Fuel trims and VERY low MPG

[hikerfisher]

Hey hundy folks. I’ve got lousy mileage suddenly on my 06 LX. Got the common 420 430 DTCs, new aftermarket cats, all 4 O2 “sensors” from Denso. Smooth start up, no misfires, no acceleration issues, engine SOUNDS great. But, cruising on the flat at 65mph getting 10 mpg, where I used to get 17 or even 18 (about 2150 rpm). Stock tires no lift, AHC out, replaced with LC suspension.
At 65 mph, bank 1 and 2 long term trims are +12 to +14 on Bank 1, short term spikes to 20%.

Indy mechanic wants to replace all injectors at a cost of $3000. He says a smoke test can’t be done (?) and wouldn’t be helpful. Did suggest a new fuel pressure regulator- says mine is running high. Also says that we can’t isolate which injectors might be bad.

You guys have any thoughts on this? Thanks.

 

[2001LC]

LT FT +12 to +14. Indicate engine running lean. To much air in fuel mixture. Keep in mind. LTFT is ECM working to correct STFT to ~0. Other times, may indicate fuel starvation. But low MPG, suggest: ECM is able to add fuel, in it's attempt to compensate for to much air in mix, as does STFT jump to +20.

1. First look very hard for vacuum leaks. Correct all. Lean condition is very often a vacuum leak.
2. Do a, by the book fuel pressure and leak down test. I'll note here. FP test, doesn't always reveal a condition I've found. Where fuel tank has contaminates. Namely iron, from old filling station with outdated iron storage tanks rust. I had one 2006, 250K miles, stock. Very clean a in top shelf condition end to after 4 years of me doing everything, but replacing fuel pump. It had a LTFT of ~+7. As a PM, we R&R fuel pump & filter. Found iron/rust in fuel tank, pump sock, fuel pump and fuel filter. Cleaned it all up. LT FT dropped to +2, STFT ~0. At altitude of 5,000 ASL.
3. Look at gas cap area. Is it mucky/grimy. You very likely will benefit, replacing Charcoal Canister and it's pre filter (06-07).
4. Inspect S.A.I. filter. If missing from view or someone installed a block-off kit. Do a compression test.

You can get a lot of benefit. Sending out fuel injector to be tested and cleaning. If any found bad flow rate or weak spray pattern. Target replace only those.
Note: Dead one, is very easy to test on vehicle. Simple disconnect one that a P030* DTC points to, see if RPM hold the same (dead) or drop (working).

Thread 'When to Clean or Replace fuel injectors'

Jan 14, 2016

Please post your experiences and thoughts on the subject.

I’ve been considering cleaning or even replacing all 8 fuel injectors, is this wasting time and money. I understand keeping fuel injector clean by adding a can of additive to the gas tank, now & then, is a good practice. This keeps them operating at peak performance, but for how long. When should we do more and what should be done. Do they weaken over time reducing performance or preform at peak until failure. I’ve read they’re good for 1 billion cycles, which I've read is ~350K miles. How about seals, should they be included...

• 2001LC
• Replies: 43
• Forum: 100-Series Cruisers

• 

I did lot of research, years ago. On the VVti engine P0430 & P0420 (CAT failure). Then to just have replacement CATs, fail.

1. First, never prolong idle. It loads the CAT. See: your OM.
2. Keep vehicle tuned.
3. Do my S.A.I filter mod.

I'd also try 2 cans of 44K in full tank of gas. With good oil and filters in engine. I do some high RPM runs (Italian tunes), after I've burned through most this tank of gas.
Then once low fuel light comes on plus ~10 miles normal driving. Which leaves 4 gallons in fuel tank. Add a can of Cataclean, and drive.. Do not let it sit with cataclean in tank. I like to carry a spare jerry can of gas. So I can run out the mixture of 4 gal gas and cataclean. Then fill gas tank with ~25 gallons. The drive and doing another high RPM run. This cleans fuel injector. Also intake ports, valve, pistons top, compression rings, spark plugs, A/F & O2 sensors and CATs

BTW: Do high RPM runs. At around 4,500 RPM. Drive on HWY ~ 5minutes to heat CATS. Then make your first High RPM run, for just 1 or 2 minutes. To fully heat CAT to max. But keep time short at first, incase CAT loaded with fuels/carbon. So That we don't ignite and burn up CAT. Then shift back up to D, and drive normal RPM for ~5 minutes, to cool CATs. Repeat for 3 to 5 minutes run., Then repeat for 10 minutes or more run. Cooks off carbo form CATs, like a selfclean oven.

