Let's talk MEFI

[justgary]

9 hours ago, JJ08 said:

I'm thinking to change the MAP sensor.

The ECM reads Barometric pressure with the MAP sensor after the key is on but before the engine is turning.

The three Baro readings you have posted are 102.0, 99.4, and 98.3 kPa.  Barcelona is very close to sea level, so presuming you are also running your boat there, you should see roughly 101.3 kPa.  This value will change with weather and altitude.  If it was stormy during your latest try or you tried it at higher altitude (98.3 kPa = ~200M above sea level), your MAP sensor is probably OK.

Cleaning the connections is a good idea, though.  I would also use a can of spray carburetor cleaner to thoroughly clean the inside of the throttle body.  Open the throttle to make sure you can get the edges of the butterfly and the little side passages inside as well.

[JJ08]

I have the boat out the water, and all the tests are done in the same place.

Altitude maximum 50m. But in the last days, we have a weather change.

It is possible the reason for barometric change.

I cleaned the throttle body and also, I changed the TPS sensor.

Things done:

· Rebuilding the engine. (Plackets, piston rings, valves, petrol pump).

· TPS sensor.

· Checked the cables.

· Clean all parts.

Sure that the MAP sensor is not the solution, but I bought it and will arrive tomorrow. I will check it and I will inform about the results.

Thanks.

 

 

 

 

[GaryDoug]

23 hours ago, JJ08 said:

Hi,

Thanks for your answer.

I checked yesterday. But now the problem is not the same.

Last 3 - 4 times that I started the engine, I had the same problem, 1.000RPM (also I think that when  coolant temp is around 140ºF).

Yesterday the problem it's completely the other around.

I need to advance the throttle 1/4 more or less so the engine doesn't stopped and more or less 600RPM. After 5 min., when I  put the throttle in neutral position, the engine stopped.

I'm thinking to change the MAP sensor.

 

I don't think the MAP sensor is the problem since it correctly reads barometric pressure. It is curious why the target rpm is reported as 1000 but the actual rpm is far less and there is no unusual IAC position reported. But I do notice that the ignition voltage is very low.

[Steve B.]

On 4/27/2022 at 3:55 PM, justgary said:

I just wanted to tidy up the information in this thread so a person could know how to build a cable without chasing a bunch of posts.

Purchase list:

• TTL-232R-5V-WE - USB RS232/5V TTL Cable (do not get the 3.3 volt cable!)
• 12045808 - Delphi Connector Housing (MetriPack 150 series)
• 12124264 - Connector Lock (cover)
• 12045773 - Pins (You can figure out how to crimp them with pliers; buy spares)
• 15324973 - Cable Seal (Not required, but the wires fit better with them; one needed per pin)
• 1N4148 - Silicon Diode (any silicon diode should do)

The wiring diagram is simple:

Except that you also add the diode inline with the orange wire.  Put the cathode (with the stripe) toward the USB connector.

Also think about whether you want to add a switch to jumper pins A and B for Service Mode.  Generally you won't need it, but the choice is yours.  Consider doing a decent job of making this cable up.  It will be around for a while.

So, the TX/RX are jumpered together onto Pin G? Thanks in advance,

Steve B.

[GaryDoug]

8 minutes ago, Steve B. said:

So, the TX/RX are jumpered together onto Pin G? Thanks in advance,

Steve B.

 

Yes

Edited November 8, 2022 by GaryDoug

[justgary]

1 hour ago, Steve B. said:

So, the TX/RX are jumpered together onto Pin G? Thanks in advance,

Steve B.

Use the diode also on the orange wire.  The newer USB adapters seem to need it.

[Wakester02vlx]

I know this is an old thread but it seems to be the best place that I’ve found to ask this question. 
 

 I had a question about something I’m seeing while scanning for live data, every now and then while observing the data, it will throw a random dtc for a split second and then clear. Wondering if this is normal or is it something that’s going on with my ecm, been trying to hunt down a random stalling issue lately on my 325 monsoon. 

