Update on the sluggish accel issue:
The TPS now reads exactly at .44

Timing was 5 degrees off and using a timing light I got it at 15 on the money.

IAC duty cycle remains at 10%

Oxygen sensors seem to be getting worse. Bank 1 is much less active even under acceleration so I want to get that taken care of ASAP. HOWEVER, I see that they're situated on the dreaded bungs. This car has much less rust than others that I've worked on but I have not had a single positive experience with these nuts TBH. the position they're in is also concerning....

As for the injectors apparently I had given the subharmess a once over already. I noticed that the pins had been scrubbed and resistance was fine.

Overall the car is much more responsive. It no longer crawls from a stop but as you can imagine the acceleration is still severely lacking sometimes. When it works properly it does not fail to put a smile on my face. I'm almost there in terms of performance. I can feel it.

I found the O2 sensors to be surprisingly easy to replace from under the hood. An O2 sensor socket on a long extension, going vertically down from the back corner of the valve covers. Soak them with a good penetrating oil (WD40 is not a penetrating oil - use PB Blaster or Kroil) a few days ahead of time.

The ohm test I mentioned, was measuring the resistance of the injector coils themselves. You can do that through the harness to avoid pulling the plenum.

No1Dad wrote: ↑

Thu Sep 01, 2022 9:28 am

Update on the sluggish accel issue:
1)The TPS now reads exactly at .44

2)Timing was 5 degrees off and using a timing light I got it at 15 on the money.

3)IAC duty cycle remains at 10%

4)Oxygen sensors seem to be getting worse. Bank 1 is much less active even under acceleration so I want to get that taken care of ASAP. HOWEVER, I see that they're situated on the dreaded bungs. This car has much less rust than others that I've worked on but I have not had a single positive experience with these nuts TBH. the position they're in is also concerning....

As for the injectors apparently I had given the subharmess a once over already. I noticed that the pins had been scrubbed and resistance was fine.

Overall the car is much more responsive. It no longer crawls from a stop but as you can imagine the acceleration is still severely lacking sometimes. When it works properly it does not fail to put a smile on my face. I'm almost there in terms of performance. I can feel it.

1) good
2) smart to use timing light. Remember, your scan tool doesn't know where the base timing is set. That's why you use the light. Most scan tools I've seen quote 15deg on the screen when the ECU is calling for zero degrees of timing adjustment. The scan tools assume the user has set the base idle to 15, and "matches" that. then, as the ECU adds or subtracts the timing, the scan tool should match. So if your scan tool is reading 5 deg even when your base timing is set to 15, it sounds like something is telling the ECU to take out 10 deg of advance.
3) good, but.....a lot of scan tools I've seen say 10% duty even when it's zero. like 10% is the lower limit from the ECU mapping table. Which is why I suggested 11-15%, to force it off the lower stop.
Verify that when you slap it in gear, the IAC duty jumps up (20-ish percent). same with AC switched on. It' should run a higher duty to keep the revs at about 650 at idle when you put on the loads of AC/Alternator charging/drive gear.
4) as others have said, replacing is not too bad on the G50, just remember they are unforgiving if you round off the hex corners, so take your time and soak them as suggested, and have a TIGHT fitting crowfoot on there. When you say "much less active under acceleration", I would expect the O2s to both go lean when you smack the pedal, and maybe eventually the injectors will richen up enough to come out of O2 lean saturation as you get close to redline. And, of course, when you let off the throttle, they will peg rich until the fuel cutoff smooths things out. I suggest checking the rapid cycling of lean-->rich-->lean etc. under part throttle cruise, with constant throttle position, but not really accelerating or decelerating. THAT is where you should see the rapid cycling.

With hot boy summer at a close this vehicle has once again been put on the back burner.

I finally had a free moment and decided to check for vacuum leaks. I spent a while spraying the the plenum and while the graph was spiking I could not find the sweet spot. I was having a hard time tracking it down and was hyper focusing on the lower intake figuring it would be something that I had done wrong. I eventually smoked the intake and found the culprit to be this circle thing that I assume is part of the EGR system.


The vehicle still does not have the launch off the line that I'm craving but it no longer feels like I'm going to get t-boned at an intersection. Acceleration from a stop was so bad I would avoid unprotected left turns at all cost.

I'm glad that the performance has improved slightly but i need this to be much more responsive. Bank 1 is still reading at 107% long term after being driven without the vacuum leak. I'm planning to double check for leaks just to be sure. Tried fiddling with the idle valve but timing is still being held to 5 degrees which appears to be the minimum allowed.

@ 3QJay
Yes, after tinkering with it for a while longer I believe you are correct. 10% duty cycle on the iaac seems to be as low as it will read. Great insight. Same with the timing being at 5°.

And about the oxygen sensors and rapid switching that's exactly what I meant

The little flying saucer thing? That is the BPT (back pressure transducer) yes, part of the EGR system. Is it just the hose cap leaking (can't quite tell what the arrow is pointing at).

So. You have slow cycling on bank 1 O2 when steady part throttle cruise?

3Q Jay wrote: ↑

Mon Oct 03, 2022 6:49 pm

The little flying saucer thing? That is the BPT (back pressure transducer) yes, part of the EGR system. Is it just the hose cap leaking (can't quite tell what the arrow is pointing at).

So. You have slow cycling on bank 1 O2 when steady part throttle cruise?

Yes thats the one. The arrow is pointing at the whisp of smoke.

Bank 1 cycles fine at part throttle but holds lean at idle. Bank 2 is close to optimal. A little rich maybe but it was minimal.

That BPT valve is still available new from Nissan if yours is bad - I just replaced it on mine last year. It’s used on some later model Nissans as well which is why it’s not yet discontinued.

I know these questions may sound dumb, but have you double checked the engine harness connectors 1-6 and engine grounding points to make sure they aren't loose or swapped? Also, double checking your timing marks and CAS positioning in reference to BTDC, since you did swap out transmissions. Lastly, have you tried the on-board diagnostic tests, namely test 2 and O2 sensor check off the ECU? You should be getting code 55 and then allowed to check O2 sensors. Going through every step of the diagnostic procedures in section EC starting from the beginning would be my next move, especially because of all the previous work done too the car. Additionally, your door/seat electrical issues might be due to previous work done in fixing your window regulators. Not doubting your skills, but in my experience, most of the electrical gremlins I see with 1st gen Q45 are usually self-induced.

For example, I just had a right rear Bose amplifier go bad. When I took off the cover, I found the amplifier wasn't even screwed into the cover. It was just hanging loose, which caused it to probably overheat. I replaced it with a spare front amplifier- not ideal but better than nothing.