QuestionQUESTION: I have recently repleced the fuel regulator,O2 sensor, TPS,removed and cleaned the throttle body assy. setting it up to the manual instructions with the distinct click at opening, and repaired several chafed wires that were open.
My question is after it starts it idles high then settles, then idles real low and either stalls or goes up high again.
I pulled the idle air control valve and bench tested it, opens and closes. There is not an idle adjust screw on the 89. AND I have been told that the ECU controls base idle...
Any help would be appreciated as I am disable and cannot afford to take it to the dealer.
Thanks for your time.
ANSWER: Danny, thid ones easy. Put everything back together. Pinch off the the stabilizer air tube and set base idle @750-850v rpm. If you still have problems, I would suspect the IAC valve itself. As they wear, they get a little slow responding. Idle up on starting is normal. After a few seconds, it should drop down to 9-950 RPM. Yes, ECU controls base idle with a few input suggestions. HTH
Mark
---------- FOLLOW-UP ----------
QUESTION: Mark,There isn't an idle thumbscrew adjuster on the 1989 240. There is only the throttle control stop screw. I adjusted the stop screw per the manual so that the TPS "clicks just as the throttle butterfly opens" If I adjust the idle by the throttle lever stop screw won't that mess up my TPS adjustment?
ALSO, the battery is 7 years old and died on me during my escapade in troubleshooting, before it died there was only a 1 1 1 code. Prior to my doing the aforementioned work on it the engine code indicated injectors and also rich or lean condition. The codes cleared out by themselves after the initial work that I did. Is that normal? I love this old tank, I really hate to shoot her...
Regards, Danny
I really appreciate your help here.
Answer Danny, God no, don't shoot her. Just kick her in the butt ever so often. You are correct though. It's not a TPS which stands for throttle position sensor in it's true form. It does however act as an idle switch. When it clicks, it sends a signal to the ECU to tell it the vehicle is off idle. It has no other function. This disables the IAC (Idle air control) motor and idle is no longer stabilized because you are not idling. Make sense?
I'm trying so hard to remember on these old girls. I thought there was a plug in the base of the throttle body you remove to access the air bleed screw? Maybe I'm remembering Quadrajet carburetors????
Seriously though, Check with an ohmeter to be sure the idle switch is opening and closing despite hearing the click. Make sure it is good electrically. Ignore the 111 code unless it comes back. Then let me know. I'll try to help. Check real hard for vacuum leaks, especially the intake manifold gaskets. VERY common. HTH
Mark
