Well guys i got the 502 mag efi (1995) installed. Plugged in my scanner to set timing. Then going threw the scanner i noticed it is all over the map at idle. And about 3000 or more rpms she goes to 41 degree advanced. No codes. What you think? Is it normal. Never scanned the engine before.

https://youtu.be/tgBYh_IFMyU

they use the timing too stabilize the idle speed.it will look like its going crazy.

Ok that makes some since. Once off idle the timing shows normal, goes up with the rpms..

I also found my tach is WAY off . 2k on the tach and the scanner shows 2600ish

You need to set the timing into base timing mode by selecting service mode on the scan tool or buy and use the timing tool that Merc sells. When set into base timing mode the timing stabilizes so you can then check and or set your ignition timing. It would very useful to buy a OEM service manual for the exact apps that you work on. Just saying.

Open the link and scroll down to EFI / MPI timing procedures. I post stuff and then try to find it in pic and better script form than I can write.

Here is the jist - scroll all the way down from link. Like I said select SERVICE MODE on the scan tool or buy the timing tool - the part number for the timing tool is listed in the link.

https://www.perfprotech.com/blog/art...-engine-timing

Just to add info for future searches.

My tools/ electronics: Mercruiser Rinda scanner,
Craftsman Professional Digital Timing Light ( my 95 engine only has the 0 mark, so advance timing light is a must)

Bump up rpms and set into service mode va scanner. ( last thing make sure your distributor is not off 180 degrees )

Dont worry about the scanner showing the spark going crazy at idle. (see post 2 )

Well I was able to test her out yesterday, But was a shorter day. About 4 oclock I blew the rew water pump. Water was spraying right out the pulley, and flinging water right towards the flame arrester. So I shut it down and was pulled in by the 33 OL back to the sand bar to finish out the day then pulled back to dock. Good news Is I have spare, so Ill swap it this morning and get back out today.

I think i over tightened the new V- belt causing it to burn up the bearing and seal. I tightened the chit out if it because last year It would sequel/slip when cold. Opps, I wont tighten as tight this time.

I am lost - are you saying that you were 180 out for installing the distributor ?

probably initially it was out.you know the drill,try to start,pop,pop pop,,oops,distributor in wrong.

Sorry I have not been able to watch the vid on You tube. My computer is having issues for the past week so I am going by what is posted.

Correct. First start up, was pop....pop...pop..saying WTF. Then I figured out I had it 180, corrected via moving spark plus wires, and she started right up. I was just saying WTF when I saw the scanner reading all over the map once I got it started and timed.