This was performed in the last 1k miles;

- Did VPS fuel treatment
- Cleaned air intake including throttle body and intake manifold
- Replaced vacuum lines, one injector that was cracked
- Replaced PCV valve
- Installed new intake gaskets
- Replaced mass air flow meter

After replacing the fuel pump it seems like it’s a little worse as now it won’t staying running very long.

 

This is what is in TIS for P1170:

 

Code definitions don't always point to what's wrong. There are overlaps in parameters and codes on how the ECM monitors and produces codes. The P1170 code is for fuel trim but most of the time it's not an actual injector issue, let alone 7 all at once. Another member had VERY similar codes to the OP here (P0172/P0175 and P1170) and his fix may have been cleaning his MAF and servicing some points of vacuum leaks like the PVC hoses. P1170 code help w/ freeze frame data - ClubLexus - Lexus Forum Discussion

I used to work on Nissans where a ton of them would throw MAF codes P0101. We replaced many sensors (at first) and had the cars come back. It turns out most of them were actually vacuum leaks. The ECU doesn't know that it's not the MAF that's faulty, it just knew (according the Nissan programming) that air/fuel were wrong, but it was measured through the MAF, throwing a code.

A Toyota/Lexus specific example is the ABS light. I can't count how many times I've seen the ABS light come on in tandem with a PXXX code. The ABS light had nothing to do with the P codes, and once the misfire or whatever was fixed, the ABS code would go away. Just how Toyota/Lexus are wired

 

Code definitions rarely point directly to the source of the issue. But in this case, the dealership is telling him they're going to pursue this by following the book and the manual says replace a bunch of parts. That's where this is getting weird.

Vacuum leak opportunities in this engine are not many and finding them isn't rocket science. Vacuum leak issues are accompanied with MAF efficiency codes (AMHIK), not just lean bank 1 and 2 with P1170. I am very certain if there were a significant vacuum leak, like the cracked PCV hose I had, there would be MAF efficiency codes as well as there were with mine.

At this point, it's sounding a lot like a fuel pressure issue. When I had the fuel lines inverted on mine after the valve lash inspection, I got fuel pressure codes and the engine's operation was very similar to what the OP is describing. I'm also still unconvinced the issue isn't a bad connection in the harness.

The one thing I wouldn't do is replace all the injectors. That's stupid expensive, and unlikely to fix the root cause IMHO.

 

There are many places for this engine to have vacuum leaks. And while it’s not rocket science, very often simple smoke tests are not even performed. Without this and/or if not diligent enough (or not able to see due to a particular bend, lighting, etc) may result in a vacuum leak never found.

I suppose it’s possible they pinched a harness or something electrical. It’d have to be bad enough to cut power indefinitely or intermittently (somehow) to have an affect on fueling. He’s essentially getting 2x lean codes and a third code which is another fuel trim code. Again I don’t believe this to be fuel related because he said the car acts up when it’s under the most vacuum - low throttle to idle. A vacuum leak disrupts this.

Not sure if anything in Techstream pointed the techs to think all injectors are bad or if they’re just looking at TIS definitions which would be the wrong move imo.

 

Meh. Doesn't sound like you've worked on a stock 2JZ-GTE. This engine doesn't have even 10% of the pressure/vacuum hoses that engine does. Absent MAF efficiency codes, the likelihood of a large vacuum leak is just about zero.

Not all techs really understand what causes problems like this. I still think it's electrical/electronic, not vacuum based on my direct experience with these engines.

 

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Yeah I’m not going to compare this to other engines. It still has a lot of vacuum lines. Diagrams show this, and a smoke test certainly does too. You have evap lines running from the tank, various purge valves, it goes on and on.

Every time I’ve directly worked on these or any Toyota/Lexus with P017X codes it’s been a vacuum leak. Which are two codes that he has. Whether or not its thought to be related to the P1170 code is a different story, even though the two threads I’ve posted with that code were solved via vacuum line fixing.

A smoke test would just-about rule out a vacuum leak issue.

If it’s electronic based, hopefully something in Techstream shows anything related to that. Otherwise you’re going to be basically doing the VP job again to go back over anything that was done wrong, and/or replacing stuff blindly till it’s fixed.

 

I appreciate all the suggestions and feedback. It’s back at the shop and fingers crossed the problem and solution will be found.

I’ll update as I find out in case anyone else has similar issue in the future. Nothing worse than having the discussions and never finding out the answer…..

 

I'd smoke test the engine. I found a very small vacuum leak at my throttle body/intake elbow connection that was causing terrible drivability issues. I would not have found the leak without a smoke test.

 

Fingers crossed it has been resolved.....they found that when the dealership replaced the intake gaskets and repaired the valley plate that neither one was done correctly and there were leaks. It has been repaired and (so far) is running very well.

Again, I appreciate all the feedback and look forward to learning more through this forum.

 

Glad to see it was resolved via fixing vacuum lines like I suspected. Enjoy!