 

[hikerfisher]

LT FT +12 to +14. Indicate engine running lean. To much air in fuel mixture. Keep in mind. LTFT is ECM working to correct STFT to ~0. Other times, may indicate fuel starvation. But low MPG, suggest: ECM is able to add fuel, in it's attempt to compensate for to much air in mix, as does STFT jump to +20.

1. First look very hard for vacuum leaks. Correct all. Lean condition is very often a vacuum leak.
2. Do a, by the book fuel pressure and leak down test. I'll note here. FP test, doesn't always reveal a condition I've found. Where fuel tank has contaminates. Namely iron, from old filling station with outdated iron storage tanks rust. I had one 2006, 250K miles, stock. Very clean a in top shelf condition end to after 4 years of me doing everything, but replacing fuel pump. It had a LTFT of ~+7. As a PM, we R&R fuel pump & filter. Found iron/rust in fuel tank, pump sock, fuel pump and fuel filter. Cleaned it all up. LT FT dropped to +2, STFT ~0. At altitude of 5,000 ASL.
3. Look at gas cap area. Is it mucky/grimy. You very likely will benefit, replacing Charcoal Canister and it's pre filter (06-07).
4. Inspect S.A.I. filter. If missing from view or someone installed a block-off kit. Do a compression test.

You can get a lot of benefit. Sending out fuel injector to be tested and cleaning. If any found bad flow rate or weak spray pattern. Target replace only those.
Note: Dead one, is very easy to test on vehicle. Simple disconnect one that a P030* DTC points to, see if RPM hold the same (dead) or drop (working).

Thread 'When to Clean or Replace fuel injectors'

Jan 14, 2016

Please post your experiences and thoughts on the subject.

I’ve been considering cleaning or even replacing all 8 fuel injectors, is this wasting time and money. I understand keeping fuel injector clean by adding a can of additive to the gas tank, now & then, is a good practice. This keeps them operating at peak performance, but for how long. When should we do more and what should be done. Do they weaken over time reducing performance or preform at peak until failure. I’ve read they’re good for 1 billion cycles, which I've read is ~350K miles. How about seals, should they be included...

• 2001LC
• Replies: 43
• Forum: 100-Series Cruisers

• 

I did lot of research, years ago. On the VVti engine P0430 & P0420 (CAT failure). Then to just have replacement CATs, fail.

1. First, never prolong idle. It loads the CAT. See: your OM.
2. Keep vehicle tuned.
3. Do my S.A.I filter mod.

I'd also try 2 cans of 44K in full tank of gas. With good oil and filters in engine. I do some high RPM runs (Italian tunes), after I've burned through most this tank of gas.
Then once low fuel light comes on plus ~10 miles normal driving. Which leaves 4 gallons in fuel tank. Add a can of Cataclean, and drive.. Do not let it sit with cataclean in tank. I like to carry a spare jerry can of gas. So I can run out the mixture of 4 gal gas and cataclean. Then fill gas tank with ~25 gallons. The drive and doing another high RPM run. This cleans fuel injector. Also intake ports, valve, pistons top, compression rings, spark plugs, A/F & O2 sensors and CATs

BTW: Do high RPM runs. At around 4,500 RPM. Drive on HWY ~ 5minutes to heat CATS. Then make your first High RPM run, for just 1 or 2 minutes. To fully heat CAT to max. But keep time short at first, incase CAT loaded with fuels/carbon. So That we don't ignite and burn up CAT. Then shift back up to D, and drive normal RPM for ~5 minutes, to cool CATs. Repeat for 3 to 5 minutes run., Then repeat for 10 minutes or more run. Cooks off carbo form CATs, like a selfclean oven.

Thanks very much. Interesting, a year and a half ago my Wyoming Toyota mechanic replaced my fuel pump due to contamination, and now my Oregon mechanic is telling me I;'ve got abnormally high fuel pressures (so he wanted to replace the fuel pressure regulator). I've got to put another 1200 miles on this car for a trip to CA and back, so I'll have to wait to further investigate.

Thanks again for the input.

