Bogging Under load, Upstream sensor code

Got the data logging to work and made a comparison of the various load PIDs on offer, plus the Torque built-in Volumetric Efficiency. Don't ask me how it does its VE calculation, 'cause I have no idea. Just wanted to see how they all stack up:

Awesome! To revive this thread, i’m trying to figure out why my [IADV] Camshaft Adv Angle B2 is showing a constant value of -128, where the B1 side is showing changing values. You should be able to see this in the excel file i uploaded originally. I think this may have something to do with the random dip and return of RPM after letting off throttle. I tried swapping both Cam position sensors from B1-> B2, but the problem didn’t swap banks. Any other sensor I should be looking for?

coolbro50.d wrote:

Awesome! To revive this thread, i’m trying to figure out why my [IADV] Camshaft Adv Angle B2 is showing a constant value of -128, where the B1 side is showing changing values. You should be able to see this in the excel file i uploaded originally. I think this may have something to do with the random dip and return of RPM after letting off throttle. I tried swapping both Cam position sensors from B1-> B2, but the problem didn’t swap banks. Any other sensor I should be looking for?

I noticed that! I think the bank two PID just doesn't work.

You can tell by the Cam Valve Duty (%) PIDs. They're pretty equal throughout the capture. I graphed the two for giggles:



Some differences here and there, but pretty much the same. So, if the ECM is getting the camshaft timing changes it wants from bank one using the solenoid this way, and the bank two solenoid is run in a similar way, then it's logical that the ECM is also happy with the bank two camshaft timing. Despite what that PID is saying.

If bank two truly wasn't moving, then one of two things would happen. One, there's a base timing problem, which would result in a cam/crank correlation problem, and the ECM wouldn't use the bank two solenoid at all. Two, the base timing is OK, but the ECM can't get the cam to advance. That'd result in the ECM turning up the solenoid duty cycle until it got a reaction, or it set a code. I've seen the ECM turn these solenoids up to 70 or 80% and stay there in an attempt to get the cam to move the way it wants. Yours isn't doing that.

In other words, I think your cam timing is fine. :silly:

It’s good to hear you think the timing is okay. For the dip in rpm’s i’m experiencing, do you have any insight? It happens when at speeds under around 40 when letting off the gas. when i let off, the rpm’s drop very low pretty quickly and then immidiately bouce to where they should idle. It results in this jerking motion of the car. I smoke tested the intakes, and there’s no obvious leaks. Also tried 2 new mafs, and have freshly cleaned TBS.

coolbro50.d wrote:

It’s good to hear you think the timing is okay. For the dip in rpm’s i’m experiencing, do you have any insight? It happens when at speeds under around 40 when letting off the gas. when i let off, the rpm’s drop very low pretty quickly and then immidiately bouce to where they should idle. It results in this jerking motion of the car. I smoke tested the intakes, and there’s no obvious leaks. Also tried 2 new mafs, and have freshly cleaned TBS.

Was the dip in engine speed caught on any of the previous captures? Could you point out a particular frame of data if it was?

Just shooting from the hip, it sounds like an ECM idle adaptation issue. Have you run an Idle Air Volume Learn since cleaning the MAF's and the throttle bodies? If not, I'd start there.

It probably was caught in previous captures, but i’ll take a new log just to get some good examples of it. I have run the Idle Air Relearn as well as throttle position relearn but nothing has changed. However, I did read this on a thread: “FYI: If you have an 2007 G35/350z (with VQ35HR) motor, there is a bug in the ECU software and the idle air volume won't run to completion, resulting in a high idle and surging as the ECU tries to correct it.” Unsure the truth behind it though. Found it here: www.myg37.com/forums/engine-drivetrain-a...olume-learn-fix.html

Hey, I took two new logs today. Ever since swapping the downstream o2s for OEM ones, Fuel trims have looked much better. I have a bit of an exhaust leak from my test pipes where they mate from the manifold, so I think that explains the small amount of high fuel trims that I see strictly when im idling. When moving, the fuel trims look good, and my long terms are right around 10, so im not running crazy lean either. Anyways, the first log just shows the car after startup hunting for idle, but it never finds it. It does this almost every time its started up and not still close to operating temp. The rpms go up, come down, kind of with a mind of their own, all within a few hundred RPM. The second log (you can tell the first log from the second log because the headers will appear again) shows a drive where I was intentionally trying to get the RPM dip to occur. To describe the dip, It usually happens when im cruising in a higher gear, so lower rpm, and a low ish speed. If I remove my foot completely from the gas, instead of the RPMs slowly returning down to idle speed, they fall quickly down below idle speed, and then just as quickly as they fell, they jump back up. It makes the car lurch forwards, and makes coming to a stop very uncomfortable. I think if you look at throttle position up against RPM, you will see me remove my foot from the throttle, and the the rpms dip down and then jump back up. Ive been chasing this for a while and haven't been able to find any correlations. I included a lot of PIDS in the excel file because Im not exactly sure what the issue is, so feel free to delete any columns you don't find necessary or alter the file in any way you need. I have another copy.

Link to file:
docs.google.com/spreadsheets/d/1na_VCqaG...5&rtpof=true&sd=true

I want to also add that I have tried cleaning TB's, swapping MAFs with different ones, ECU resets, battery disconnects, idle air recalibration, and throttle position learning.