ISC looks pretty robust. Not sure if they are prone to sticking or not.

 

https://www.atkinsrotary.com/store/9...A1-20-661.html


Probably got it from Atkins.

Or IRPerformance:

https://www.irperformance.com/produc...t-n3a1-20-661/

 

As far as I know, I can now with a lot of relief finally say that it's finished!

We tried the "new" ECU, and discovered that it, just like the original, were running perfectly fine, and neither were registering any codes,
nor were they ignoring the A/C and electronic load, so we ruled them both out for the time being.

Since we'd replaced most of the solenoids in the first place, and the crankshaft sensor most likely would have been acting up across the range if it was faulty,
I decided to just go for it and get a new ISC valve, since the car has taught me it was probably gonna go down the line regardless.

Thankfully, it was right on the money again with the ISC call - the spring inside it was pitch black, compared to the almost porcelain white on the new one,
and had most likely gotten stuck, at least partially.

We replaced it and the gasket, reset the ECU, and tried to start it again.
This time, the fast idle was exactly what I could hope for, still popping a bit, but heavily reduced compared to before, and noticeably smoother just by feeling vibrations on the engine.
I've read gentle popping/pulsing just comes as a side effect of the 13B, so I'm confident it's about as good as it's gonna get, especially with no proper muffler.

I was completely lost in every conceivable way doing this for the first time, so thank you both so much for your time and help, I massively appreciate it!

 

Good to learn about the ISC as a possible issue. Get a nice muffler.

Join the RHD nation.

Post some pics here.

https://www.rx7club.com/3rd-gen-gene...1148527/page6/