600SCi Misfire....
 

One of the 600SCi's (port engine) has a misfire, pretty sure it's on the inboard bank, BUT not throwing any codes on the Rinda scan tool.... I changed all the spark plugs Friday, but still have the mis-fire. Any ideas guys?
Thanks,
Dean

I had 2 coils replaced on mine, was fine at idle but under load and some rpm would break up. I replaced plug wires first, that didnt change anything.

Mercruiser / Mercury 300-8M0077471 IGNITION COIL
Fits the 75/90/115 (3 cylinder) OptiMax outboard beginning in Model Year 2004,
and various V‑6 2‑cycle outboards.
Also fits MCM 600SCi.

Maybe someone can confirm, but checking quickly it looks like these use the popular(for performance) IGNA1 coils.
If so, here are a few of a long list of IGNA1 part#'s from the popular performance aftermarket:
IGN-1A Ignition Coil
AEM 30-2853
Holley 556-112
Amp EFI DIY Auto Tune IGN-1A
Haltech HT-020114
Pro EFI HO 8005

Most can be found for around $75.00 and up. Mercruiser wants $160.00+
https://cimg4.ibsrv.net/gimg/www.off...9fa4481676.jpg

https://cimg4.ibsrv.net/gimg/www.off...75907f4edc.jpg

Don't believe the 555pcm will log miss fires as faults. Have you tried the coil output test with your scan tool? You will need a spark gap tester to hook onto your plug wires when testing. Also run an injector test with the scan tool. This will verify injectors are getting proper run command from the pcm. This test will not show if the injector is clogged, leaking or not flowing correctly.

Holley and most buy and sell the knocked off versions. I know this for a fact and Merc has the the Original plus they designed the original ones before anyone else. I actually know the guy whom designed them for MERC, The Ign 1 a coils

I have them as well the OEM Merc ones and they are in the classifieds for sale. And nicely priced. . There is a Service Bulletin as to why you need to change the coils out. The outboards experienced that first as it was causing PCM failure from the coils and so did the 600 sci and 700 sci. Matter of fact last month I fixed a 600 sci because the coils knocked out the PCM. Also Merc racing engines need to have an updated Bulletin performed and I have all that info on top of.. .

the Merc racing 600 sci and 700 sci experience the same as this plus they have an SB update . Here is the outboard SB of the Ign 1 A coils.

http://www.marinepartsexpress.com/Me...02007-25R2.pdf

https://www.offshoreonly.com/forums/...ls-market.html


and what a deal this is.

Thanks Guys, I'm headed back up to Mystic later this week, and I'll check out the coils/plugs wires....

BUP,
Once again, thanks for all your knowledge...., and if I need a coil, I'll be giving you a call!
Dean

Well, found number 2 coil is bad, the photo shows it next to a good one . Talked to BUP yesterday and he said it's called a secondary post failure https://cimg6.ibsrv.net/gimg/www.off...91b3afb43d.jpg

One of my 525s has developed a misfire over the winter. I fired it up last weekend, and idles fine, but won't rev properly. Getting to the coils is a b#tch on my boat, not looking forward to diagnosing this at all.

E32,
It's not easy that is for sure.....
Good luck with it, the easy way to find out which cylinder is misfiring is just fire up the suspect engine for about 1 minute, and just feel for the cold header runner....

I got lucky. Once the engine warmed up, it ran fine. I'm not sure how it was winterized, but after a few minutes on the hose, everything was fine. Then I took the boat to the lake, and everything was still fine. Feeling for the cool runner is a great tip.

Prob was a tad of condensation in your fuel very common from lay up... All the fuel filters need to be changed at the spring commission and that fuel examined ? and fuel samples from the gas tank(s) are very recommended about 3 times per year min especially at layup and start of boating ?

Coil replaced and misfire is gone, thanks BUP!