Megasquirt Support Forum (MSEXTRA) ? VVT Issues (View topic)

 

The MSLabs MS3 basic has very little in common with the MS3X v3.57
For a start I know it uses the MAX9926 for the VR sensor input. Not sure what is used on the cam sensor input: best to ask Reverent.
Could very well be an issue with your CAM sensor itself: is it a lot of trouble to try another cam sensor?

 

Missed the part where this was an ms3 basic. Nevermind. Not the same issue as me.

 

Well, I'm not really upset that ECU surgery is off the table. I perused through some old pics of my ECU and the whatever is labeled C13 definitely is not a standard round capacitor.

Swapping the sensors would not be a big deal, but the cheapest one on rockauto is $25 and I don't think it will fix the issue. If I don't go below 3,000 RPM there is no problem, so I have a hard time believing the sensor itself is wonky at low speeds.

I added a ferrite core to the coil power wire and gave it three wraps, and the issue hasn't gone away. I'm going to try adding some capacitors to the ignition power and signal wires next, maybe some aluminum foil shielding on the cam sensor wires. EDIS capacitor will do fine for the power wire, but I'm going to have to do some learning for what kind of capacitors I'd want to wire into my coil signal wires to replicate what MSExtra shows. I don't really want a standard solid wire breadboard type capacitor in a wiring harness.

 

Your VVT angle never seems to go below ~15 degrees, even at idle. Check that your VVT start angle is correct.

 

That is something I had noticed, but I wasn't sure what to make of it... I changed the belt on this thing two years ago and we had to take apart the VVT actuator/pulley to change the cam seal due to a stripped Torx head. Hope we didn't bungle something up, but it may be best at this point to take it back apart and see what I find in there. It ran strong for 12,000 miles on the stock ECU with no CELs or anything.

Min and max angles seem appropriate based on other peoples base settings. I haven't fiddled with VVT settings up to now. Guess I'm going to turn that "Tooth Filter" setting on and see what happens.





New datalog, new screenshot.

 

The min and max angles are not cast in stone, you need to adjust them for YOUR engine.

 

Understood. Every thread I've seen shows that somewhere in the 270's is normal. Offsetting to about 290 seemed far out, so I haven't changed that value... Still thinking I'll wind up pulling the valvecover and timing cover to check timing marks are correct.

 

I know it's been a while but did you ever figure this out? I have the same issue.

 

~15 degrees of offset in the intake cam timing is almost certainly a mistimed intake cam.

 

Thanks. I do agree it sounds like it. However it basically has 15 degrees of advance built in. Whereas if you have a tooth skipped generally, doesn't that retard the timing?

Is it possible the belt was not put on at TDC or something? This was a 70k mileage junkyard engine from Europe. I've had a car with a tooth off and it didn't drive well. This one drives totally fine. We got 130whp out of it and 118 tq and the car feels and sounds good so it's weird.

Could be a cam position sensor that's dying or giving weird readings?

 

An in intake cam can be mistimed in either direction. FWIW, a non VVT B6/BP has 17 degrees of advance from the factory IIRC. VVT is variable from 5 to around 50.

It ~could~ be any number of things, the only way to know for sure is to actually get on the HW.

 

Thank you. What is the "HW"

 

hardware