1987 Chevy Misfiring when cold

[ericb]

Rich-The ground strap between the passenger side head and firewall is in place.  I cleaned both these connection points extremely well.  I have not had a chance to check the specific vacuum line you referenced.  I will try and take a look at that.

Roundhouse-I have not tried unplugging the oxygen sensor.  I will also try that and see what happens.

Thanks for the suggestions.

[87 Wrangler]

Thanks Rich for the link!! My truck has surged for 25 years! Maybe I can finally fix it!
 

[78BIG-TEN]

Only vacumn line on the back of tbi that I know of goes to the map.Usually a loss of vacumn here will cause engine to go rich.Tat being said I've seen carbon build up on the bottom of the tbi in the vacumn port causing a  restriction and even plugged up solid at pcv side

[ericb]

Rich-I unplugged the oxygen sensor.  This didn't take care of the misfire.  I will try and look at that vacuum hose.  Thanks-Eric B

[VileZambonie]

Holy Guacamole! You are way over thinking this. If you in fact have a cylinder misfire, isolate the affected cylinder and narrow it down from there.

If it's random and erratic then you need to do as BD said and check fuel integrator and block learn.

If you suspect it is a lean misfire, try misting a little carb clean in the tbi and see if it stops misfiring.