VQ35 timing

mal · Post by **mal** » Tue Jan 16, 2018 7:37 pm

Hello,

I am new to this forum, but have been working on installing MS3 on a VQ35 (Maxima) engine.

With the CAM signal on bank 1, spark seems to be off by about 120 degrees.

I have double checked that the timing chain is installed properly, also confirmed that the flywheel is installed correctly.

Looking for any suggestions on what might be wrong? Anyone out there have experience on the VQ35 timing?

I included the logs I collected on the timing signals.

Thanks

billr · Post by **billr** » Wed Jan 17, 2018 11:14 am

Post the MSQ.

mal · Post by **mal** » Thu Jan 18, 2018 12:38 pm

Attached

mal · Post by **mal** » Mon Jan 22, 2018 12:25 pm

I am guessing VQ35 is not that popular?

Post by **jsmcortina** » Wed Feb 21, 2018 8:49 am

I checked through the history of the VQ35 decoder and I haven't found any firm records of customers actually using it yet.

In your log there are a number of frames of data with no-sync and then in frame 5 it syncs up. Is this what's happening all the time at the moment? i.e. cranks for ages before it shows RPM and syncs?
Given the lack of existing customers then it would indeed seem to be incomplete. Adjusting the phasing to address the 120deg issue is straightforward enough. Fixing the slow start up (if I'm seeing it correctly) will require some reworking of the sync-code itself.

James

mal · Post by **mal** » Fri Feb 23, 2018 12:13 pm

I see there is a way to adjust the offset (process using a timing light, etc), but the software seems to ignore very large numbers. I don't recall exactly where is stops making any change, maybe +/- 20deg?? Anything more than that is ignored.

Your response is very much appreciated, but being a noob- I am not sure what action to take on it.

Post by **jsmcortina** » Fri Feb 23, 2018 12:26 pm

My post was slightly ambiguous, when I said.

jsmcortina wrote:Adjusting the phasing to address the 120deg issue is straightforward enough.

I was meaning inside the firmware at source code level. It isn't easy to adjust as an end user.

How about the sync issues though? That seems to suggest that the decoder needs more work before it is production ready. Do you have a regular datalog of a starting attempt?

James

mal · Post by **mal** » Fri Feb 23, 2018 3:29 pm

I think the file I uploaded was an attempt at starting the engine. While I was cranking, we had the timing light on and observed it was firing 120deg BTDC.

If there is some other data I can collect, please let me know what needs to be done. I will be in the shop tomorrow, and can collect more data.

mal · Post by **mal** » Fri Feb 23, 2018 4:01 pm

Some other logs I took back in December. I don't recall exactly why I took them (I think I was following the video posted on YouTube).. Hopefully they are helpful.

Post by **jsmcortina** » Fri Feb 23, 2018 4:12 pm

How about a datalog?

Datalogging -> Start

James

mal · Post by **mal** » Sat Feb 24, 2018 6:33 pm

Attached..

2 tries, 1st one would not sync.. then I tired again, and got sync.

Post by **jsmcortina** » Mon Feb 26, 2018 5:17 pm

That non-sync says that something is wrong.

I'm hoping to hear some more from the other customer here: http://www.msextra.com/forums/viewtopic ... 31&t=68396 so we can understand if it (the non-sync) is a decoder problem or something specific to your install.

James

mega_user · Post by **mega_user** » Mon Feb 26, 2018 5:55 pm

Since the trigger wheel is on the flywheel itself it is possible to turn the flywheel 180 degree around and have the trigger points wrong.
Do not mix Maxima and 350Z fylwheels as the mounting points for the crank sensor are on different locations and the trigger point will be wrong again.
Finally the crank sensor is known to go bad with age. After checking for the correct flywheel , correct flywheel orientation also try a new sensor.

supakat · Post by **supakat** » Mon Feb 26, 2018 6:15 pm

JSM asked me to chime in. I have a swapped a 2004 VQ35 from a 350z into my S13 240sx. I used all stock sensors as well as aftermarket flywheel. The wiring was straight forward for me.

Crank Sensor ---> Crank Input Pin24 Main MS3 Harness
Passenger Side Cam Sensor ---> Cam Input Pin 32 MS3X Harness
Driver Side Cam Sensor ---> PT4 Datalog Input Pin 30 MS3X Harness

Drive Side Cam does not need to be wired in to start. It is used to enable VVL. I have not enabled this feature as of yet.

