Either you have a vacumm leak of some sort or a your TB butterfly is cracked open at idle, Very common . Check the tension of the throttle body's cable to the butterfly, it should have literally no tension.
OR your idle is not set correctly, there is DIY's everywhere on how to set it right using a ground cable to a connector etc etc.
RESET the ECU after you find either one of the above to reset fuel trims.
Happy DSM'ING.

 

Also you might want to try doing a boost leak test. If you don't know how to do one, just search it.

 

and he said that he left a wire by the throttle disconnected. I looked all around the TB and couldn't find what he was talking about. Can anyone help??

Only wires that go the the TB are the ones to the Idle Speed Control motor and a single wire that goes to a switch right by the connection of the throttle cable and elbow (I think the switch has something to do with the AC when the car is idled?).

If you have already done a boost leak test, and don't have leaks in your system, your symptoms sound common to idle surge problem DSM cars have when the idle speed control motor craps out.

I have an N/A 4g67 and I went through everything even replacing an intake manifold gasket which was crimped and causing a vacuum leak. I was still having surge issues until I replaced the idle speed control motor with one that worked. Great site that helped me was vfaq.com.

This is a common problem a lot of people post, as these cars are getting older, this is common for this to happen. Use the search function on this site. First search "boost leak test" and fix those problems first. Next search "idle surge." Those topics have been covered numerous times and will give you a great place to start.

 

Thanks for the ideas! I'll check for leaks and do some research on the idle speed control motor and then let you know what happens.

 

My ISC is doing the same thing. Simple fix.

 

What was the simple fix on yours? Was it just the ISC motor?

 

Yeah, most of the time it is. I just got on from a friend and put it on and fixed my idle surge problems.

 

Well, bad news. I ordered a brand new ISC motor and it's almost worse than the old one! Could it be something with my ECU? Someone suggested that I wipe my ECU so that it has no memory of the old ISC and give it a chance to get used to the new one. Would that work?

 

Unplug your tps and see if it stops. My car was doing that and when I unplugged the tps it stopped. I bought a new tps and now it idles perfect. You could also check yours BISS screw for the high idle if it doesn't stop. I was told to turn it all the way in until it stops then turn it out two and a half turns and that's the spot it is supposed to be.

 

The ECU could have leaking caps cause the car to run like crap. Take the ECU out and pop the top off and check inside for leaking caps or burnt smell. If your ECU is ok than thats one less thing you have to worry about. The ISC and TPS is could be a problem as well, check those and see if they are working properly.

 

Yeah, the BISS screw is actually completely missing on mine! I ordered a new one and it should be here in a few days. I can't imagine the BISS being the problem though. Wouldn't it just make the idle either really high or really low instead of fluxuating like mines doing?

 

Wouldn't it just make the idle either really high or really low instead of fluxuating like mines doing?

It will idle higher with the BISS missing. And could casue slight idle surge as the computer is constantly trying to adjust the fuel map to compensate for any extra air getting into the engine.

The first thing you must do is a boost leak/vacuum leak test on your car before attempting to diagnose any idle problems. A proper test can be found at http://www.vfaq.com. Any leaks in your system or air entering/leaving the system that the MAF isn't accounting for will cause idle problems. This is the easiest and typically least expensive thing to do and fix.

Also after you BISS is fixed (and you went through the steps of properly adjusting your BISS, also found on http://www.vfaq.com) and you still notice a problem. Back track your ISC installiation. There is an O-Ring that people forget about all the time that sits between the ISC and FIAV. Look here for pictures http://www.dsmisc.com/dsmweb-dw/pictures.html . It is something that can be easily overlooked when you are changing out ISC motors.

If you checked and double checked those all correctly, you should be ok. If you still have idle issues, you might have other mechanical problems wrong with your car not associated with intake/throttle body related.

I hope this clears some things up for you.

 

Nice input aferraro21, seems like we were telling someone else this same thing in a different thread.

 

Thanks, yea I'm pretty sure we were. The veterans on this site get tired of answering this same question all the time, so I try to jump in where I can. If I didn't have help from other people before, I don't know if I would've ever figured it out.

We just do what we can, and try to help the next person out. Another DSM on the road makes this world a better place (for mechanics haha).

 

Great, thanks for all the input! I'll do the boost leak test and install the new BISS and then we'll see what happens.

 

Just to be a little more specific too on the VFAQ site...

This is the boost leak test I was talking about http://www.vfaq.com/mods/ICtester.html .

Since you have a 1g this is the proper way to adjust the BISS http://www.vfaq.com/mods/BISS-1G.html (although you can adjust it without those steps, and still get decent idle, I recommend doing it the right way).

 

Same here as long as i hear about another DSMer on the road running good and boosting hard is all that i care about, i mean the search button is still useful but sometimes there's not enough detail. Good luck with the fixes and let us know how it worked out.

 

Just got the BISS today. Installed it and it's idling perfect now. Thanks for all the input!

 

I should also add in that you should address the IAC very soon, as a bad IAC can cause one of the drivers in the ECU to burn out.

 

Address the IAC how? I just bought and installed a new one about a week ago. Do I need to do something else with it?

 

No, if your car is running good now and idling the way it is supposed to and you replaced the IAC motor not to long ago than your fine. Happy DSMing.