 

[2001LC]

Thanks very much. Interesting, a year and a half ago my Wyoming Toyota mechanic replaced my fuel pump due to contamination, and now my Oregon mechanic is telling me I;'ve got abnormally high fuel pressures (so he wanted to replace the fuel pressure regulator). I've got to put another 1200 miles on this car for a trip to CA and back, so I'll have to wait to further investigate.

Thanks again for the input.

Was it the OEM fuel pump?

When fuel pressure to high. We replace fuel pressure regulator (FPR). R&R FPR a ~$110 part and 30 minutes. Less time, if engine cover off. It is the FPRs job, to keep pressure under 45PSI. (spe 38 to 44PSI)

From FSM fuel pressure test PDF attached, Step #2 (i) pressure test. :

i) Measure the fuel pressure. Fuel pressure: 265 to 304 kPa (2.7 to 3.1 kgf/cm 2 , 38 to 44 psi). If the pressure is high, replace the fuel pressure regulator.

If the pressure is low, check the fuel hoses and connections, fuel pump, fuel filter and fuel pressure regulator.

(j) Disconnect the intelligent tester from the DLC3.
(k) Start the engine.(l) Measure the fuel pressure at idle. Fuel pressure:265 to 304 kPa (2.7 to 3.1 kgf/cm 2 , 38 to 44 psi)(m).
Stop the engine.
(n) Check that the fuel pressure remains as specified for 5 minutes after the engine has stopped. Fuel pressure:147 kPa (1.5 kgf/cm 2 , 21 psi) or more If the pressure is not as specified, check the fuel pump, pressure regulator and/or injectors.

I follow FSM procedure. Except they way I tap into fuel rail. I've a faster way, by just tapping into line after filter.

 

[nissanh]

Are these true Denso? 4 O2 “sensors” from Denso.

Check for the O2 sensor voltages Sensor-1 on both banks: It should oscillate between 200 mV and 900 mV. How is the air flow sensor? OEM or Aftermarket? Invest in a good scanner that has a graphing function. There could be various reasons why trims are so high.

I saw Kingbolan 7 is at about $290 and it can do most scans.

You can unplug both O2 sensors and check new trims. The system should go to bias voltage output from the O2 sensors.

 

[hikerfisher]

Was it the OEM fuel pump?

When fuel pressure to high. We replace fuel pressure regulator (FPR). R&R FPR a ~$110 part and 30 minutes. Less time, if engine cover off. It is the FPRs job, to keep pressure under 45PSI. (spe 38 to 44PSI)

From FSM fuel pressure test PDF attached, Step #2 (i) pressure test. :

i) Measure the fuel pressure. Fuel pressure: 265 to 304 kPa (2.7 to 3.1 kgf/cm 2 , 38 to 44 psi). If the pressure is high, replace the fuel pressure regulator.

If the pressure is low, check the fuel hoses and connections, fuel pump, fuel filter and fuel pressure regulator.

(j) Disconnect the intelligent tester from the DLC3.
(k) Start the engine.(l) Measure the fuel pressure at idle. Fuel pressure:265 to 304 kPa (2.7 to 3.1 kgf/cm 2 , 38 to 44 psi)(m).
Stop the engine.
(n) Check that the fuel pressure remains as specified for 5 minutes after the engine has stopped. Fuel pressure:147 kPa (1.5 kgf/cm 2 , 21 psi) or more If the pressure is not as specified, check the fuel pump, pressure regulator and/or injectors.

I follow FSM procedure. Except they way I tap into fuel rail. I've a faster way, by just tapping into line after filter.
View attachment 4068036View attachment 4068035

Yes, it was OEM fuel pump.

Are these true Denso? 4 O2 “sensors” from Denso.

Check for the O2 sensor voltages Sensor-1 on both banks: It should oscillate between 200 mV and 900 mV. How is the air flow sensor? OEM or Aftermarket? Invest in a good scanner that has a graphing function. There could be various reasons why trims are so high.

I saw Kingbolan 7 is at about $290 and it can do most scans.

You can unplug both O2 sensors and check new trims. The system should go to bias voltage output from the O2 sensors.

awesome- thanks. I’ll check this out

 

[2001LC]

Keep in mind. Your running rich. ECM is working hard to correct, but still to rich as confirmed by MPG. If fuel pressure test was done correct and pointed to FPR. I'd not wait. R&R ASAP.

Running to rich, cylinder temp is lower. Which shouldn't be damaging. 3 times over 20% FT, you'll get DTC (CEL). Likely be a flashing CEL. You must shut down engine.

CAT are getting excessive fuel/carbon. To much and they may ignite and burn them up. While driving on HWY, likely burn off fuel in CATs, fast enough, to not accumulate. But idling, stop & go and slow driving. They may overload with fuel/carbons and ignite.

R&R FPR is very easy. You can do at side of the road. Only two tools needed. 10mm socket on extension and pliers. Save a few drops of gasoline, from old FPR. To wet new O-ring.

 

[hikerfisher]

Keep in mind. Your running rich. ECM is working hard to correct, but still to rich as confirmed by MPG. If fuel pressure test was done correct and pointed to FPR. I'd not wait. R&R ASAP.

Running to rich, cylinder temp is lower. Which shouldn't be damaging. 3 times over 20% FT, you'll get DTC (CEL). Likely be a flashing CEL. You must shut down engine.

CAT are getting excessive fuel/carbon. To much and they may ignite and burn them up. While driving on HWY, likely burn off fuel in CATs, fast enough, to not accumulate. But idling, stop & go and slow driving. They may overload with fuel/carbons and ignite.

R&R FPR is very easy. You can do at side of the road. Only two tools needed. 10mm socket on extension and pliers. Save a few drops of gasoline, from old FPR. To wet new O-ring.

Awesome- thanks for the tips. I've ordered an OEM FPR from my local Toyota dealer- here tomorrow morning, along with a new OEM PCV valve and hose. I should be able to get these installed before I put 2000 miles on my LX starting this Saturday.

 

[hikerfisher]

Are these true Denso? 4 O2 “sensors” from Denso.

Check for the O2 sensor voltages Sensor-1 on both banks: It should oscillate between 200 mV and 900 mV. How is the air flow sensor? OEM or Aftermarket? Invest in a good scanner that has a graphing function. There could be various reasons why trims are so high.

I saw Kingbolan 7 is at about $290 and it can do most scans.

You can unplug both O2 sensors and check new trims. The system should go to bias voltage output from the O2 sensors.

Thanks. Are the sensor voltages available on a half decent OBDII reader, or do I need Techstream? Thanks.

 

[baltistyle]

@2001LC

In that it is both banks, I dont see Maf mentioned. Any chance op has an issue there?

Also nice to see that you use and like cataclean when needed.

 

[2001LC]

@2001LC

In that it is both banks, I dont see Maf mentioned. Any chance op has an issue there?

Also nice to see that you use and like cataclean when needed.

MAF issues effect both banks. A bad MAF will produce a DTC and CEL, in most cases. Driving with a bad one, can kill CATS fast.
A weak or dirty, MAF. "May" not produce a CEL or DTC. They may test within spec, even after cleaning. I have found; Replacing old MAF with new OEM. Often yields benefits, seen in fuel trim and MPG.

Keep in mind in OP case. His Fuel pressure was tested as high and diagnosed as FPR. FPR musty be replaced as a first step.

Cataclean, Sledge hammer, etc.. Are paint thinners, plus. These companies claim, to test amount and procedure as safe.
You'll find YouTubes, of just paint thinner used in gas tank. But how much is safe, do they do as good! IDK.

I've used in one 4.7L VVTi:

1. 2 cans 44K to full tank. Run that tank down.
2. Chevron Techron. Next tank.
3. Seafoam fogger. I start with 1/3 can, hot engine, shut engine off as soon as the 1/3 can in. Then let cool overnight. The drive on HWY. Stop and add 1/3 can, shut down 10 minutes to soak, continue HWY drive. Stop add last 1/3 can, have lunch letting engine cool down for ~1 hr.
4. Add Cataclean

Doing "High RPM runs" Frequently during above cleaning chemical adds.

Then, pulled intake manifold. Finding the intake ports of heads. Look like new. Void of the normal gunk lining the walls of ports.
Take Fuel Injector out, and sent off to Fuel Injector Specialist to test. They tested in perfect condition, pre cleaning.
But unfortunately, it did not correct the PO430 (BK2 CAT). BK1 CAT, had already been replaced. After all brough back to factory spec. CAT was replaced and has been fine. That was ~5 years ago.

But note: This was the vehicle I found the #1 cause. Of the 06-07 4.7L VVTi, taking out CAT, then replacement CAT also.

Thread 'S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert!'

Dec 11, 2021

We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW!

