donbrew

It is just a diode wrapped in rubber. Looks like a Xmas tree light bulb that has been blacked out. It is really hidden good.

skysailor

Temp sensor must be OK because the displayed temp is right on.
I'll be running down the brake vacuum lines and O-rings and I have a new check valve on order.

Used-Abused

I am by far no car Guru but I have had my fair share of used cars and to me I had a coil plug issue that cause the same symptoms

skysailor

Thank you for the suggestion and I will keep that in mind. But I will mention that when I have been able to catch it setting a code I get the code for misfires on all four cylinders which I am guess would rule out a single plug coil?

Oldblue

Check the ground wire at the back of the cylinder head on the driver’s side.



Just down behind the head , below the valve cover



Here’s the same photo, you can barely see that wire.

skysailor

Will do! Thanks for that Oldblue! :)

Oldblue

Oldblue sure was clean back then!

donbrew

P0300 does not mean "random misfire" or "misfire on all cylinders"; it means "unidentified misfire" or "seems like a misfire". If you had misfire on all cylinders you would have all 4 codes (P0301-P0304) and sometimes the P0300.

Don't rely on the titles of OBD codes.

Used-Abused

The issue I was having never threw a code and it was on a Ford but I went months looking for the issue

skysailor

Hi donbrew, Thanks for that clarification. Yesterday I checked the ground wire as suggested by Oldblue and it appears to be fine. No rust or corrosion and fastened solidly. Did not have the tools with me to remove it and inspect it more closely but plan to do that. So I started the engine and as it has been in cool weather it started and idled properly. On a hunch I turned the engine off and immediately re-started it and the old symptoms reappeared. I did this repeatedly about 5 or 6 times and each time the idle after starting was rough and 50% of the time the engine stalled out. So I then used my code reader to see if there were any codes and I found 4 pending codes: P0068, P0101, P0172 and P0300. Since I have replaced most if not all of the actual sensors and valves that would cause these codes it seems like I have an intermittent vacuum leak somewhere. Would you agree?