At higher rpms, the intake cam needs to be retarded in order to maintain engine breathing. (intake valve is kept open longer to take advantage of inertia effects.)
The key is finding the optimal transition period from fully advanced to fully retarded. The most efficient way to do this would be on a load based dyno. Hold the engine rpm constant and vary the cam timing to get peak torque. Repeat at 200 rpm increments from 2-6.5K+.

Ignition timing - yes
Valve timing (vtc equipped engines only) - not explicitly

That would not be a very useful comparison as ignition timing is only indirectly related to cam angle. Intake cam angle affects intake airflow which determines injector pulse width. Ignition timing comes from maps based on injector pulse width and engine rpm.

Maybe some of the EU gurus can shed some light on this one.

Below is a test sub-injector map I made to quickly fully advance the cams at 2K and then allow them to fully retard after 4.4K. Note all the cells for rpms >=4.4K are zero.

http://img.photobucket.com/albums/v2...njectormap.jpg

Now check out the plot of the IPW and IDC data taken directly from the EU data log,

http://img.photobucket.com/albums/v2...srpm060619.jpg

You can ignore the IDC data. It is meaningless.

Everything was fine until 4842 rpm. At that point for some reason, the IPW jumped from 0 ms up to 11.5 ms and remained there until I hit the limiter at 6600.
The rev limiter comes pretty slowly when the cams are fully advanced.

Any ideas?

Looks like the EU bug applies to the Sub map also.

Why that happens, I don't know. I do know that the IDC is incorrect for the corresponding IPW when this happens.

Try resyncing the EU by importing then exporting the EM2.

I have tried that as well as reloading the f/w (1.14) and creating a new .em2 file.

Contact Greddy...this HAS to be a common problem and needs fixed.

Do you have the speed sensor tapped or intercepted?

As a last resort, create a new EM2 from scratch and manually enter in the values.

Alex did anyone complain about the duration conversion thing? Sorry for the OT.

I believe Dandy has....

Yes I have documented the DC->PW issue with Greddy.

Alex this issue could potentially also explain my post-rev cut richness problem as I mentioned to you before, ie perhaps the RLC map is calculating based on DC and converting my PW inputs incorrectly. I did have to lower the PW's after all to get the same A/F as before the cut. I have not had a chance to go do the math to see if it is indeed the case, but it has got me curious. Otherwise there is no good explanation for it yet.

..........................

Dave I am unsure why you're seeing that spike. Are you getting any instability in the RPM reading in that area?

Can you send me the em2 and log file as well please? I'd like to take a closer look if you don't mind...

Bump. For the search impaired.

6spd Hayes posted the following thread

http://forums.maxima.org/showthread.php?t=486193

in the 5th gen forum which provides some very useful data for this thread.

In the graph below I overlayed the cam angles I measured using an oscilloscope (black dataset) with the data he collected using the Cypher data collection tool. As expected, the agreement is very good.

http://img.photobucket.com/albums/v2...cipherdata.jpg

The Cypher is a much more efficient and accurate way of collecting this type of data. You can see the cam position in realtime instead of having to do a series of calculations from crank and cam waveforms just to come up with a single data point on the curve.

The other useful information I found in 6spd Hayes data set is the VTC solenoid duty cycles. Below I have the solenoid duty and cam angle as a function of time (for wot)

http://img.photobucket.com/albums/v2...lenoidduty.jpg

As you can see, at 40% DC, the cam angle is held constant. DC is increased to 50-55% to advance the cams and dropped into the 25-35% range to retard the cam angle.

Hopefully we can get some data for a Z/G in the near future.

I will probably pick up one of these Cypher tools in the near future. Just the time savings alone for obtaining the cam angles directly is worth the price of admission.

Well it is not looking very promising for trying to split control of the VTCs between the ecu and the EU based on rpm.

