2.3 Running really rich at idle

[chadzeilenga]

I've been trying to troubleshoot my 1989 Ranger with Dual Plug 2.3L

So far I've done the following
Fixed timing belt (was off by 2 teeth)
Replaced plugs & wires (#1 wire had a lot of corrosion on it)
Replace pass side coil (it was cracked)
Replaced Fuel Pressure Regulator
Cleaned IAC by filling it up with carb cleaner & letting it soak, then I blew it out with compressed air
Replaced O2 sensor
Removed catalytic converter

The engine runs great with 1 or 2 vacuum lines unhooked. It seems to lean out the mixture and I get a pretty good idle. With the vacuum lines attached it idles really rough and wants to die. When I hold the RPM's around 2k it is smooth and runs fine. It runs like this cold or hot.

Currently on the list to do is:
Clean out Throttle Body
Check timing again
Check the TPS

Does anyone have any suggestions?

Chad

 

[Zer0PSI]

It's probably a bad oxygen sensor. The same thing has happened to me. As for disconnectiong the vaccum lines; that will lean out the engine because their is unmeterd air entering the engine.

 

[chadzeilenga]

Brand new?

You mean the brand new O2 sensor is bad?

 

[4b316]

Check the wires up from the O2 sensor also.Have seen a new o2 sensor that was bad.Good idea to check TPS.

 

[Dave R]

Your '89 computer is quite capable of doing self-diagnosis. Have you checked the computer for error codes?

Just tossing parts at the truck in hopes of fixing it is really a waste of time, effort and money.