97 shortie. 3.0 245,000 miles.
I've already cleaned the throttle body and the idle air control valve. Throttle position sensor reads 5 volts, good ground, and a smooth voltage increase from idle to wide open throttle and back down.
Which of these codes is most likely to cause erratic idle? Mostly in the morning.
P0340 Camshaft position sensor.
P1443 Evaporative purge flow sensor.
P0401 Insufficient EGR flow.
P0171 Air/fuel ratio is too lean or rich for PCM to correct.

I doubt it's number 1, and number 4 seems too general to be any use.
I'm leaning toward number 3. Seems I read somewhere that the tube from the exhaust gets plugged up.

This started when I disconnected a plug from the blue air bag box to get rid of that beeping. Coincidence?

Any thoughts?

 

Your cam sensor is going out, I would replace this before it dies completely before it leaves you stranded. This is where the computer gets its info to fire the coil.



This also indicate a vacuum leak which would also cause the throwing of the EGR flow code and possibly the Evap code.

 

Hot unplugging of PCM connected components can cause false codes and damage expensive PCMs.

Disconnect both battery cable leads and touch them together for 10 seconds to bleed off charge in system capacitors. Dumps volatile stored codes memory, also learned parameters for your systems sensor variations and drive style.
Check to see what codes come back.

Any of those common Aero codes will cause idle issues.

 

I vote vacuum leak with 245K miles. Also,clean the MAF sensor. don-ohio

 

If it was a vacuum leak, it seems like it would do it all the time. Last Friday I drove it about 8 miles in city traffic and it ran just fine.

 

[QUOTE=93nighthawk;17141855]Your cam sensor is going out, I would replace this before it dies completely before it leaves you stranded. This is where the computer gets its info to fire the coil.


Do you mean the black cap with the three wires? I have an old one from when I had to replace the complete assembly because it was leaking oil up the shaft seal.

I read somewhere on this site that the engine would run even without the cam sensor.

 

Nah,baby,Nah! Vacuum leaks appear and disappear with engine temp a lot of times. Do n't rule out vacuum leaks OR MAF sensor dirty or bad. don-ohio

 

Vac leak . Check vac lines, pcv . May be intake

 

Bought some CRC MAF sensor cleaner and sprayed the MAF sensor as per instructions.
Changed the cam sensor with the one I had on hand. Like to never got the engine cover back on.
Replaced the Evaporative Purge Valve. Evidently this is a pretty generic part. Even Walmart sells it.
Seems to be running okay now.
Had the codes checked again. Only one.
P0402 EGR flow at idle fault.
Pretty much the same as P0401 insufficient EGR flow.
This vehicle rarely goes more than 5 miles from the house.
I think I'm done.

 

Hope you got her fixed! Good job! don-ohio