So late last year I was helping a buddy with an issue with his VVT on his track car. In part of the diagnosis, I swapped the actuator from my car to his. As soon as I did this, I had no VVT actuation in my car. We swapped the actuators back and I still had no VVT actuation with a VVT1 error.

I am at my wits end with this issue.

Here is a list of the things I’ve tried to resolve the issue:
Oil change, due for another one
New O-ring kit
New solenoid
New to me cam phaser
Sent the ECU back to DIY Autotune for testing
Ran new wires from the ECU to the solenoid
Tested both solenoids
Ran test mode in Tunerstudio
Put an oil pressure sensor on the oil feed for the VVT
Blew out the cam and all VVT pieces

The current status, when I start the car, I get VVT actuation. Go for a short drive and the VVT stops moving and shows 0.2-0.5 degrees, no matter what the angle the ECU is calling for.

I am wondering if I didn’t nick an O-ring during all the off and on with the solenoid assembly, etc.

When I get back to my PC, I will upload the msq and some logs.

 

I changed the oil and actuator again still no change. I am getting VVT action after start-up, but after a bit, it stops working and goes to zero. I am attaching my current msq and some datalogs. Please help me!
2022-07-10_12.27.47.msl
2022-07-10_12.28.54.msq
2022-07-07_19.57.36.msl
2022-07-10_12.26.57.msl

 

What is the DC when you aren't getting VVT advance?
use the procedure in the MS3PRO manual to determine the absolute cam angles. The MS3 will do strange things if the absolute angle is outside of the relative range you put in the VVT settings window (FW dependent)
After getting the actual absolute angles, use a min angle that yields true advance (5 degrees) as opposed to the 0 degrees base advance typically shown around these parts, adjust target table appropriately (advance table 5 degrees)

Edit: turn off range check and tooth filter if they are turned on, use SD logging at 5msec if possible

 

According my logs, the DC was around 52% with my target VVT angle of 11.5 and actual of 11.2 degrees. The actual angle tanked down to zero and the DC went up to 80%, which is my max. It is hard to tell, but it looks like the MS is trying to get the VVT cam to meet the target as it starts falling and it is increasing the DC.

I am now wondering if I am getting some kind of oiling issue, like a failed o-ring. Even though I have replaced them once already, I may try to replace them again.

 

Yeah, that sounds like it is mechanical. The apex seals and springs in the phasor can be misaligned and cause issues like this as well.

You also need oil pressure to the phasor to release the locking pin.

 

I replaced a two of the O-rings and I am still getting the same issue. If I shut the car off and wait a few minutes and restart the engine, VVT starts working again for between 30 seconds to a few minutes and then stops again.

 

Thanks for your help so far. This is the second cam phaser with the same issue.

I have an oil pressure sensor mounted in the oil feed line to the VVT at the back of the head and I am getting decent pressure. Do you think there may be some crap lodged in the cam, blocking oil flow to the phaser?

I am going to try and replace the VVT housing that houses the actuator and the tube with the o-rings mounted to the head under the assembly.

 

Possible, there is also a basket style filter right where the hard line attaches to the actuator housing. Pretty easy to check/clean that.

 

That filter was replaced when the o-rings were replaced.

 

What’s your oil pressure? It won’t operate below a certain value. I’m not in front of my computer now, but there are pressure values for idle and 3500rpm on the VVT engine. I’ve had that issue before with a poorly clearanced engine and not a big enough oil pump for VVT.

 

In one of my datalogs, I was seeing 34/38psi as I was trying to hold the engine at 1600-1700 RPMS when the VVT actual angle dropped to zero and the DC went to 80%.

 

I typically see 18/22psi at hot idle and mid-50's when revving it. My oil pressure sensor is tapped into the back of the VVT oil feed banjo bolt.

 

I ran a test last night, I started the car and waited for the VVT to stop working. Once it stopped, I unplugged the solenoid and attached a 9volt batter to the solenoid and the VVT cam moved. This would lead me to believe that my issue is with the megasquirt itself. Can someone please confirm that you can use an injector driver to operate the VVT? I have already tried using High Current Output 1 and 2, I get a conflict on 3. I may go back and retry Output 2, as I tried it a while ago.

 

To be clear, you have used 2 different outputs, and had the ECU checked by DIY?

If this is the case, check the wiring.

 

I tried both High Current Output 1 and 2 using my current wiring. I ran new test wires from the expansion plug for both 12 volts and Output 1 to the solenoid and the VVT still dropped out in about a minute, I did not try output 2 as it started pouring and I was working outside. Shortly after my VVT stopped working I was running a VVT valve test in tunerstudio to see if the solenoid was working. I performed the test and the cam moved when the test was enabled, and it seemed like the car back-fired and the engine shut off. The car would not restart. Doing a data log I noticed I was no longer getting any map sensor data. The ECU was sent to DIY who said the map sensor lifted off the board and they resoldered. I also had them test both high current outputs, which seemed to pass their tests.

Another data point, when the VVT drops out, I get constant voltage between 12 volts and the high current output wires at the solenoid. I would expect this voltage to vary. I will be picking up a set of noid lights to see if I can see a flashing signal, like an injector output pulsing to ground.

 

I picked up a noid light last night and hooked it up. With very low duty cycle, I got a dim light on the noid light. As I increased the duty cycle, the light got brighter and brighter.

Can someone with functional VVT let me know if the solenoid clicks or hums when running the VVT Test mode or does their solenoid only click once when enable and disabled? My solenoid will only click once when I enable the VVT Test and then click again when I disable the test. Thanks in advance.

 

Are you clicking on/off or pulsed? You should be pulsing it.

 

I was using the VVT Test mode in the VVT Settings tab, which is only on or off. I will try the Output Test Mode and see what I get. Thanks again for your help.

 

I looked more into this. Is this the 12-27-47 log? I see VVT angle go to zero and DC increase to max, but I also see target go to 0.

Can you take a log of it just idling until the VVT stops working?

 

Will do.