So I just picked up another Miata this time a 91 NA6 with a no name supercharger, I say no name cause I can not find a logo, a sticker, a stamp or a serial number anywhere but I've also only looked on top of the SC and in my door jams.

So the car idled ok and I shouldn't have touched it but I wanted this boost gauge to work so I did some fiddling and blocked off the open air T fitting and attempted to adjust my idle air screw thinking I'll just turn it back if it doesn't work, well Nothing worked and now my idle is really slow to come down when I press the gas and pretty high about 1200 and I can't get it to come back down to it's original 1000 Rpm idle. Any help is welcome


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I think it's an old Sebring M45 based on the metal intake tube and unmarked outlet. Either way the kit is close enough to a Jackson Racing M45 (JRSC), with exception of the fueling stuff.

Not really sure what' shown here. The second pic looks like the Tee is still open...? If so, that's your vacuum leak and why it's idling high. I'd put everything back, and instead, tee your boost gauge reference line connected to the AFPR. That way, you're certain you're seeing the same boost pressure as the AFPR for future troubleshooting.

 

Looks like the fairly common old Jackson Racing supercharger kit, an MP45 from memory.

If you look up stuff related to that you should be able to get a bit of detail on how it's normally setup.

 

Yes the T fitting is open it came that way, so I did block it off and also removed it too while adjusting the idle screw but nothing seemed to change, so I just threw it back in and returned the settings, started it in the cold morning and it idled at about 1050 ok good drove it, idle good about the same, get to work and my idle sits high 1600 ok weird. And it has a slow return to idle, everything points to a air leak from reading everything on the internet so today I'll block it all off and spray around for another leak.

Another question do I need an ignition timing control or is that just something that could be added to help?

Ps, I got bad punctuation I'm still working on it.

 

If you don't have ignition timing control already on the car then you better hope the supercharger is worn out and not making much boost. Ideally you would like control over both ignition and fueling, as with a megasquirt. A used megasquirt 1 should be just a few hundred dollars if you have no money to work with.

 

Yup. That's a jackson racing M45 kit. It's a later kit since it has the flat pulley on the supercharger. You can download a PDF of the instructions to make sure everything is installed correctly. The bypass can should be hooked to the manifold just after the throttle body on the back of the supercharger.

T into the FPR line or the fitting on the intake manifold for the boost guage.

 

All the docs you'd need are here. Good luck.

https://sites.google.com/site/redcapsmiata/home/files