engine and drivetrain tii hot idle

[Andy74tii]

I have an interesting issue with my '74 tii. It idles pretty normally, around 1K rpm, after just starting. The longer I drive it, the warmer the engine gets, the lower the idle goes. It nearly stalls after about 20-30 miles driving at idle. Anyone else encounter this issue? I am afraid that if I just adjust the idle higher, it will run way too high at cold. I have disconnected the decel valve emissions stuff. should I disconnect the warmup regulator wiring?

[JsnPpp]

Hi,

There are several things you could do here, but upping the idle is the most easily reversible.

Your Tii *should* have modestly higher idle during startup, it's designed that way. Mine is around 14-1500rpm till it warms up and then it's around 1000rpm.

I would drive it till it's hot (make sure it's *completely* warmed up, which is not just when the water temp is horizontal - mine takes about 30 min for me to know that it's done) and then up the idle to around 900-1000rpm.

Next time you start the car from cold, yes it will be slightly higher, but then drop down slowly as it warms up. If it idles smoothly at the new settings you should be good to go.

If the car starts to idle at different rpms each time you come to a stop or it stumbles or anything else then report back and we'll see what we can do.

Oh, before moving the idle adjustment screw (outside of the tuna can) make sure to mark where it was so you can get back just in case.

Hope this helps,

Jason

[SteveJ]

I'd do some other basic things as well- a valve adjustment can make quite a bit of change for drivability. Plugs, cap & rotor? When was the last they were changed?

My 72tii was starting to rough and the idle was very low. I did a valve adjust and the motor smoothed out considerably. It had been quite a while since I last did a valve adjust.

Do some of the minor maintenance, then go through the basic tii tuning set-up. If anything, it will eliminate those items from your troubleshooting.