Attached is the MSQ. One major thing to note, I cannot get sync with Falling Edge. My capture is set to Rising Edge. Also, I did not need to adjust the offset angle. It is right on the money at 0*. I was amazed when I timed the engine that this was the case. I also had an issue with the wiring at first. I thought the Cam and Crank sensors were wired the same. The polarity is switched between the two. If you look at the FSM, it will show you the proper pins although the middle pin will always be the signal. I did this by mistake when I pulled the wiring from the donor car. The Cam and Crank plugs can interchange but the pinouts are different as stated above.

As for Maxima vs 350z VQ. I do not think Nissan would change the mounting points of the sensor on the bellhousing. Mine is right next to the slave cylinder. A quick search shows that it is in the same place. As for flywheel markings, this could be a possibility that they are different. Hope this helps.

mega_user · Post by **mega_user** » Tue Feb 27, 2018 7:29 am

Did you use 12V or 5V to power the hall sensors?

Do the hall sensors need a pullup resistor?

supakat · Post by **supakat** » Tue Feb 27, 2018 9:34 am

Great point I forgot to mention that. Early VQ are 12v. Later years are 5v. My 2004 is 12v and my 2013 Murano is 5v. Knew I was missing something. Check the FSM for your specific application.

http://www.nicoclub.com/nissan-service-manuals

No resistors used. Wired up as the MS3 docs say.

mal · Post by **mal** » Wed Feb 28, 2018 4:11 pm

Forums are not sending me emails when there are updates... Sorry for the delay in my response.

The crank position sensor is on the upper oil pan. I am told by Nissan people that the FWD and RWD position of the sensor is different on these engines, and the trigger points on the flywheel are adjusted to compensate so (on the early VQ35 engines) the patterns expected by the ECU should be the same for both versions of the engine.

My setup uses a custom flywheel. Initially, it was incorrectly set up for the RWD position even though I am using a FWD engine. In this configuration, the engine actually ran (poorly). Ignition fired a bit too early even with adjusting the offset. After weeks of trying to figure out what was wrong, I realized the trigger points on the flywheel were wrong. I dropped the transmission and fixed that. I confirmed the position is now correct side-by-side with a stock FWD Nissan flexplate. After I assembled everything, I confirmed the pattern is the same by peeking through the crank position sensor hole. At this point, I am fairly confident that the mechanical is correct.

Based on the fact that it ran poorly at one point, it left me thinking that my electrical hookups are correct. I did not realize there was a 5V vs 12V issue, and I will look in to that further. IIRC, my engine is out of a 2004 Altima. I wired the sensors as per the MS3 manual. There were waveforms on the logs that I uploaded to the forum, so again- I suspect the electrical hookup is correct.

I am using the cam sensor on the side of the engine with cylinder #1. It is hooked to the CAM+ input on the MS3. I don't recall which input I hooked for the other cam sensor, but I did hook it up in hopes of getting the variable timing working. (Supakat- did you have issue with this that it is not enabled yet?)

My configuration is using most of the "default" settings with VQ35 timing selected. I will check this weekend if I am on rising or falling edge. I will also check my wiring on the sensor plugs, but again- odd that I would see any signal if that was wrong.

Thanks for all the responses!

Post by **jsmcortina** » Wed Feb 28, 2018 5:21 pm

mal wrote:I included the logs I collected on the timing signals.

The phasing of your cam signal looks incorrect, to start with it is maybe 15 degrees early (that's why it won't sync), but then later it is maybe 20 crank degrees late??
So something odd with the cam input signal.

James

supakat · Post by **supakat** » Wed Feb 28, 2018 7:22 pm

No issue with it enabled. I want to get a good base tune before I start to play with VVT. You most likely are 12v for that year. In later years, they switched. My CAM In is on the Cylinder one cam as well.

I hope the capture is your issue. Rising Edge gets me going.

mal · Post by **mal** » Fri Mar 02, 2018 6:32 pm

jsmcortina wrote:
mal wrote:I included the logs I collected on the timing signals.
The phasing of your cam signal looks incorrect, to start with it is maybe 15 degrees early (that's why it won't sync), but then later it is maybe 20 crank degrees late??
So something odd with the cam input signal.

James

Could that be due to the sensor being wired wrong? or having the wrong voltage?

I don't see how the cam can be physically wrong. I did double check that the timing chain was installed correctly. I am also using high-lift cams from JWT that would cause the valves to hit the pistons if the timing was off enough. So, I am pretty sure it is mechanically correct.

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