Data link connector location

[kgarguilo]

FYI, my adapter like that for my MEFI 3 connector / adapter, came in the Kit from RINDA. I ordered the Diacom Diacom 94105 Kit - US. I purchased this in July of 2023

[Viper]

What do you need to check with the diagnostic computer? Are you having a runability issue?

[Punch'Eau]

Source of the post What do you need to check with the diagnostic computer? Are you having a runability issue?

I need to check if any codes are present and compare live datas for both engines. Starbord engine was dying sometimes when coming down to idle. I changed the timing control module and the problem is gone but when I put it to N from forward or reverse the rpm goes up from 750 to 1100.
I cleaned the throttle body and IAC and even swapped with port engine but no difference.

[kgarguilo]

If that is all you are after, a better purchase may be the Fox Marine or equivelant engine gateway. Check out my you tube video on the topic. The interface on android or apple is at 8 miniutes into the video.

Or watch the whole video, I did quite a bit of research prior to going down both roads meaning, I have both Fox Marine gateways and the Diacom software. I use the Fox Marine way more. It also brings all the engine data to my Garmin 8612.

[Viper]

I have a few questions;
To clarify; when you're in gear at idle, the rpm is 750 then jumps to 1100 when put into neutral and will stay there?
It does sound like an IAC or idle air issue, or a fuel delivery problem. Did you check to see if there is an IAC air filter in your application?
Have you done an ignition tune up?
I assume the new module you put in was OEM for your serial number?
Have you tried disconnecting the throttle cable at the TB and see if you get the same rpm result coming out of gear?
Did you try swapping out the TPS with the other engine?

You may also want to consider that it's an injector problem and do a cylinder drop test. Having said that, a cylinder drop test might not reveal if it's a leaking injector at idle. Either way, for their age, they may just need to be sent out for a professional cleaning. If you try to restart the engine after shutting down for 10 minutes, does she start up easily again?

[bud37]

There are a number of things at play here.... the least of which are the iac counts at idle needing to be in range so that iac valve can operate quickly in both directions, your mefi 3 may have a floating idle and a load compensating function. The hunting is generally the ecu trying to compensate, which can be seen on a scan recording.

As you can see from the preceding posts it is fairly complicated to get it right that's for sure.

[Punch'Eau]

Source of the post I have a few questions;
To clarify; when you're in gear at idle, the rpm is 750 then jumps to 1100 when put into neutral and will stay there?
It does sound like an IAC or idle air issue, or a fuel delivery problem. Did you check to see if there is an IAC air filter in your application?
Have you done an ignition tune up?
I assume the new module you put in was OEM for your serial number?
Have you tried disconnecting the throttle cable at the TB and see if you get the same rpm result coming out of gear?
Did you try swapping out the TPS with the other engine?

You may also want to consider that it's an injector problem and do a cylinder drop test. Having said that, a cylinder drop test might not reveal if it's a leaking injector at idle. Either way, for their age, they may just need to be sent out for a professional cleaning. If you try to restart the engine after shutting down for 10 minutes, does she start up easily again?

Thank you very much for your support.
Rpm will jump around 1100 just a second and dropback at 750 every time I shift from forward to neutral or reverse to neutral. Sometimes when engaging it drops under 750 but don t stall anymore like with old ignition control module.
Both engines always start easily anytime.
No ignition tuning done at least since I own it.
I tried swapping whole throttle body including tps and iac and no success.
I did nt try to disconnect throttle cable at TB but I could.
For the iac air filter, are you talking about the kind of tiny foam inside the TB at the iac? If yes there are none in either TB.
Upon your questions I missed about the ignition control module. I bought an automotive cause I tought this part would nt cause any difference

[Midnightsun]

The IAC controls your idle air. This is what it looks like.

https://www.amazon.ca/Control-Valve-Compatible-MerCruiser-Engines/dp/B08FYLZKMB/ref=asc_df_B08FYLZKMB?mcid=d144af4fa83335708b44f40092b7bb7e&tag=googleshopc0c-20&linkCode=df0&hvadid=706726017561&hvpos=&hvnetw=g&hvrand=5340987280069031180&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1002504&hvtargid=pla-962539035031&psc=1&hvocijid=5340987280069031180-B08FYLZKMB-&hvexpln=0&gad_source=1

[Viper]

I think his is the cylindrical type IAC. The one in the listing is for newer engines, post MEFI. The listing does have a pretty good description of it's function though and symptoms of a failure.

I haven't looked into the control module specs for auto vs marine but in general, there are some things you just shouldn't interchange unless you're sure the spec is exactly the same, otherwise you could be chasing a problem for a while or causing another one. Boats have a different ignition curve than cars with the same engine do, not to mention a number of other things. For example, the intake plenum alone that you have changes everything, it's design handles air totally different than it's auto counterpart and is a variable that influences the required spec of common components, use the wrong component and it throws everything off. In the end, it all affects the computer's main job which is to manage fuel delivery based on component specs it was programmed to work with. If it's a component that influences timing, or provides the ECM with an input (sensors), or is controlled by the ECM's output (like an IAC), stick with OEM unless you can confirm the spec is exactly the same as the OEM spec.

Don't know how long you've owned the boat but I'd consider an ignition tune up. It may or may not solve this problem but you can't be chasing a runability issue without knowing whether your ignition system is up to spec. Once it is, you can cross that off the list of possibilities. Pull your distributor cap and look for corrosion on the contacts inside, and look for cracks, carbon tracks, etc. in the cap. If you see any of these, the cap and rotor need to be replaced, and change the spark plugs too. At the very least, you'll have a record of when they were last done.

One other thing, that model MPI did funny things under low voltage, any computer driven engine will but those MPIs hunted, revved up (maybe to excite the alternator in a low voltage state), hard starting in that they would start but stall, etc. So test your batteries properly, make sure you have tight, clean connections, and make sure the alternator is charging.

[Punch'Eau]

Thank you very much again
The OEM ignition control module will go in as soon as I can. (Probably next season cause it s un fortunatrly time to pull out our boat from the water here)
I changed de plugs rotor and distributor cap already.
Thanks again