First I tried using one sub-injector channel to drive both vtc solenoids and the other channel in NVCS mode to energize a relay to switch between ecu and EU control. The relay part worked fine but neither VTC solenoid would work when wired in parallel. I did have the correct resistors wired in to bring the impedance up to match that of a typical injector.

When I disonnected one of the VTC solenoids, the one still connected started to function. However, the relatively low frequency that it is being driven at also makes it slow to respond.

Also, the ecu gets upset when you take control of the VTCs away. After about three WOT test runs, the ecu stopped controlling the VTCs. I checked the codes and there was one pending for VTCs but no MIL yet.

Sick thread , guys , very apreciated

Here is the result of my first attempt for VTC control using the EU. I have overlaid my cam angle data (black curve) over the stock A33B curves provided by
6spd Hayes.

http://img.photobucket.com/albums/v2...srpm060824.jpg

As you can see without feedback control, a constant pwm signal > 40% duty will drive the VTC phaser to its limit which is about 8 degrees greater than the programmed stock maximum.

I will change the NVCS map to only allow EU control between 2.6 and 4K. Because of the 20 ms pulse width limitation, the EU cannot control VTC operation below about 2K.

-EDIT-
I just realized that I can use the EU VTEC output to activate the relay and that will free up both sub-injector channels for VTC control. I will have to give that a shot this weekend

Dave reading through this I was going to suggest using the aux output but now when I get to the end I see it occurred to you. :thumbsup:

What DC did you program between 2k and 2800 or so when the limit is reached? Or is that just the time it takes the solenoid to fully move the phaser from 0% to 40% sub I/J DC...

I am using an IPW of 20ms from 1K up.

The phaser starts rotating at around 2.2K. 40% IDC doesn't occur until about 2.4K so I guess there is a frequency dependence there as well.

Oops sorry I didn't read your post carefully enough and missed where you said "a constant pwm signal". I was also thinking 40% PWM not IDC... doh.

Basically I just didn't go through it carefully enough... :o But now actually taking the time to read back through it and look at the math it all makes sense.

SOO... I've heard that the injector maps are additive on the EU (meaning you can use both concurrently to net more than 20ms duration) and I haven't tested this personally yet but I'm sure you see where I'm going with it now that you will have freed the other Sub I/J channel up... :nod:

If it proves to be beneficial to have an additional 8 degrees of cam advance at lower rpms, I may invest in a pwm solenoid valve controller.

There are several inexpensive units available that you can adjust the output duty cycle from 0-100% using a 0-5V analog input. Seems like a good use for the airflow output map.

This is very interesting information. I am building a GT-2 350Z race car. Right now I have a VQ 30 in the car and am running a Motec ecu. I have a VQ35 to put in at a later date and was discussing with the tuner about the variable cams in the VQ35 so this will be usefull to have somewhere to start from and tune from there.
Scott

Both VTC phasers are now functional with the re-wiring I mentioned a few posts back. The EU is now fully advancing the cams between 2.8 and 4K with the stock ecu in control everywhere else.
The cam advance vs rpm is shown below (black curve)

http://img.photobucket.com/albums/v2...srpm060826.jpg

The curve is quite "jagged" because the data logger that I am using doesn't record samples nearly as quickly as the Cypher unit that 6spd Hayes used for the blue and red stock data sets.

To try and quantify if the change in VTC operation had any effect, I logged some MAF vs rpm data at WOT.

I did three runs for each of:
i) stock VTC control
ii) partial EU control
iii) VTCs unplugged

The results are below. Within the general scatter of the data, there is no noticeable difference between the EU fully advanced cams and the stock ecu controlled ones.

As expected, the airflow for the vtc off runs, was significantly reduced throughout the rpm range up to about 5.5K at which point the curves converge.

http://img.photobucket.com/albums/v2...srpm060826.jpg

Realistically the only area that I can see power being increased through supplementary VTC control is down low 1.5 - 3K.

Thanks for all the analysis, it's good info for sure. Would still be interesting to see the maps for the G/Z ECU's.

