my 91 cherokee was runnin very rough loadin up after about ten mins and dying then it wouldnt start back up for a couple of hrs. i pulled the codes and all it showed was a 34 which was open circuit vaccuum. after checking all vaccuum hoses and switching the map sensor it is running a lot better and not dying and cranking every time. but i still have a check engine light sayin code 34 and yes i unhooked the battery. any ideas? it does idle a little spiratic but not bad

 

You'll have to take it to an autoparts store and have the code cleared with a code reader.

 

the line off of your MAP sensor may be clogged. Blow it out with high pressure compressed air. I reccommend you disconnect your battery for a minimum of half an hour, some people recommend to touch the battery cables together for 15 seconds to clear the computer.
I would also blow out the orifice in the Throttle Body that MAP vaccum hose connects to.

try these things and see if it works.
Maybe some other people will come on here and give you more ideas.

 

OBD1.. AFAIK the codes will be cleared after the battery is disconnected for a certain amount of time.
All code readers do is keep the CEL from coming on

Or, the OP could just leave it. If the problem is gone the CEL will turn off after 50 start and run cycles.

 

thanks man

 

ok stupid question what is a PO

 

sorry, meant OP
Original Poster

 

I have the same problem on my 93 XJ. Light just keeps going on and off.