Idle Issues
 

A buddy of mine has the same car I do- a 1990 Red TII. He says that his idle fluctuates quite a bit (from the 750 it should be to 2000), and he said that someone posted where electrical grounds can cause this type of problem. Does anyone know the thread? My idle is sometimes 750, sometimes 1500 and sometimes it bounces between 1800 and 1100. It seems to be affected by the time of day as well. In the afternoon, it idles best (50% @ 750) It's only bounced around in the morning. This leads me to a temp sensor or a ground problem, but I could be mistaken. Any ideas?

Adjust the TPS, that should fix it.

I'm going out to try that right now. I did find some info on the adjustment procedure that looks pretty straight forward.

No dice on the TPS. Warmed the car up, pulled the intercooler, disconnected the plug and rang it out. I have 995 ohms A to B, and 715 ohms E to D. And let me clarify, sometimes the car idles beautifully. And not for a minute or two. I can leave it idling on my driveway for 2 hours rock solid at 750. Start it up the next day, and it's a different car. Hunting, idling high, etc. I don't suspect vacuum leaks, or the car would never idle at 750 solidly, EVER. I've been more of a piston or jet guy myself, but with a vac leak, the ECM has no chance of commanding the car to idle solidly at the correct RPM. With this type of vac leak, it will lean misfire and die, or idle high, nowhere in between. Please correct me if I'm wrong on rotarys.

BTW, the picture attached is the actual car. I think its worth the effort!

try a new bacv it also controls idle air

I already tore BAC apart before I joined the forum and cleaned it up. I do see an idle drop when I unplug it, so I believe it is working correctly. It also has an external supply line, which I have kinked/pinched off, with no change. I plan on buying the PVC pipe/fittings so I can see what is happening below the intercooler.

i say vac leak mine as it and everyonce in awhile it will idle steady but most of the time its all over the place.

I pulled the IC and built a 1 1/2" pvc bypass for the IC so I could see what was going on. Right away I noticed that the trottle shaft was a long way from the throttle stop. I was already running the car, and forgot to check where the cam roller was in relation to the marks, but I'd have to guess that it was a long way off. I warmed the car up, and started backing out the fast idle adjustment screw, and the idle came all the way down. I originally had the BAC idle screw almost turned all the way in, so as I was backing out the fast idle screw, the car almost died. I opened the BAC idle screw about 2 turns, and continued to back out the fast idle screw. I backed it out a total of around 3 turns.

I'm going to let the car cool overnight, and set the thermowax cam and fast idle in the morning (it's about 77 deg first thing in the morning right now in Arizona)

When I got the car, it had a blown rear chamber (ate an apex seal.) The IC was already removed, so I can only assume the guy that had it before me was screwing around with all of the adjustment screws. :icon_tup: