Idle Help!

[jason031479]

I got a great deal on a FRPP single blade throttle body, and put it on this weekend. I also did a tune-up (plug, wires, fuel filter, pcv, and oil change). I set the TPS to .985 and cleaned out IAC with some throttle body cleaner. I also made an oil separtor coming off of the pcv valve. After all that, everything seems to be running fine. However, the car now idles at about 1000 rpms, and sometimes hangs at about 2000 rpms before settling down to idle again. Also, after cruising at about 65 mph on the interstate, and then shifting the car out of gear a cruising down the off ramp, the idle surges between 1000 to 2500 rpms for a little while before settling out. Is the computer just re-learning everthing with the new throttle body? Should I unplug the battery and reset the computer? Am I getting some sort of vacuum leak from the oil separator? ---- Any suggestions / comments ?:shrug: :??:

BTW - 98 Cobra - X-pipe, Cat-back, c-springs, Cobra R's, steeda shifter - 28,000 miles

 

[jason031479]

anyone?

 

[RoadZOmbie]

Your IAC might need replacing. For some reason that seems to happen a lot after owners "clean" the IAC. Weird. Maybe some seal go bad? Try re-setting the computer. Hope this helps.

 

[jason031479]

Should I lower the TPS to something closer to .97 to avoid a dashpot mode problem? And do I need to disconnect the IAC while setting the TPS?

 

[Tabres]

Start with the easy stuff first.

Go back over all of the connections and make sure there are no vaccum leaks. I would think you'd be able to hear it if there were, but all the same. I personally would leave your TPS set where it is, although if you do change the setting you do not have to remove the IAC to reset your TPS value. Also, check and see if there is a tear in the gasket for the IAC. And do try disconnecting your battery, you never know, it might work...

To be honest though, I would put my bet on your IAC starting to go out...

 

[jason031479]

I'll take a look at the IAC again, and check for any vacuum leaks. I guess I should've left it alone, but I figured it wouldn't have hurt to clean it while I was doing everything else. I'll leave the battery disconnected for a while too.

 

[jason031479]

reset the computer and found a big vacuum leak on the oil separator that I made, car runs a little better, the rpms aren't hanging as bad, the rpms still kind of bounce around from about 900-1500 rpms as I idle to a stop coming off of the interstate and then they finally settle out to an idle of about 900 ... iac seems to be fine, should I dial in the tps a little closer to .97 and maybe clean the mass air sensor?

 

[STAMPEDE3]

You can try to lower it to avoid dashpot but it hasn't worked for everyone.
Keep in mind that dashpot does this to keep steering and brake pressure up when cruising to a stop.