2UZ-FE High Long Term Fuel Trims (1 Viewer)

[Rednexus]

Definitely sounds like the connection is ok after first plugging in and then looses some continuity after a few minutes. The short terms will try to cancel out the long terms until the grody connection settles back to what the computer has adapted to. Could be weak pins, corrosion, etc. New MAF connectors are cheap enough it's worth a go.

Just some evidence for the jury—a Subaru forum where they had similar issues, but with mixtures reading rich (like what mine is currently doing) until the plug was fiddled with:

https://legacygt.com/forums/showthread.php/faulty-maf-sensor-connectori-255914.html?s=0b2d95f954b8053c0e73d4186c35f19c&

When installing the new plug I personally wouldn't use dielectric grease of any sort. Bare clean metal is the best for these highly-sensitive contacts. Some Deoxit D5 is the most I'd put on something like that.

I found and ordered new plug for $24 shipped from Ballanger Motorsports. eBay was the only other place I could find one. Looks like it's a common plug with lots of Toyotas, a few Mazdas, and Duramax Diesels of all things. I'll clean the grease out of the MAF before I install it. This also gives me the opportunity to lengthen and re-route the MAF harness, as it's kind of laying on top of the aFe CAI and looks a bit janky.

Thanks for the tip on the plug, I'll report back when I get it spliced in.

 

[Rednexus]

So a few updates:

1. A new aFe CAI tube showed up at my door last week, after I had emailed them. Weird because they never told me they shipped one, and I talked to aFe on the phone the same day and they didn't mention it was showing up! I replaced the tube and have similar fuel trims as before.
2. The new MAF connector and pigtail came in yesterday. I spliced it into the OEM harness with some heat shrink butt connectors. It's definitely more secure on the MAF than the old one. LTFTs are reducing slightly, but not much (still in the 15-17 range but better than the 20+ I was getting, albeit with just a couple of days of driving). Oddly, the MAF plug for the '07 GX is exactly the same as our '14 Subaru Outback.
3. I have not thrown a PO101 code in a week of driving, since swapping out the new aFe CAI tube.

So, short of swapping the OEM CAI back on, it seems like the aFe CAI design must be the culprit now. It flows more air than stock or is more turbulent, causing the O2 sensors to correct and add more fuel. Despite that, the 2UZ-FE runs great, gets good gas mileage (still hitting 19-20 mpg on the highway), and has more power than stock. The obvious solution is that these engines really need a tune with a CAI....although the ECU is able to correct for the MAF by upping the fuel trims and it's possible to NOT throw a CEL with these CAIs, it's probably running a bit rich at WOT since the closed-loop WOT air/fuel tables use the LTFTs as a baseline. Orange Virus has cracked the 2UZ-FE ECU and has a beta testing tuning software for it that allows the MAF tables to be adjusted. The GX will be getting headers and a catback this spring, so if I do tune it, it will wait until that is complete.

 

[mitchjohnson000]

I don't see the point of using an aftermarket intake on a 2UZ-FE truck application. Unless you adding FI a tune will not improve the driving experience. Toyota's base tune has actual R&D behind it. Changing the intake or tune defeats the main purpose of the GX/100 series, reliability.

Having a fuel trim of +17% is pretty lean (my LTFT are 3% across both banks), I'd be more concerned about the cooling system than exhaust mods.

 

[Rednexus]

I don't see the point of using an aftermarket intake on a 2UZ-FE truck application. Unless you adding FI a tune will not improve the driving experience. Toyota's base tune has actual R&D behind it. Changing the intake or tune defeats the main purpose of the GX/100 series, reliability.

Having a fuel trim of +17% is pretty lean (my LTFT are 3% across both banks), I'd be more concerned about the cooling system than exhaust mods.

It has better midrange torque, downshifts less on hills, and gets around 0.5-2 mpg better with the CAI than stock. It also runs a consistent 185 degrees and right at 14.7:1 AFR with the CAI. So I can attest that it has improved the driving experience, in addition to sounding much better.

 

[Eicca]

What are your short terms doing with the new plug?

 

[mitchjohnson000]

Nice, can't say I've ever heard of a N/A 2UZ with a wideband. Sounds like you are missing out by not having some 12 hole injectors.

My experience with 12 hole injectors. Awesome!

