Help ive tried every thing i can think of and i still cant solve my problem
my car a 79 ford pinto with a 2.3 c3 auto tranny has a hard miss idleing at a stop light if i sit for more than three seconds but when i do 70 or anything about 5 mph it runs like a dream
i took of the carb and cleaned it one day and it started to do what i described so i checked every thing and finally i unpluged the dist. advance from the intake and pluged the hole and it stoped doing it so what im trying to fig out what is wrong could the advance on the dist. be leaking or is my carb leting in air ??
thanks ahead of time
lost and found
Have you checked all the vaccuum lines? Also have you checked the vaccuum advance unit to see if the diaphragm is good? Have you checked the timing with a light?
My 78 4L/4 Spd does this intermittenly -- it seems to be almost weather related. Runs great about 75% of the time, but misses HARD the other 25%.
It really does sound like a simple vacuum leak is the culprit. If I had to bet, I'd lean towards one or more vacuum lines, possibly a leaky brake booster if you have power brakes, or even vacuum switches, rather than the base gasket of the carb.
Any vacuum leak would be most noticible at curb idle speed as then the percentage of air leakage would be the greatest as compared to the total air needs of the engine.
To make the job easier, you might want to pick up a set of rubber vacuum plugs from a local auto part store. They do come in handy, so even if it isn't a line that is leaking on this one, you will probably be using them through the years on other engines. I got mine many years ago, but they should still be under $10. For an engine of this vintage, you probably will not have a lot of lines, so one set will probably be plenty.
These usually come on a ring with several matched sets (6 or so) of different color coded male and female plugs, and are meant to be used to identify the various lines when disconnecting vacuum lines so that you can reconnect them without a big hassle.
Using the plugs, start disconnecting vacuum lines and plugging them at both the line itself and the nipple to which it attaches. You should be able to quickly rule out the lines that are OK, leaving you only a few to investigate further.
By the way, with any car this old, if you do find one cracked or loose vacuum line, there is a good chance that several others are very nearly as bad, and may crack enough to start leaking or even break off when directly stressed, so you really might want to think about replacing a bunch of them, just following good general preventative maintenance principles. The rubber coolant hoses and belts tend to be left on too long as well.
when i got the car some one had tore into the vaccume lines and disconected stuff so i didnt know where anything goes i just put it back together and it ran alright then i messed with the carb and it started to miss there arnt any switches left on the vac. lines now but its on time with a timing light i dont know how to check the diapram on the advance