2G Rough idle

[intense593]

I have 97 GST. The car is idling rough and it surges. I did find a bad IAC/ISC. I replaced the valve and spark plug wires still same issue. Any one have any ideas what the problem may be? Any help would nice

 

[biker_joe89]

Boost leak test?

 

[91awdtalon91]

Could have some vacuum leaks as said before.

 

[And_44]

Vacuum leaks. Intake after your maf not plugged up? Are you recirculating your BOV? BISS screw? Remember to ground out your system any and every time when told to by manual.

If I remember the cycle of surge it's because your ECU try's to get it to the factory idle but when the the 02 sensor see's you running to lean (lean because of to much air incoming and not enough fuel) it ads fuel and it raises your idle, then it try's to cut your idle and cuts your fuel. So you get a vicious cycle going of to much to little.

Long story short check for any spots before your combustion that would allow unmetered air to enter. Make sure O2 sensor is in good condition. Then make some adjustments to the adjustable parts of idle system.

 

[99evo3gsx]

Is your air filter clean? I'd check that too. I had idle surge and found a vacuum line disconnected but the surge didn't go away completely so I cleaned my air filter with a k&n recharge kit and it fixed the problem. I've only had that filter in for 2 summers it was a lot dirtier than it looked.

 

[volkerding95GSX]

Have you messed with anything? When I first got my DSM I was stupid and took the honeycomb out of my MAF. I idled rough until I put it back in.