I've a very easy and cheap WORK AROUND. You are going to love this

This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the 2006 & 2007 100 series Toyota Land Cruiser & Lexus LX470 manufacture in Japan for the USA market.
It also applies to all 4.7L 2UZ-fe VVTi such as in the: GX470, 4Runner, Sequoia, etc. Every 2UZ-fe 4.7L VVT engines, S.A.I. filter will fail. AND then get CAT...

• 2001LC
• Replies: 134
• Forum: 100-Series Cruisers

• 

I've advised other to use 44k, HIGH RPM runs, then Cataclean. It did clear P04--. They clogged CAT, by prolonged idling, along with slow stop and go driving, without getting on HWY.

Awesome- thanks for the tips. I've ordered an OEM FPR from my local Toyota dealer- here tomorrow morning, along with a new OEM PCV valve and hose. I should be able to get these installed before I put 2000 miles on my LX starting this Saturday.

PCV valve on 03-07, are a bear to get off. The threads are sealed, with red. I use a large wrench that is good a sung fit. I then put a leverage bar extension on wrench, to break it free.

Make sure all vacuum hoses (PCV hose on BK2, vacuum hose on both banks, and the duel idle up control vacuum hoses), are also in good condition.

 

[baltistyle]

MAF issues effect both banks. A bad MAF will produce a DTC and CEL, in most cases. Driving with a bad one, can kill CATS fast.
A weak or dirty, MAF. "May" not produce a CEL or DTC. They may test within spec, even after cleaning. I have found; Replacing old MAF with new OEM. Often yields benefits, seen in fuel trim and MPG.

Keep in mind in OP case. His Fuel pressure was tested as high and diagnosed as FPR. FPR musty be replaced as a first step.

Cataclean, Sledge hammer, etc.. Are paint thinners, plus. These companies claim, to test amount and procedure as safe.
You'll find YouTubes, of just paint thinner used in gas tank. But how much is safe, do they do as good! IDK.

I've used in one 4.7L VVTi:

1. 2 cans 44K to full tank. Run that tank down.
2. Chevron Techron. Next tank.
3. Seafoam fogger. I start with 1/3 can, hot engine, shut engine off as soon as the 1/3 can in. Then let cool overnight. The drive on HWY. Stop and add 1/3 can, shut down 10 minutes to soak, continue HWY drive. Stop add last 1/3 can, have lunch letting engine cool down for ~1 hr.
4. Add Cataclean

Doing "High RPM runs" Frequently during above cleaning chemical adds.

Then, pulled intake manifold. Finding the intake ports of heads. Look like new. Void of the normal gunk lining the walls of ports.
Take Fuel Injector out, and sent off to Fuel Injector Specialist to test. They tested in perfect condition, pre cleaning.
But unfortunately, it did not correct the PO430 (BK2 CAT). BK1 CAT, had already been replaced. After all brough back to factory spec. CAT was replaced and has been fine. That was ~5 years ago.

But note: This was the vehicle I found the #1 cause. Of the 06-07 4.7L VVTi, taking out CAT, then replacement CAT also.

Thread 'S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert!'

Dec 11, 2021

We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW!

I've a very easy and cheap WORK AROUND. You are going to love this

This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the 2006 & 2007 100 series Toyota Land Cruiser & Lexus LX470 manufacture in Japan for the USA market.
It also applies to all 4.7L 2UZ-fe VVTi such as in the: GX470, 4Runner, Sequoia, etc. Every 2UZ-fe 4.7L VVT engines, S.A.I. filter will fail. AND then get CAT...

• 2001LC
• Replies: 134
• Forum: 100-Series Cruisers

• 

I've advised other to use 44k, HIGH RPM runs, then Cataclean. It did clear P04--. They clogged CAT, by prolonged idling, along with slow stop and go driving, without getting on HWY.


PCV valve on 03-07, are a bear to get off. The threads are sealed, with red. I use a large wrench that is good a sung fit. I then put a leverage bar extension on wrench, to break it free.

Make sure all vacuum hoses (PCV hose on BK2, vacuum hose on both banks, and the duel idle up control vacuum hoses), are also in good condition.

As always, thank you for a nice complete explanation. I made the statement about chemicals because I too am a fan of proper use of chemicals without fear. My other car is a very high dollar AMG engine and people are very afraid in that world to use chemicals so I like to try to give them real world examples of my success.