Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I am back. Had to stop working on veh. The reason I was reading erratic vac was because I had it connected right next to the purge vlv. So I was reading the actual switching of the purge solenoid. I tested the purge vlv and it pass all the tests. Totally eliminated the vlv, but of course I have a PO443, now. Vacuum reading, now, is 21" vac .maybe it will drop 1/2",but other than that, it stays at 21" vac.Veh still has the cut out on and off, not as bad, but, still there. As far as the fuel trims, still high, LT, -25% and ST at around 0%, at times reads +3, -3%. The cut out or miss is not steady. It misses for a second or two, then, it runs normal, then it repeats it again. If the chain jump, would it be reading a vacuum of 21"? What would be my next move?
With the vac reading steady at 21 hg there is no valve timing issue. So your ok there. What are your maf and map sensor readings, intake air temp readings, engine coolant temp readings at koeo (engine cold) and when koer engine is warmed up idling after 10 minutes? Do any of them glitch out (drop to -40 degrees) or voltage drop to 0 on signal wire for those sensors when warming up or koeo? If one of them do then that would be the cause of the rich long term fuel trims.
