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Honda guru's, need ignition help


ross2004
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Car in question is a 4th gen Prelude, H22 engine. We keep killing the ignition control module inside the distributor- 3 in 7 races. It seems to be a fairly common problem that a lot of people mitigate with either a COP conversion or a CDI ignition box, but we don't have the points for either. Heat seems to be the killer, so I've thought about moving it outside of the distributor housing and in to the cabin with large heat sink. Anyone dealt with this and have a good solution?

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Where are you sourcing your parts?  I have had bad luck with durability using non-OEM or OEM supplier electrical parts with Hondas over the years.  We haven't had control modules issues like yours (but we have a non Vtec B20 so Apples/Oranges) but are using OEM parts.  I would try and track down a Hitachi made module if you don't have one. 

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I know it was a common problem in that era, when I was at a dealership. A lot of cars got recalled, the replacement units seemed to work better. Are you using O.E. parts (if available)? and double check you're using the correct part for your application. Some cars Had distributors from multiple vendors (Hitach, NEC etc.) they might use different igniters? I don't seem to remember ever needing to do multiples on the same car.

-Good luck

 

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We’re using an OEM distributor, and the last ICM I bought was Delphi brand which is supposed to be a re-boxed Hitachi (OEM). I can try buying an actual Hitachi ($$$). 
 

Interestingly, some other Prelude racers have had this issue and it was solved with a new wiring harness. So maybe I could run new wires for the coil and ICM, I’d like to avoid plopping down $700 for a new harness. 

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I've had this issue with B series distributors as well.  As previously stated OE parts help. As does air flow to keep the temperature down. One note on air flow the distributors also need to be kept dry. I've had misses develop when they get too much moisture. 

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The issue seems to be heat.  There are options to run an external coil that could help.  I played around with the idea of mounting a large CPU heatsink on the housing and even considered a CPU fan running on the heatsink.  I ended up ditching it all and just going COP at the end so that I could remove a common weak point.

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It's an external coil already, thankfully.

 

I was digging through the ignition wiring more last night and found hidden inside the factory loom one of those Scotchlok wire taps the previous owner used on the power wire to the coil (which then powers the ICM).....could be on to something.  

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