After following this thread Anyone ever installed bigger injectors? i decided to pull the trigger on a set of 12 hole injectors from Dirty Deeds. All results are positive. Improved throttle response at 20-80 % pedal position, noticeable improvement in top end pull on the highway. All this and i...

forum.ih8mud.com

 

[04UZJ100]

So the aftermarket CAI caused all issues as I suggested. ....

 

[Rednexus]

What are your short terms doing with the new plug?

-4 to -7 or so, but I need to put some more miles on it to see how they change. It could improve a bit more.

So the aftermarket CAI caused all issues as I suggested. ....

Did you read the thread and my update? The CEL issue was due to a faulty MAF plug. Fuel trims are indeed due to the CAI but the truck runs great and is now capable of getting 20 mpg or better. I consider that a success and would re-install the CAI.

 

[Eicca]

-4 to -7 or so, but I need to put some more miles on it to see how they change. It could improve a bit more.

If you didn't reset the ECU as part of this process I'd recommend that too. Your MPG may drop for a bit until the re-learning process is complete.

 

[OwnerCS]

Good thread here. Last weekend I used my Scangauge to check fuel trims on the interstate. I was cruising along the interstate at 60-65 MPH.

The Long Term Fuel trim stayed on zero. I thought something was wrong with it because I got a zero reading. Then I accelerated (changed speed) and it did move to a +1 and quickly back to zero.

Short team fuel trim was more active depending on accelerator movement. I think it would hang around 0 while cruising while jumping up to 3 (average) or more reading depending on acceleration.

No complaints about fuel mileage or issues at ~240.000 miles. I replaced all O2 sensors roughly 5,000 miles ago and new plugs have been in for 1,500 miles with Denso recommended. I am a stickler about having squeaky clean new O2 sensors and clean MAF when I buy a used vehicle and start the baseline process.

 

[rancejunge]

Good thread here. Last weekend I used my Scangauge to check fuel trims on the interstate. I was cruising along the interstate at 60-65 MPH.

The Long Term Fuel trim stayed on zero. I thought something was wrong with it because I got a zero reading. Then I accelerated (changed speed) and it did move to a +1 and quickly back to zero.

Short team fuel trim was more active depending on accelerator movement. I think it would hang around 0 while cruising while jumping up to 3 (average) or more reading depending on acceleration.

No complaints about fuel mileage or issues at ~240.000 miles. I replaced all O2 sensors roughly 5,000 miles ago and new plugs have been in for 1,500 miles with Denso recommended. I am a stickler about having squeaky clean new O2 sensors and clean MAF when I buy a used vehicle and start the baseline process.

Did you install headers yet? I am going to put my long tube Doug Thorley headers on soon with magnaflow cat back. Also looking to put the MAP-ECU 3 piggyback in. I am tracking the MPG to see the results of the mods.

 

[Rednexus]

Since this thread was resurrected, I figured it would be good to give an update.

I've had no issues with MAF-related CEL's since replacing the MAF and MAF plug in early 2021. Since then I installed a set of DT LT headers and installed a SAIS bypass (including removing the SAIS tubes). This gave the GX quite a bit more power and it ran great.

Regarding the LT FT's, they stopped being crazy-high after fixing the MAF plug, but were still all over the place, and would oscillate from around 0 to 12+. I noticed that the high positive LT FT's would sometimes appear after running a tank of discount, non-top tier gas through the GX (which I did fairly often when gas was $4.50+ a gallon), and the GX seemed light on power. This would usually fix itself after resetting the ECU.

Earlier this summer I went ahead and replaced both upstream O2 sensors with new Denso units, just due to them being 15 years old. This seemed to stabilize the LTFT's. Now they are around 0 to +5, depending on engine speed/ambient air temp/etc. I don't ever expect them to be 0 consistently as my engine is no longer stock with the CAI and headers. I've ran some cheaper gas through it since then, which sometimes does seem to degrade performance, but the GX will go back to running normal on the next tank without resetting the ECU.

Overall....replace your O2 sensors. They don't last forever. Mine were definitely a bit slow/off. The GX also gets a bit better MPG towing with the new sensors (it did not change much unloaded).

