Has anyone got experience in switching from EI to JPI engine monitors or CHT monitoring systems?

I just did with no other changes to the engine - looks like my CHTs are on the order of 20-40 degrees warmer in similar OATs and IAS.

I called JPI and went through my troubleshooting steps with them and it looks like my new reported temps are accurate.

The EI probes were the ungrounded type, the JPI probes are the grounded, spring type. Both are bayonet style.

I noticed that all but one of the old CHT probes was only finger-tight, but they were ungrounded so I don’t know if that would matter much.

One possible difference is that the JPI is grounded to the engine block and the EI was grounded under the dash. But I’m not sure if this would matter since the EI probes are ungrounded and can’t make a ground loop.

Just wondering if anyone else has seen this, too. I’m happy with the new EDM 350 and glad I’m getting accurate temps now, just curious as to why there was a difference.

Well, I did some more wrenching and research and I definitely have exhaust leaks at the exhaust ports. 3 are worse and 1 is pretty minor.

Apparently those can cause falsely high CHT indications.

My next (in a never-ending list) project will be to reseal the exhaust stacks.

I wonder if the grounded probes, with their faster response, are more susceptible to this false indication.

Either way, I think I have a path forward.

Did you ensure you set type J vs K correctly in the box?

White/Red is a J-type
Yellow/Red is a K-type

Yes an exhaust leak can cause higher readings, but this should be obvious. Hopefully any small exhaust leaks you may have will not have eroded the face to the point of needing welded and refaced.

Timberwolf wrote:Did you ensure you set type J vs K correctly in the box?

White/Red is a J-type
Yellow/Red is a K-type

Yes an exhaust leak can cause higher readings, but this should be obvious. Hopefully any small exhaust leaks you may have will not have eroded the face to the point of needing welded and refaced.

They’re K-type: yellow/red. Came with the new box and this one doesn’t have provisions for J-type that I’ve found in the programming menu.

There was a white dusting around the port, and all over the face of the head that the CHT probe plugs into. I hadn’t noticed it before and I’ll be fixing it real soon. Hopefully I caught them early enough!