Help With My Daily Grocery-Getter

[FR-S2GT86]

So several of you guys here have all helped me in the past with my FR-S and I have returned the favor with a few DIY write-ups, and adding comments to many troubleshooting issues over the years. There are some excellent mechanics and all-around DIY car enthusiasts here and we all seem to be able to come together with ideas in order to solve problems with the cars we like to drive. With that said, I have recently been trying to track down an issue in my '00 Solara with the 1MZ-FE non-VVTi V-6 and I'm hoping some of you with experience with these engines may be able to offer some advice that I have not yet thought of.

I'll explain what it is doing and what I have done so far:

First, the engine in this non-California model is 100% stock, mated to the 4-speed automatic transmission utilizing a MAF sensor system only (no MAP sensor), and three Oxygen sensors (no AFR sensors) with single catalytic converter. There have been no codes pop up at all. This is telling me that the issue that I am having is within the tolerances of the ECU to be able to compensate for. Nevertheless, the engine has over 187,000 miles on it now and I would expect there to be some issues. I want to keep this car running for as long as possible since it is in such great shape and I'd like to keep it that way for many years to come. I am actually performing some restoration on it with all new OEM suspension and brake components along with the fuel system maintenance I'm doing, with more work to come.

So the issue is, during low-speed and higher-speed driving, my LTFTs on BOTH banks seem normal, running between 0 and +3%. This indicates to me there is proper fuel pressure and no injector fouling. However, when I stop and allow the engine to idle for a while, the front bank ONLY seems to begin to run slightly lean and the LTFT for it starts to increase and run between +3 and +6%. The rear bank continues to run as it was. To me, this is indicating the presence of a tiny vacuum leak somewhere on that front bank. If it were a vacuum leak that was common to both banks, such as any point from downstream of the MAF sensor on up to the intake manifold, I would expect that the LTFTs for BOTH banks would be affected and I would see increases to both in response, which is not the case here. I would add that there have been no misfires, the engine idles normally between 730 to 780 RPM and seems to run smooth as silk at all RPMs.

Before looking for any vacuum leaks, I replaced the non-OEM B2,S1 Oxygen sensor, which was installed by a previous mechanic, with a Toyota OEM O2 sensor in order to rule it out as being the culprit. I did that yesterday along with sealing a couple of exhaust leaks that have plagued this car since getting a custom dual exhaust and replacement flex pipe installed several years ago. I then reset the ECU to begin data logging again with a fresh ECU memory. The same issue remains and seems to be pointing to a tiny vacuum leak somewhere on that front bank.

Before tearing into that front bank, I wanted to make sure there were no other issues upstream, so this morning I decided to disassemble the intake up to the throttle body seeing how there was an oily build-up on the air intake tubing in the general area where the crankcase gasses of the PCV system from the front bank valve cover are piped into. This revealed that one of the clamps on the air intake tubing, after the MAF sensor and before the throttle body, was loose and the oil residue from the PCV system was leaking at that point. I also found cracked hose ends connecting the canister purge valve to the air filter housing, which I have addressed and should no longer be leaking. I am currently cleaning the oil mess up and will be making sure all of this is properly and tighly reinstalled. Afterwards, I will be resetting the ECU and taking the car out for another test drive and idle check. Any other intake or PCV system leaks found up to the throttle body will be addressed today.

If anyone has any ideas of what to look for specifically that could cause the issue I described above that would not be addressed with what I am doing today, please chime in. I would greatly appreciate your advice. For now, I am heading back into the garage to finish and will check back here and include an update after the test drive and data logging.

Thanks in advance.

[Lantanafrs2]

Leave it alone. It will let you know if there's a problem. You'll probably get another 70k out of it.

[NoHaveMSG]

+3-6% ltft isn't too bad I would be that worried about it.

[FR-S2GT86]

Originally Posted by Lantanafrs2

Leave it alone. It will let you know if there's a problem. You'll probably get another 70k out of it.

I think the previous owner had that same attitude with the suspension on this car which is why it was so bad when I finally got it. One can get used to bad suspension if it goes bad over a lengthy period of time. I'm not going to let something similar happen to the fuel system, I'd rather catch it early. I'd much rather get another 180,000 miles out of this car.

Update:

So with all of the common vacuum leaks fixed by replacing a couple of hoses and properly tightening all the clamps, it seems I have improved the LTFTs on both banks by about 1%, so now Bank 1 is running between 0 and +2% and Bank 2 is running between +2 and +5% at idle. Admittedly, not much of an improvement, but at least everything is clean and leak-free pre-intake manifold.

About 30,000 miles ago, along with a water pump and timing belt, I had the spark plugs, plug wires, valve cover gaskets and coolant crossover tube replaced by my old mechanic (who has since retired) requiring removal of the intake. With all that done, I'm pretty sure they pulled the injectors out and reinstalled them. I think from this point, I'll try smearing some vacuum grease around each of the three Bank 2 injectors where they enter the manifold to test if any of the O-rings are not sealing properly before pulling them out for a visual inspection.

[FR-S2GT86]

Originally Posted by NoHaveMSG

+3-6% ltft isn't too bad I would be that worried about it.

If it's anything other than injector O-rings, I will probably just let it go.

[Spuds]

I don't really worry about anything +-10% at idle fwiw.

[FR-S2GT86]

Results after pulling those front (Bank 2) injectors out, cleaning them, replacing the O-rings and grommets and reinstalling:



Bank 2 LTFT is now running at 0.0%, perfect!

The rear bank (Bank 1) is running -3.9%, slightly rich.

I noted that the grommets were hardened from being so old but the O-rings seemed nice and pliable with no damage. I expect I had a small vacuum leak at one of the grommets.