So My truck decided it doesn't want to keep a steady Idle at just after midnight when I want to go home from work. I managed to get it home in one piece and pulled the codes. the ones that bother me the most are
11, no Distributor reference signal detected during cranking (check circuit between dist. and smec/pcm)
21, oxygen sensor voltage NOT fluctuating
34, open or shorted condition detected in Speed control Vac. or vent solenoid circuits


what would cause these??
How can there be no distributor signal when the truck fires right up??

and what exactly is the speed control vacuum and vent solenoid?

 

Does it idle OK when you first start it when cold? If so trouble shoot the O2 sensor/circuit. If not I would look else where first.

The explanations of codes is very general in nature. "No distributor signal" does not always mean the total lack of a signal but can also mean an out of specification signal that may result in intermittent problems or total malfunction.

Vacuum solenoids are located at the right rear side of the engine on top by the air cleaner. There are 3 solenoids in a row, air switching, EGR, and purge. They are electronically controlled valves. This is how the SMEC controls the vacuum to these systems.

 

It happens randomly usually when I first start the truck fir the day but it's also happened after coming up to temp. And sitting at a long red light. Would faulty canister purge solenoid cause any of these problems?