MSefi.com read only forum (Jan.15,2018)

I'm having repeatable map oscillation at specific pressures ( 40-55 kPa ) when under light load cruise. I tried disabling EGO alltogether but autotune had no clue what the AFR was and just leaned the crap outta everything. heh If I instead set the controller auth to 0%, will autotune still update my tables while driving?

Side note - I'm using a rubber vacuum hose from the throttle body to the MS-II. Could the oscillation be due to the length of that hose and the rubber deforming and sending pressure ripples down the length? Should I get a stiff rubber hose instead?

I'm assuming you have a Wideband?
If EGO Controller Authority is set to 0, TS will still tune, but it is entirely left to the WB's AFR.

You can do it with narrowband too, but with narrowband I highly recommend leaving ego correction on.

I find oscillation troubles are often spark timing related.

Can you post an msq and data log?

LT401Vette wrote:I'm assuming you have a Wideband?
If EGO Controller Authority is set to 0, TS will still tune, but it is entirely left to the WB's AFR.

You can do it with narrowband too, but with narrowband I highly recommend leaving ego correction on.

I find oscillation troubles are often spark timing related.

Can you post an msq and data log?

TY!

Yes, Innovate LC-1 wideband.

I think my MSQ is out of sync with the log, but will post it. Need to transfer from laptop.

LT401Vette wrote:Can you post an msq and data log?

Here's the log & MSQ. Good example at 2297s.
TY again!

Note - some of the spark table in that MSQ is out of date ( values 36.0 are 32.0 ) but shouldn't be related to this issue.

Interesting. Trip home with EGO auth off resulted in no AFR oscillation even though the mapdot was still wonky. Will log my trip to work in the morning to make sure it wasn't a fluke.

In that log it does look like your ego correction is sort of chasing its tail.

Perhaps slowing down the EGO Correction reaction time so the AFR gets more time to provide feedback for the step.
I would start out trying to double it up to 32 ignition events per step.

LT401Vette wrote:In that log it does look like your ego correction is sort of chasing its tail.

Perhaps slowing down the EGO Correction reaction time so the AFR gets more time to provide feedback for the step.
I would start out trying to double it up to 32 ignition events per step.

Awesome - will give that a shot on the way home.

Does the noise level in my map / clt / voltage seem normal or is there a way to completely clean those up. Is there a log I can look at somewhere to see what the noise levels SHOULD be? haha

Thanks again!

The sensor readings don't have a terrible level of noise, but there seems to be occasional voltage spikes that are causing significant changes to the PW calculation.

LT401Vette wrote:The sensor readings don't have a terrible level of noise, but there seems to be occasional voltage spikes that are causing significant changes to the PW calculation.

I ran across a post ( http://msefi.com/viewtopic.php?f=38&t=40183 ) to help with voltage spikes. Would this help? Or is there a voltage spike thread you have handy for troubleshooting? I wired mine up years ago ( 2005 ) and there were many threads with voltage spike issues back then, but no solid DO THIS TO FIX ALL results at the time. I assume someone found the perfect fix and likely updated the wiring documents. I need to pull mine apart and compare to the current diagrams it seems.

The main grounds from pins #8, 9, 10, 11,& 18 go to one spot on the engine block. Do not ground them at physically separated locations, and do not use a single fat wire for this. Instead run separate wires from the pins all the way to the ground spot.


Hmmm. Definitely don't have this. All of those pins are jumpered together on the DB37 and 1 wire goes to the engine block and connects in the same place as the sensor grounds. Should I have 5 separate wires grounded to a separate location on the block than the sensor ground ( and the sensors ground wired should go to DB pin 19 and not to the block )?

Thanks!

Edit - sorry, I got way off topic. The other forums are a ghost town. O.o

The sensor grounds should be grounded at the MS DB37 - not the engine block. The idea being that you have heavy current flow in the MS ground due to injector load while the sensors work at very low current. If you share the grounds that high current can interfere with the sensor operation.

trakkies wrote:The sensor grounds should be grounded at the MS DB37 - not the engine block. The idea being that you have heavy current flow in the MS ground due to injector load while the sensors work at very low current. If you share the grounds that high current can interfere with the sensor operation.

Awesome - TY!

So, if my coolant sensors are single wire, I'm doomed to the named interference.

fordfanboi wrote:

trakkies wrote:The sensor grounds should be grounded at the MS DB37 - not the engine block. The idea being that you have heavy current flow in the MS ground due to injector load while the sensors work at very low current. If you share the grounds that high current can interfere with the sensor operation.

Awesome - TY!

So, if my coolant sensors are single wire, I'm doomed to the named interference.

I've not seen single wire (block return) types used on an injection system. They are more common for the car temp gauge, etc. Is there not a two wire one that will physically fit? MS should be able to adapt for different electrical characteristics.

trakkies wrote:I've not seen single wire (block return) types used on an injection system. They are more common for the car temp gauge, etc. Is there not a two wire one that will physically fit? MS should be able to adapt for different electrical characteristics.

True, I have two installed and I could easily purchase one with two wires for the MS-II and leave the single one going to the digital gauge. I believe the recommended GM two wire sensor is the same thread as my single spade. WIll swing by Autozone and see what I can find.

As a followup to the original post, now that my TPS ground is pointing to pin 19 instead of the engine block and my Authority is 10% ( was 15 ) / Steps 32 ( was 16 ), it's completely stable at cruise.

TY for the help guys!

Great!