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4.3L Thunderbolt V Ignition

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tsinks23

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Hello all, looking for a little help. I am in need of a ICM part number
  • 861251T1 ICM MODULE
For a 04 4.3L Merc. I was hoping to find a used one for cheaper before I go out and order a new one for 600$

If that is not the case does anyone know of an upgraded system that would cost about the same amount and still be USCG approved? If I’m already spending the money I’d rather upgrade. Thanks!
 
tsinks23 said:
Hello all, looking for a little help. I am in need of a ICM part number
  • 861251T1 ICM MODULE
For a 04 4.3L Merc. I was hoping to find a used one for cheaper before I go out and order a new one for 600$

If that is not the case does anyone know of an upgraded system that would cost about the same amount and still be USCG approved? If I’m already spending the money I’d rather upgrade. Thanks!
Click to expand...
Usually you can find them on eBay used, but as more icms have become NLA that is getting harder to find. Green Bay prop used to list a lot of used parts not sure if they can help.

If all else fails a delco est is a common replacement and is relatively drop in with minor wiring changes. The original delco is est is a OEM quality system, used on some VP and mercruiser engines from the factory. There are cheap knock offs out there that may or may not be of similar quality. Michigan Motorz sells est systems
 
If it were me,
I would look for any version of the thunderbolt ICM for a V6, IV or V early version.
TB IV did not have the mean best timing or the knock sensor and module so some minor wiring changes would need to be made but it WILL work.

I believe the early TB V modules also did not have the knock system but were a smaller package design and also would require some rewiring but will also WORK.

Actually V8 TB V with knock will also work. The difference is when its fully advances the timing and total advance.

The Module doesnt care how many cylinders a engine has.
The only real difference is the timing, when full advance comes in and total advance and connector design.
 
kghost said:
If it were me,
I would look for any version of the thunderbolt ICM for a V6, IV or V early version.
TB IV did not have the mean best timing or the knock sensor and module so some minor wiring changes would need to be made but it WILL work.

I believe the early TB V modules also did not have the knock system but were a smaller package design and also would require some rewiring but will also WORK.

Actually V8 TB V with knock will also work. The difference is when its fully advances the timing and total advance.

The Module doesnt care how many cylinders a engine has.
The only real difference is the timing, when full advance comes in and total advance and connector design.
Click to expand...
I believe the TB V knock or no knock sensor is more determined by what engine it is on. Seems like even with the latest TBV modules the base 4.3 and 5.0 2 bbls I have never seen with a knock module. Seems like more so they come on higher hp 5.7s

I am pissed at MErc for how many TBV modules are now NLA, which dries up the used modules available. When I did my repower back in 2015-16 I was able to find them all the time for $200 or so on ebay not the case anymore.

You are correct that with a little rewiring and the right connectors any module will work. I ran my 5.0 with 4.3 and 5.7 modules to test it on a stand no issue.

really sucks that they are NLA or $$$$ as it is such a good system. Have had zero issues or need to rest my timing in 11 seasons now, just preventative cap and rotor and plug changes every 3-5 years
 
As Dieter mentioned, I would go with EST
No manufacture is required to keep spares after 10 years of last production, just what it is
 
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