Let's see if anyone has any suggestions. I have a 91 crx with an LS swap and when I start my car it will run fine for a few minutes then sometimes run real rough then almost die, then it will rev up a couple hundred on it's own and be fine until the next day. It will also run rough while driving sometime during the first 10 minutes or so of drivng then be fine. Any ideas will be much appreciated.

 

Do all your rough running problems happen at idle? If i had to take a guess i would say either a MAP sensor, temp sensor, or IACV is not workign correclty. If you have access to a scan tool that will display live data, check all the sensors and make sure everything is fine (i.e. the engine temp isn't like -20 F)

 

It usually happens at idle but also sometimes while im driving, at low rpms.

 

Its your vacum lines going to your Throttle Body and Intake........trust me i had the same problem.......i will take pics of mine so you know where to hook them up ok

 

Also let me state it could be your head gasket too.......but more inlikely its your vacum lines.......but if it was a headgasket you would have antifrezze in your oil so......

 

Just as an update the ECU is throwing out code 43 which is fuel supply system, any suggestions?

 

I would suggest checking the fuel pressure. If you don't have fuel pressure check to see if ur fuel pump is running.

 

Well i replaced the fuel filter and the problem still isn't fixed, could it be the fuel pressure regulator and if so, where is it located?

 

fuel pressure regulator is on the fuel rail at one end or the other, should be a little aycorn looking thing