Sync Loss at idle or cruise VQ35

[supakat]

Setup is a VQ35 on MS3/3.57 using stock cam/crank sensors with MS3 VQ35 decoder. I tend to get sync loss when at a steady RPM at idle or when cruising. WOT or rising rpm does not show. I read this article and going to try turning R56. I will update with a composite logger as well. Just trying to get some insight so I understand better.
https://www.diyautotune.com/support/tec ... squirt-vr/

[jsmcortina]

Looks like a false tooth is coming in.
Please see if you can capture the problem using the "Composite logger"
Also attach a tune (MSQ) and regular datalog (MSL).

Can you confirm how this is setup? Another customer is reporting that the timing is wildly incorrect on his VQ35 install http://www.msextra.com/forums/viewtopic ... 31&t=68134 - any comments?

James

[supakat]

Sorry jsmcortina, I resolved the issue by adjusting the R56 trim pot till the issue went away at idle. Test drove and adjusted till it vanished by turning R56 clockwise. Not sure how many turns but close to 3 I would say. I did touch R52 at first but put back where it was. Idles smooth and accelerates clean. MS and their support always puts a smile on my face...

I have not fully tuned the car but the MSQ is attached. I still need to tune accel/decel and others but the main ignition settings are there for others to see. The crank sensor is wired to crank, the passenger cam sensor is wired to CAM IN, and Driver side CAM sensor is going to PT4 for VVL. I have not tuned/enabled VVL as of yet. Hope this helps.

[jsmcortina]

Any chance you could take and post a "Composite Log" of the engine at idle? It would be most helpful to understand what is different on mal's install.

James

[supakat]

I may have spoke to soon. I have a slight miss still. Hopefully you can help guide me how to interpret the Composite logger to adjust the VR conditioner correctly. Composite attached.

https://youtu.be/XWnV2NlgQOs

[jsmcortina]

There are false triggers on both the crank and cam. In frame 47 of that composite log, the false crank tooth causes a sync loss.
In that same frame you can later see a false tooth on the cam.

James

[supakat]

I will adjust R56 again. I messed with R52 as well. Do you think I need to play with this trim?

[supakat]

Got her cleaned up. Just rotated R56 clockwise about 3/4.

[supakat]

Ok, I am getting aggravated with this issue. Today, I am getting sync loss again with the same settings that worked the other day. Is this something that has been encountered before? This is what happened the first time I got her cleaned up. Next day, the gremlin came back. I am stumped why. Any suggestions?

[supakat]

So I may have finally corrected the issue. I read this on the VR conditioner page but never really paid attention since in never stated Nissan. It described my issue exactly. Since it stated that only 1 of for possible scenarios will work, I had already rising edge and normal polarity working but with sync loss. I tried falling edge with normal before when starting the car and no go. So I went falling edge with cam polarity inverted and it hasn't skipped a beat. Hopefully this may help out mal.

Nippondenso signals losing sync at a narrow, low RPM range

This problem happens most often on Nippondenso ignitions and other ignitions where you have a 24 (or 12) tooth crank wheel and a 1 tooth cam wheel. It can happen to Toyota, Mazda, and Honda vehicles. The problem is that the ECU loses sync at a specific RPM range, often in the 1000 to 2500 RPM area. This may be accompanied by the timing jumping.

What is happening is that one active edge of the second trigger is very close to the crankshaft position signal, happening almost at the same time. As the signal can shift when the timing increases, the second trigger goes from happening before the primary trigger to happening after it, and the ECU gets confused about which one of the teeth on the crankshaft position sensor is the #1 tooth. This typically gives Lost Sync Reason 11 and 17 in data logs.

To solve this, you will need to find out exactly which edge you need to trigger on. First change Ignition Input Capture from Rising Edge to Falling Edge, or vice versa. If that does not work, experiment with changing the active edge of the second trigger. Usually, only one of the four possible combinations of Ignition Input Capture and Second Trigger Active Edge settings will rev out cleanly.

[supakat]

https://www.youtube.com/watch?v=Br3q4gbYt4E

[jsmcortina]

Glad to hear that it is working ok for you now.

Have you tried out the VVT yet? That may need more work as I don't recall reading any customer feedback about it.

James

[supakat]

It is actually turned on but my duty cycle is set at 50% which should not change the timing. I noticed it a bit laggy compared to before when I had it disabled. Once I get a good base tune, I will need to tune the duty cycle and see how she responds.

[mal]

My MS3Pro does not have the variable resistors to adjust.

I have tried all four combinations of rising/falling edge, as well as inverted or not. Either the engine will not start at all, or will start only some of the time depending on which settings I have. At no point do I get reliable starting.

Will collect composite logs this weekend for all four configurations.

Based on my observation, 3 things possibilities are happening during attempts to start:
1. Everything works properly, and the engine starts within 1 second, and runs well up to red-line.
2. MS3 says it has sync, but it is firing at the wrong time (when it does this, the engine momentarily stops spinning because the starter can't overcome the spark at the wrong time- RPM's drop, and voltage drops)
3. The MS3 will not sync at all (so, no power is sent to the coils or injectors), and it will just crank.

Watching Supakat's video has me very jealous.