Ignition coil

[juliolop]

Days ago I purchased one similar to mine in autozone, it came with a label ...use with external resistor... And I was recommended to take it back.
Now I received the exact replacement from Sierra and has the same label. Use with external resistor except when it's used with thunderbolt ignition systems
Does this mean the autozone coil would have been used????

 

[thumpar]

What engine do you have? Serial number would help too.

 

[juliolop]

2001 Mercruiser CID 305 5.0L carburetor 2BBL, electric fuel pump and ICM in port exhaust elbow.
SN 0M322975

 

[alldodge]

I'm the one that told you that, and I'll say this. You went to Autozone and the coil had that label on it. You need an HEI coil with the TB5. Your engine will run with the Autozone one and also with the Sierra one, but will it run at top performance. At least Sierra says it can be used with the TB5, but Sierra is not the highest in quality. Your part number for the correct coil is 300-8M0079202

http://forums.iboats.com/forum/engi...board-engines-outdrives/10072194-2001-305-cid

Sierra also says their coil will also work with the ones below and it will, but how well.

• Crusader - 37068
• Mallory - 9-29701
• GLM - 72115
• Pro Marine - 64570
• Redline - RL5438

 

[gm280]

When any spark coil stated to use an external resistor, that means if you allow the supply voltage/current to work across the coil's primary to ground without any current control (an external resistor) the coil will eventually over heat and either short or open inside. The external resistor limits the current going through the coil to stop such damages. The voltage is still available, so you do get a higher output voltage, but the amount of current is controlled. JMHO!

 

[juliolop]

I understand both explanations ad thanks to you guys, but Sierra coil shows up as direct replacement for 300-8M0079202, what can I do?
Can I use this Sierra coil?

 

[alldodge]

Can I use this Sierra coil?

Sure, I'm just saying that Sierra is not always a quality part. It may last a long time, and then again it may not.

Also Sierra is saying it is a direct replacement, no other manufacture is confirming it

 

[juliolop]

ok AllDodge, thanks
I'll use it at least for a while, it's new, I will monitor the temperature of the coil regularly, and will replace for original at first opportunity.
tell me something, how do you identify TB4 from TB5, I though TB5 used a knockout sensor and module, but mine according to the papers is TB5 and do not use them.

 

[alldodge]

ok AllDodge, thanks
I'll use it at least for a while, it's new, I will monitor the temperature of the coil regularly, and will replace for original at first opportunity.
tell me something, how do you identify TB4 from TB5, I though TB5 used a knockout sensor and module, but mine according to the papers is TB5 and do not use them.

The difference between them is the module and how you time them. The TB4 is set rpm around 650'ish and adjust timing to 8 BTDC. The TB5 uses a different module and needs to be set by putting the engine is base timing mode by grounding the purple/white wire. Now the reason as Fun Times puts it, since you have a 5.0 and an alpha drive they didn't install the knock sensor. Kind of like buying a truck and not up scaling it for the bigger engine and chrome package.

If you got the 5.7 and the Bravo drive it would have had it

 

[juliolop]

my module is 861459T1
and in some websites 861459T02 is shown as a newer PN,

 

[alldodge]

my module is 861459T1
and in some websites 861459T02 is shown as a newer PN,

Agree, it is a TB5 and the 02 is newer

861459T02

ICM MODULE, Ignition Control Module

861459T1

(5.0L Alpha)

 

[juliolop]

ohhhh you're fast this time... really thanks
next doubts then.
If I have a TB5 I'm suppose to ground this Wht/Purp wire to set the module in Base Timing Mode in the timing procedure, isn't it?, is this not the wire that come from the knock sensor?, remember I don't have this sensor in my engine, I really though it was TB4, all of this is so confuse!!!!!!

 

[alldodge]

Not White/Purple, it is Purple/White (purple with White Stripe) ground to set base timing mode. The knock sensor wire is solid blue (1)

 

[juliolop]

thanks again AllDodge
by any chance do you know where to find the internal schematic for the ICM ?

 

[alldodge]

by any chance do you know where to find the internal schematic for the ICM ?

No, not a clue

That could be why no one else is make the TB modules

 

[juliolop]

ok,
I was thinking some similar should exist for car applications, any way to find out a cross reference?
thanks anyway

 

[airshot]

I am surprised that no one on here has recommended the flame thrower ignition coils for you. I was having coils problems a few years back, kept overheating and burning them out so.....it was recommended that I get the flame thrower performance coil from summit racing and let me say this......I will never go back to a stock coil again. Can handle the voltage easily, no overheat, hotter spark, easier starting, noticeable performance improvement.

 

[juliolop]

ok airshot thanks, but what kind of engine do you have? any specifications or PN for this kind of coil?, what does make it different?
thanks

 

[airshot]

I have a 3.0 140 hp. I went thru three coils inside of two years then switched to the flamethrower and never had another issue. I have the electronic conversion (no points) and that calls for a non resistor coil. Just went to summit racing website and picked out the flamethrower non resistor type canister type coil and had it in 2 days. All for less than 50 bucks. Stock auto type coils do not last long, they get burned up by the higher voltage from being non-resister type, at least that has been my experience and from what I have read on this forum....the opinion of many others as well.

 

[burtonrider11]

I am surprised that no one on here has recommended the flame thrower ignition coils for you. I was having coils problems a few years back, kept overheating and burning them out so.....it was recommended that I get the flame thrower performance coil from summit racing and let me say this......I will never go back to a stock coil again. Can handle the voltage easily, no overheat, hotter spark, easier starting, noticeable performance improvement.

Thanks for the info. I have a new (to us) 1997 Starcraft 2010SS (Merc 5.7 2bbl alpha) that I have been slowly changing out parts. I have new plugs, wires, cap and rotor. I am thinking a coil would be a good upgrade as well. Boat runs great when running, but starts hard when cold. I think it is more of a choke setting issue, but a new coil probably wouldn't hurt, current one is 18 years old.

Did you notice better IE quicker starting with the coil and what performance gains did you see? Top end, better hole shot, idle etc? Not that I really am looking for any gains, but i'd take them For $40, I don't think I can go wrong. Thanks again for posting this!