[justgary]

Do other values such as RPM have a glitch also?  The ECM data should be pretty solid.

Check the ECM data connector to make sure the ground pin is good.

[GaryDoug]

15 minutes ago, Wakester02vlx said:

I know this is an old thread but it seems to be the best place that I’ve found to ask this question. 
 

 I had a question about something I’m seeing while scanning for live data, every now and then while observing the data, it will throw a random dtc for a split second and then clear. Wondering if this is normal or is it something that’s going on with my ecm, been trying to hunt down a random stalling issue lately on my 325 monsoon.

It's normal. Sometimes there will be other brief glitches. I ignore them.

Does your engine have a manifold air temperature sensor (MAT)? The ecm is showing none installed (or defective).

[justgary]

2 hours ago, GaryDoug said:

It's normal. Sometimes there will be other brief glitches. I ignore them.

Does your engine have a manifold air temperature sensor (MAT)? The ecm is showing none installed (or defective).

I think only the big block engines in those years had MAT sensors.

[Wakester02vlx]

3 hours ago, GaryDoug said:

It's normal. Sometimes there will be other brief glitches. I ignore them.

Does your engine have a manifold air temperature sensor (MAT)? The ecm is showing none installed (or defective).

My 325 monsoon does not have one I believe.  Unless it’s integrated into the map sensor. 
 

and yes it does glitch out on other values as well, when im looking at the trend/chart section, occasionally whatever point im logging will either glitch up or down briefly, and it does it to all four points that are being charted. 

[UWSkier]

Glitches normal. My boat runs like a top but I see those random glitches too. I just discard those outliers from the output sheet 

[Michael23LSV]

On 4/27/2022 at 3:55 PM, justgary said:

I just wanted to tidy up the information in this thread so a person could know how to build a cable without chasing a bunch of posts.

Purchase list:

• TTL-232R-5V-WE - USB RS232/5V TTL Cable (do not get the 3.3 volt cable!)
• 12045808 - Delphi Connector Housing (MetriPack 150 series)
• 12124264 - Connector Lock (cover)
• 12045773 - Pins (You can figure out how to crimp them with pliers; buy spares)
• 15324973 - Cable Seal (Not required, but the wires fit better with them; one needed per pin)
• 1N4148 - Silicon Diode (any silicon diode should do)

The wiring diagram is simple:

Except that you also add the diode inline with the orange wire.  Put the cathode (with the stripe) toward the USB connector.

Also think about whether you want to add a switch to jumper pins A and B for Service Mode.  Generally you won't need it, but the choice is yours.  Consider doing a decent job of making this cable up.  It will be around for a while.

Just ordered all of the wire parts, @GaryDoug. Thank you so much! What parts would I need to make the Service Mode switch? Stoked to finally clear some engine codes myself! 

Edited July 8, 2023 by Michael23LSV

[GaryDoug]

25 minutes ago, Michael23LSV said:

Just ordered all of the wire parts, @GaryDoug. Thank you so much! What parts would I need to make the Service Mode switch? Stoked to finally clear some engine codes myself! 

You would need a simple toggle switch and a wire added for pin B. Connect the switch to pins A and B. Note that that switch cannot be on while the scan is used.

[UWSkier]

On 8/6/2020 at 10:23 AM, UWSkier said:

Fun with data.  Got some clean runs this morning to do some plotting of GPH vs RPM.  This is a Monsoon II with just me and about 150ish lbs of ballast to offset.

Also seems like the new fuel line, filter, and pump setup is working great as my WOT RPM was 350 RPM better than last time... though I was running without the doghouse today so there was no limit to cool air accessible to engine.

Red line is a moving average of the blue data points.  There's a surge in the midrange because those were holeshots.  Looks like right around 10.5 GPH for most slalom speeds.  22 GPH at WOT!

@Woodski