MAP noise

[Mark h]

This is an MS3.57 extra running firmware 1.3. Its a Ford 2.3 turbo I'm trying to run sequentially. I have been trying to figure out my unsmooth MAP for a while now with no success and was hoping for some insight into the issue. At one point the MAP was smooth and I'm not really sure when it became so bumpy. The car seems to run fine it just seems my boost control could be better if my MAP was smoother. At one point it was worse than it is right now but I replaced my ignition wires and that helped a bit. I think its some kind of electrical noise because my "Sensor 02" is a pre-intercooler MAT and that also seems to jump up and down very unsmoothly although its not totally obvious in this log. I've tried no belt on the alternator. I've tried unplugging my boost controller, water injection, O2 sensor, Bluetooth, pretty much anything that I don't need to make the car run and it doesn't seem to make the issue go away. I've cleaned all the grounds. I've moved grounds for both the MS, the block, and the battery in every fashion I could think of. Currently the battery is connected to the block. The MS is also grounded to the block at a different point. I've messed with the MAP line to the MS and it hasn't seemed to change anything.

Some other possibly related issues (but probably not) include:
1. I am having cam sync issues. Sometimes, even if I have a clear cam signal in my composite log, I get a cam fault code. Sometimes it syncs.
2. While running Shadow dash I get some funny things happening with the SD card reader. It will blink on and off/ready not ready with no SD card in the MS. Doesn't seem to affect anything though so I haven't tried to figure that out yet.

Any input would be appreciated. Thanks in advance.

[Matt Cramer]

The MAP signal in that log looks fairly smooth to me. Was that the wrong log by any chance?

[Mark h]

Nope right one. It used to be smooth and now its really....steppy. Like when MAP is rising its in steps. It seems like it doesn't always do it. Sometimes it does it worse than others. In one of the examples a bunch of other stuff went funny like RPM and Sensor 2. At some points I believe it is affecting my boost control negatively. The two examples are pre new ignition wires but I still think something is funny. Maybe not.

[elaw]

Are you talking about jumps like at 708359.94 seconds in the second file you attached?

To me, that looks like a logging problem and not a problem with the raw data. If you step through the log and look at the timestamps, it's doing some weird things... some timestamps appear to be repeated (even though the associated data values change), and the amount of time between one and the next seems highly variable.

I wonder if this could actually be a communications problem between your computer and the Megasquirt?

[Mark h]

I had not noticed that. Thanks for pointing that out. Could that have anything to do with the issue I was having with shadow dash and it flikering the SD ready thing at me?

What do I do from here? I can get a log from MS on an SD card instead and see what that looks like. Would that tell us anything? Could noise from the car be causing the issue?

[elaw]

Did those logs come from ShadowDash? If so, presumably over a bluetooth connection? Bluetooth can be tricky, and electrical interference can definitely affect bt connections. And electrical interference can also affect the Megasquirt itself.

Also I think there was an update to ShadowDash recently (I use it, but not very often)? Do you think the start of this problem might correlate with the update?

Looking at an SD log quite possibly could provide some insight too. If the SD log doesn't show the same weirdness as the regular log, then a problem with the MS itself can probably be ruled out.

[Mark h]

All of the logs I've posted have come from data logging on my PC. I have yet to try and log with Shadow dash. I'm not sure I have the update but I don't think that is the issue. I did notice that if the bluetooth was plugged into the MS when you were also connected to the computer it would do some funny stuff so I disconnect the bluetooth whenever I have it plugged into the computer. It may take me a few days to get an SD log.

Thanks for the help so far!

[elaw]

No problem!

When logging with the computer, are you using a USB or RS-232 (serial) cable?

USB connections are notorious for having noise issues. If you don't have a serial port on your computer you can use a USB-to-serial dongle, but the recommended setup is to keep the USB part of the connection as short as possible (8" or less preferably) and if more length is required, use a serial cable between the dongle and the MS.

[Mark h]

As an update. I've switched to an rs-232 cable with a usb adaptor at the computer and the issue no longer seems to be present. Thanks for helping me figure this out.