 

[OwnerCS]

Did you install headers yet? I am going to put my long tube Doug Thorley headers on soon with magnaflow cat back. Also looking to put the MAP-ECU 3 piggyback in. I am tracking the MPG to see the results of the mods.

Still running stock headers. The only thing new that could have had an impact installed during the past few months is coils and vacuum hoses. Also, I did install a used MAF that I picked up from a part out because the original started to show some strange behavior.

 

[J1000]

Since this thread was resurrected, I figured it would be good to give an update.

I've had no issues with MAF-related CEL's since replacing the MAF and MAF plug in early 2021. Since then I installed a set of DT LT headers and installed a SAIS bypass (including removing the SAIS tubes). This gave the GX quite a bit more power and it ran great.

Regarding the LT FT's, they stopped being crazy-high after fixing the MAF plug, but were still all over the place, and would oscillate from around 0 to 12+. I noticed that the high positive LT FT's would sometimes appear after running a tank of discount, non-top tier gas through the GX (which I did fairly often when gas was $4.50+ a gallon), and the GX seemed light on power. This would usually fix itself after resetting the ECU.

Earlier this summer I went ahead and replaced both upstream O2 sensors with new Denso units, just due to them being 15 years old. This seemed to stabilize the LTFT's. Now they are around 0 to +5, depending on engine speed/ambient air temp/etc. I don't ever expect them to be 0 consistently as my engine is no longer stock with the CAI and headers. I've ran some cheaper gas through it since then, which sometimes does seem to degrade performance, but the GX will go back to running normal on the next tank without resetting the ECU.

Overall....replace your O2 sensors. They don't last forever. Mine were definitely a bit slow/off. The GX also gets a bit better MPG towing with the new sensors (it did not change much unloaded).

I was going to suggest that higher than normal levels of ethanol in the fuel could cause that. During the price surges earlier this year people were claiming all over the country gas smelled weird and some people measured 40% ethanol in gas that was labeled 10% ethanol.

Two things with CAIs that have oiled air filters: the oil can get on the MAF and cause issues so you should clean it regularly and also if you don't oil it regularly they don't filter very well.

 

[rancejunge]

Anyone know if these rods on Ebay are ok? TOYOTA 4.7L 2UZFE LANDCRUISER/TUNDRA HIGH PERFORMANCE H BEAM RODS 5.748" | eBay - https://www.ebay.com/itm/401579122799

 

[Rednexus]

I was going to suggest that higher than normal levels of ethanol in the fuel could cause that. During the price surges earlier this year people were claiming all over the country gas smelled weird and some people measured 40% ethanol in gas that was labeled 10% ethanol.

Two things with CAIs that have oiled air filters: the oil can get on the MAF and cause issues so you should clean it regularly and also if you don't oil it regularly they don't filter very well.

E10 is mandated for 87 octane in MO, unfortunately, which is what I've been running since fuel crested $2.00/gallon. The Top Tier fuel that I try to buy usually causes no issues, it's the discount stations (who perhaps are getting that higher ethanol fuel delivered!). My CAI is a aFe oil-less model that gets washed often, so no issues there.

One other potential issue could be my 15-year old injectors. I am going to pull them and overnight them to InjectorRX for a rebuild and flow testing later in December. I do get a bit of side-to-side difference in fuel trims (bank 2 is usually 2-3 percent higher than bank 1), perhaps that is the reason.

 

[Jimij]

I don't see the point of using an aftermarket intake on a 2UZ-FE truck application. Unless you adding FI a tune will not improve the driving experience. Toyota's base tune has actual R&D behind it. Changing the intake or tune defeats the main purpose of the GX/100 series, reliability.

Having a fuel trim of +17% is pretty lean (my LTFT are 3% across both banks), I'd be more concerned about the cooling system than exhaust mods.

Why the Cooling system? I have very high Lyft that seems persisteant after changing almost everything I could except the exhaust manifolds.I am too scared of snapping a bolt.

It throws po171, bank 1. Changing MAf maf and o2 sensors, as well as smoked out the vacuum leaks. All of which helped, but still very high ltft, at low engine loads.

I do have a spare 100, written off by insurance, but has everything. Plan is to take that engine out nd rebuild it with den thorly headers to fit the possible exist manifold leak in bank 2.

But back to your comment, sorry for the essay, why cooking?