Ok on my 280ZX Turbo it's idling high after I "fixed" a few problems (leaky injectors, corroded connectors, disconnected spark plug wire - sorta - another story) and I also replaced the stock TPS with a 240SX TPS and an adapter bracket to mount it. The TPS is adjusted to work just like the 280ZX and it's off an automatic so I'm using the switch portion that the stock 280ZX harness plugs directly into.

Ok so the question is it seems to come down slowly from higher RPMs but it doesn't appear anything is sticking (linkage, TB, etc). If I try to stall it to bring it down from 1500 RPM high idle I can take it down to around 900 RPM and it will stay there. Does that mean that problem isn't likely a vaccum leak? I'm assuming if it was a vaccum leak it would climb back up to a high idle.

 

Did you set the idle contact point on the TPS? Also, does the 60mm adapter bracket have a port for the air regulator?

PICS!

 

I'm turning into a regular mechanic. Normally I do a single change then check but I just dove in tonight. Found the O2 sensor was disconnected (hooked it back up - no difference as I suspected). Changed a bunch of vaccum lines. They were crusty but I didn't detect any leaks. The Idle Air Valve (sorry don't remember it's real 280ZX name connectors were really green and cruddy. Cleaned those up and I'm pretty sure those were the problem. Unfortunately I didn't check after I changed the lines - just got busy cleaning the vaccum lines up. Anyhow she idols just fine now

I just have the 240SX TPS mounted right now. The TB is on the ported plenum that's sitting on my mountain of parts. I've been so busy working on the car I haven't had time to make room in the garage. I have the Gray's Garage 240SX TB adapter which it looks like he doesn't make anymore. Too bad - it was the only one with the port for the stock system.