Do you plan to try some testing with full advance down lower in the rpm range from 1.5-3k? It's probably not that consequential even for street driving and certainly for racing the rpms are always up high, but still, just for interest's sake...

I am going to repeat the testing with the 2K2 IM installed and then decide if I want to pursue separate VTC control any further.

Who knows, it may be useful if one was to go with a modified IM and aftermarket cams.

Finally found some WOT Z33 VTC data over on my350z.com.

These graphs were taken from:
http://my350z.com/forum/showthread.p...ghlight=cipher

http://img.photobucket.com/albums/v2..._intakecam.jpg
[http://img.photobucket.com/albums/v2...ore2Bafter.jpg

The Z33 ramps up a few degrees higher and holds it constant from about 2 - 4.5K and then ramps down similarly to the A33B.

I saw this graph over there too a few days ago and thought of this thread. I meant to post it over here but never got around to it.:( It doesn't have that "VIAS dip" that the A33B has. I wonder how it would affect your midrange power with it ramping down smoothly. Interesting stuff...:)

I extracted some of the Z33 data and added it to the stock A33B curves for easier comparison.

I guess i have a new curve to shoot for now.

http://img.photobucket.com/albums/v2...VTCZ33A33B.jpg

Dave I'm forgetting, do you have the Z IM on there?

I did when I was testing the EU VTC control about six weeks ago.

Currently I am doing some flow testing on the Z IM so the stocker is on there for now.

Guys greddy has a new piggy back system that can tune CVTC, not sure bout VTC. check out the link. Would like to no how it works.

Link: http://www.emanageforums.com/forums/...read.php?t=579

My Japanese is a little rusty but according to the Trust site, there is an application for the VQ35DE but the 300hp version (variable exhaust cams) is excluded.

http://www.trust-power.com/v_manage.html

I suspect the exclusion is because the exhaust cam timing is controlled using a magnetic phaser instead of a solenoid operated hydraulic one like the intake.

This suggests that it may be controlling the solenoid valves directly instead of intercepting and modifying the cam position signals like other piggyback cam timing controllers do.

If this is the case, it would need to feed the ecu a false feedback signal in order to avoid a cam positioning error which would put the vtc system into failsafe mode and trip the MIL.

Here are mine.

2nd gear WOT. Didn't take it past indicted RPM for obvious reasons.

I guess TS does modify them :chuckle:

http://i4.photobucket.com/albums/y124/nmexmax/VTC1.jpg

:snap: Looks like you have the 350Z cam timing curve. :eek:


You have the L-spec ECU right?

This is why I had planned on sending my ECU back to TS for OE Z33 software. I had always assumed the VTC maps were different because of the A33 dual stage IM vs. the Z33 single stage IM.

Full spec. I asked for the 'Z33 tune'. So they charged me full tune price. And my timing and AFR are fairly aggressive, and now this. FTW?

Did you ever go with the external controller? I think this might be the key to unlocking VTC power for us with 3.0 timing cover.

A side thought: could you splice the wires from 3.0 to 3.5 ecu for crank and cam signal (with some filter to make waveforms compatible) then run the VTC wires from 3.5ecu to control PWM solenoids? I know this probably had been thought of already...but I've never seen anything about it.

If you're using ther 3.0 cover then you do not have any chance of getting VTC or any of its related controls. Keep in mind eng92 is using full A33B trim.

What specifically makes it so i can't use the vtc? I still have the oil squiters on top.

Do you have the VTC solenoids?

I think you meant to say VTC phasers.

^ Exactly. Without the VTC sprockets it's a no-go.

Thanks eng92, that's what I meant.

So, unless you have these 2 items, it's a no go.

http://i4.photobucket.com/albums/y12...x/Image012.jpg

http://i4.photobucket.com/albums/y12...Image011-1.jpg

That sucks. Now I just want to convert my 3.0 set-up to full a33b. It would have been so much faster. Thanks for the info.