Driving me crazy!

[Lone_Domino]

I have a very stock 85 with a freshly rebuilt engine. It was dis-assembled when I built it so I don't know how it was running before it was torn down. Since I got it started it has had a slight miss to it and it will occassionally stall for a second or so. Sometimes it will do it 2 or 3 times in a row and then it will go several miles with no problem. The engine does not completely die, just stumble and the check engine light come on. I don't have any aftermarket parts, gauges or scan tool right now.

Where do I start? It is so sparatic that I don't have a clue. It is annoying as heck though for it to buck and stumble while driving.

Thanks!

 

[VernLee]

Vacuume Leak ????????????????????

 

[GNFURY]

you need a scan tool. Does it idle rough? Here is what I do. I had a bad/erratic idle in my car. Pop the hood and start up the car. Locate the mass airflow sensor, the throttle position sensor, and the IAC. If you don't know where they are, go here:

http://www.gnttype.org/maint/sensors.html

let the car idle, and then start unplugging the sensors one by one. If the way the car is running does not change when you unplug a sensor, that may be your culprit. I.E. if you unplug the mass air sensor, and the car dies, it is working properly, if the idle does not change at all, this sensor may not be working right. Is the engine "missing"? If so, you can do the same thing with spark plugs (be careful ) and the injectors. Same thing, if there is no change when you unplug, that may be the culprit.
Hope this helps. Let me know.

 

[Lone_Domino]

Found It!

Found my problem! The hot wire going from the battery to the alternator got mashed behind the a/c bracket and had also come in contact with the up pipe causing an intermitent short. It burned in to today on the way home from work. After I spliced it back together it ran great with no stuttering or problems!

Thanks for the advice. I still have what seems to be a slight miss at idle that I will try to look at soon.

Thanks!