Hello all

After 3 months of sitting in my garage, I finally got around to replacing the broken head stud and removing the power steering on my car. I took it out tonight and the dreaded sync loss occurs when under full boost, usually shortly after a gear shift and returning to large throttle inputs. I managed to get it on a composite log, attached, though I'll admit I'm not sure what I'm looking for here. Any ideas? Motor (and associated sensors) has around 55k miles. I'm thinking cam or crank sensor, but I don't know which, and replacing both seems like overkill? Or it could be something totally different, since there's no issue when driving around normally...

 

At the point in question it looks like I'm getting a double reading in the cam sensor trace

Is that something a new cam sensor will typically fix, or is there something else funky going on with my wiring?

 

That is your crank sensor. Are you using any of the noise filter features? You need to describe your ecu HW.

edit: ms3 basic in sig, fyi sigs don't show in mobile

 

To be clear, the blue is the crank. The cam has a single tooth on one phase and 2 teeth on the other phase (green).

 

Adjust your trimpot.

 

My apologies it's an ms3 basic on Ms firmware 1.5.1 I believe. I've never opened it - is there noise filter tuning in tunerstudio that I can adjust? I'm not sure if mslabs keeps the trim pots in there.

 

Yeah, in the ignition settings pull-down. RTM on how to configure.

 

If the sync loss only happens when in boost, and not when the car runs for more than say, 30 mins (which would translate to a bad crank/cam sensor), you probably need to run a better spark plug, such as the NGK BKR8E-IX.

 

It only happens in boost, and only sometimes. Back in October I did about 3 hours of track driving with no issues. The car has sat since then, and on my test drive the other night it happened 3 or 4 times.
I'll check the spark plugs (it's been a while anyway), but I'm pretty sure those are the plugs I'm running.

 

How do you guys have your crank signal wiring routed? I'm running the OE VVT coil packs but my crank signal wiring goes straight through that valley between the cams as well. Perhaps it's a noise issue there? Seems weird that it it's more load dependent than RPM dependent, and it never happened before I installed the turbo.

In the meantime, I'm trying to calculate what the noise filter should be at various RPMs but I can't find the dimensions of the OEM 99-05 trigger wheel anywhere. I measured about 2mm on the tooth width but I don't know the diameter. Has anyone done that exercise? The settings in there now look like so:

 

Well, maybe coincidence, maybe not, but I enabled tach period rejection and doubled the noise filter curve after 2500RPM and I drove it around a bunch tonight with no issues. Maybe fixed? Fingers crossed.

 

Update: No sync issues since other than on cold days when it takes a while to start. Completed about ~4 hours of track driving this weekend with no hiccups.

 

My settings

The entire thread traces my journey. I have the older, longer box MS3.

Cliff notes: Use filtering, and Analog O2 input. Maybe my CAN module was / is damaged, but I guess I don’t care. If my LC 2 gives out (and mine seems to be one of the solid ones) I’ll move to an AEM, 1.5.X FW and direct CAN in. I’ll have to verify that woks with MS-Basic, or only with MS3-PRO.

 

I have the AEM UEGO with direct CAN input and it works fantastic. I've never had a CAN module.