Here is my situation and a little bit about the car...
Car when sitting in traffic or idling for a bit seems to have a surge from idle (600rpm) to about 1000 or down to 300 or so. It doesn't die and if the rpm is increases to 1500 for a short bit it goes away for a bit them comes back. The one thing I did notice while standing next to the car is that it started to surge when the fans kicked on. I did do a test in the driveway and it did idle a bit rough when the fans kicked on but not bad. When they kick on there is a lot of heat pulled into the engine bay which is normal but is there anything that be affected buy the direct heat increase?
2002 wrx wagon 104k
Cat less up pipe, turbo back Cobb exhaust, professionally tuned at PRE racing in Portland Or
No AP installed to log
We picked up the car in dec and have not had it long so not sure if the problem existed all along or just came up. only comes up when warm outside.
During tune we were told the fuel pump had low pressure so it was just replaced by me, 255 wallbro was installed with little effect. Also fuel filter. The surge now seems less violent and a bit smoother.
Any ideas oh wise ones?? Looking for some direction on how to fix.
Thanks in advance!!!