High idle after accellerating past 2k RPM then to nuetral?

5LTREATR · 08-04-2011, 03:17 AM

Just got an '02 SS Camaro M6 54K mi.(K&N CAI and Magnaflow Cat Back) and trying to work out this intermittent high idle problem. Here is whats going on normally idles right at 800rpm, when driving with the flow of traffic drops right down to idle, If I accelerate rapidly and then go to nuetral above 2500 rpm it will then idle at 1100-1300rpm and hangs in the rpm's longer if I rev it it sometimes stays at whatever rpm I rev it to for 10-15seconds or if I put it in gear and engage the cluth momentarily it will drop to the high idle. Then I can pull over turn the engine off for 30 seconds to 1 min and it starts up and goes right to 800 rpm, at that point I can rev it all I want in nuetral and it drops right back to 800rpm.
Things I have done to try to correct this:
1. NGK tr55 plugs
2. MSD Super Conductor Wires
3. All 4 O2 sensors
4. Replace cracked pcv hose by the t.b.
5. Cleaned MAF,IAC,T.B., Air Filter(Checked to make sure these where mounted and sealing correctly not to much oil in the filter)
6. New Battery (Left it disconnected overnight to let it relearn idle)
I am going to check for more vacuum leaks with carb cleaner thursday and replace the Idle air control valve, I would also like to know how to check the TPS sensor with my multimeter. Any info would be greatly appreciated. Other than that issue the car is great I have been wanting one of these for a while! Thanks for any help I will update this in the next day or so.

**Cutlass** · 08-04-2011, 03:31 AM

my PCV system leaked right here and its a common leak source. Not sure if thats what you already fixed.

There is also something built into the PCM called Throttle Cracker which raises the idle while your shifting. The throttle cracker rpm might not drop down until you have nearly or completely stopped the car.

5LTREATR · 08-05-2011, 12:33 AM

Yes thats the hose I replaced, as far as the idle dropping down it stays at the high idle and wont drop below 1100 until I shut it off and restart then it goes right to the 800. I am picking up a new iac valve friday and see if that makes a difference and also check the voltage readings on my tps. Next step will be to add headers (Bigger MAF maybe also) and go to Wong's Performance Engineering in Vancouver, Wa for a dyno tune he mainly works on Corvettes and F-bodys and has a very good reputation. Thank you for the reply!

**BLK2KSS** · 08-05-2011, 01:05 AM

In my experience when ever the car is moving, especially on the interstate, and I put it in neutral it will always idle higher than when it’s stopped. I guess I just never thought much about it really. I kinda just assumed that the "ram air" these things claim or just the air being forced up from the air dam into the intake to the throttle body at a higher rate caused this. I really don’t know if this is what exactly is going on but it kinda makes sense to me. Either way I don’t think there is a problem with it idling higher while the vehicle is at a high speed as long as it’s normal while you are stopped. As for it staying at the idle you rev it at for 15 sec, that I’m pretty sure is not normal. You may want to check all your vacuum lines and maybe clean your TB really good incase its sticking. Will it stay at high idle even when you are stopped until you turn the car off?

***SMWS6TA*** · 08-05-2011, 07:53 AM

OP, don't just replace the IAC, make sure you clean the TB out real good. Without a catch can you get a lot of oil in the TB and the ports for the IAC get gummed up pretty good.

**cammed goat** · 08-05-2011, 04:23 PM

When you cleaned your IAC, did you disconnect it from the harness? I can't be certain, but I think you have to do the relearn procedure for the IAC to work correctly after you re-install/connect it. Also, have you checked your throttle blade screws?

**Cutlass** · 08-05-2011, 06:17 PM

Don't get a bigger MAF. You don't need it.

5LTREATR · 08-06-2011, 11:15 PM

I borrowed a stock maf and problem is solved, Now the rpm's drop quickly down to 1100 for a few seconds then drop again to 800. However I only cleaned the air tunnel and blade of the TB while it was attached. I did unplug the IAC to clean it and wiped out the port that it mounts in there was not loads of crap in there but it was dirty, I checked to make sure the blade has freedom of movement and was not loosely mounted in there then did the idle relearn procedure seperately when I was done, I'll remove it take the sensors off and clean it up nice when I install a (stock replacement) Delphi MAF early next week. Also the Idle relearn procedure again. With the good MAF in there it is more responsive (Also more torque) and the transition from torque to horspower is smoother. Over the next few months I will talk to the Tuner and see what he recommends for headers and ask him if it necessary to go any further to get a HP increase keeping in mind that I don't want my MPG to drop drastically and put some time into strengthening the structure of the car. Thanks to you guys that put your 2 cents in!

**Lunatikgixxer** · 08-07-2011, 07:22 AM

my car does the same exact thing, like cutlass mentioned mine doesnt return to normal idle until i am completely stopped.. its really weird

**Cutlass** · 08-08-2011, 03:48 AM

Originally Posted by 5LTREATR

I borrowed a stock maf and problem is solved, Now the rpm's drop quickly down to 1100 for a few seconds then drop again to 800. However I only cleaned the air tunnel and blade of the TB while it was attached. I did unplug the IAC to clean it and wiped out the port that it mounts in there was not loads of crap in there but it was dirty, I checked to make sure the blade has freedom of movement and was not loosely mounted in there then did the idle relearn procedure seperately when I was done, I'll remove it take the sensors off and clean it up nice when I install a (stock replacement) Delphi MAF early next week. Also the Idle relearn procedure again. With the good MAF in there it is more responsive (Also more torque) and the transition from torque to horspower is smoother. Over the next few months I will talk to the Tuner and see what he recommends for headers and ask him if it necessary to go any further to get a HP increase keeping in mind that I don't want my MPG to drop drastically and put some time into strengthening the structure of the car. Thanks to you guys that put your 2 cents in!

Nice!