasket (22271-50042) every time you remove that part of the throttle body - it is a non-reusable part
* If you have the 5-speed transmission (pre-2004), drain the T-IV and fill 1.6-2.0L through the dipstick port every 5000mi/8000km
* Clean the 2 transmission speed sensors (just one 10mm bolt to take them out - see https://www.clublexus.com/forums/ls-...s430-base.html)
* Clean the accelerator pedal position sensor (bang with end of screwdriver) or replace the entire mechanism, see pic at https://www.clublexus.com/forums/ls-...r-circuit.html, relevant part numbers 89452-30150, 89281-47010, 89452-22090, 78010-50010, 78010-50011, 78010-50020, Denso 198300-3010 and 198300-3011.
* Replace camshaft position sensors - see https://www.clublexus.com/forums/ls-...occasions.html
* Check the air intake muffler box (attached to the air intake connector pipe) for unmetered air being pulled into unsealed seams - see https://www.clublexus.com/forums/ls-...-05-ls430.html
* Replace fuel pump (23221-50090)
* Send ECU to Sia Electronics or Quantum Auto for "repair", likely replacing various resistors and capacitors and reflowing solder in defective/cracked solder joints
* Replace throttle position sensor (89452-30150)
* Replace at least the front 2 O2 sensors (234-4138, 234-4630), rears have minimal impact (234-4167). Use Techstream charts/graphs of your accelerator pedal sensor, throttle position sensor, O2 sensors, and injector pulse widths to see what exactly the car is doing when you go WOT. If there is no acceleration hesitation immediately after a cold start (before O2 sensors switch to closed-loop and before coolant gets to operating temp), this may indicate your O2 sensors are lagging. Also check STFT and LTFT for +/- >5% (I believe Lexus spec is under +/- 20%, but anything more than 5-10% each way indicates something isn't quite right).

 

It would be good to know exactly what kind of routes and driving style the OP has that yields 12 mpg. If it is all city, short trips with a heavy foot, lots of AC and idling, 12 mpg is normal. The route, length of trip, cold starts, city vs country, and driving style all have a HUGE impact on fuel economy with this car. The "right foot mod" will help a lot if the engine is otherwise healthy. What is the mpg on level ground at a steady 45-50 mph? do a test with the computer reading out instantaneous mpg; repeat; average results.

 

Thank you so much for this incredible list of fixes. I have fully cleaned my throttle body and removed it and that helped a little, when I drive on routes that are less stop and go I get the recommended 16-17mpg, but when driving my usual stop and go rout I only get about 13-14 now, a lot better so far, but I think it's just my route. I will try some of this stuff just for basic maintenance as I just bought the car with 200k miles, do you know any alternatives to the Toyota top cleaner and top cleaner kit? it was discontinued and is ludicrously expensive now.

 

I cleaned the throttle body and now I get 30-60mpg going perfectly flat at a higher speed, I think a lot of it did have to do with my route.

 

Sounds better. If you ever have the chance to take a road trip all highway at speeds below 70 you will get a lot better mileage - probably in the range of 25-30 if there are no other issues unresolved with the engine.
When I bought my car I went through replacement air and oil filters, oil change, drain and refill transmission and spark plugs. If you don't know the maintenance history of your car then maybe do that just to keep everything in tip top shape. Your plugs are due anyway at around 200K. A new MAF sensor is probably at good idea at your mileage. Keep an eye on your cooling system for any leaks and consider replacing the radiator cap with an OEM one - its a critical component to the cooling system.

 

Thank you! I am going to change the engine and trans oil this weekend along with the filters for both, I will save up for a new air filter, MAF, and spark plugs, all in all only like 300 so not complaining. My radiator cap is only very slightly leaking, every like once a week there's a tiny bit of dried coolant around it, nothing to worry about yet.