Idling Issues

[CTOESHO]

Well, it's getting colder out there here in Northern Illinois, and I can definetly see it though the SHO. I have been having idling issues every morning of the inital startup. The SHO will start and the tach will read around 2K rpm. Then it will slowly fall down to around 1500 rpm, until it skyrockets to 3K rpm and sits there for a few secs. At this time, I have Stage I mods except for UDPs, and you can definetly hear a difference from my 80mm MAF when it hits 3K rpms because it's a violent sucking sound. After my car warms up, and I hold the gas to 3K rpms, the sucks sounds has a different tone and sounds normal. After the car finally idles fine when I drive on the road, sometimes the same symptom will occur when I'm actually drviing! This means my car will all of a sudden pull to 3K rpm in whatever gear it is in. Obviously this speeds me up because I hang around the 2K rpm range when driving in town. I have to put the SHO in Neutral so I don't rearend someone. After about 10 seconds, the idle will then drop back to it's normal range. I already replaced my TPS and I ran my codes and the only thing that came up was that I had my LPM installed. Also, while it's at 3K rpms at the inital startup, sometimes the motor will all of a sudden just die. Most of the time it will drop down and the needle will bounce and then die, but I have noticed that it will just fall from 3K rpms because the motor killed itself. I currently just rolled 205K miles on my SHO and it has had a 60K done. Thanks in advance for any input.

<small>[ October 28, 2002, 12:07 PM: Message edited by: CTOESHO ]</small>

 

[twr]

Sounds like the AIB needs some cleaning.

 

[sdpatt]

There could be an invalid signal from the throttle position sensor that could be telling the idle air control valve to open. You may want to check the function of the TPS in relation to this problem.

 

[CTOESHO]

Well, I remember one time when the engine jumped to 3,000 rpm, I ran and opened the hood and felt to see if the butterfly was open on the TB and it wasn't. So does that rule the TPS out? Thanks.

 

[AutoSHO]

CTOESHO:
Well, I remember one time when the engine jumped to 3,000 rpm, I ran and opened the hood and felt to see if the butterfly was open on the TB and it wasn't. So does that rule the TPS out? Thanks.

Also, you might check to make sure the LPM hasnt worked its way off the computyer just a little bit. Another thing you could try is resetting the idle (disconnecting the battery). Good Luck!

 

[CTOESHO]

Well gang, here is the update. I installed a new TPS, and I cleaned the IAB just last night. The IAB was pretty gross, but not bad. I cleaned it with carb cleaner and q-tips. After reinstalling the IAB, the first start up was fine. There was erratic idle, and the engine did not stall. However, later that night when I started the SHO again, the idle again jumped to 2000 rpms after it had been idling at 1000 rpms. I think my SHO is possessed. However, I was just thinking that whenever my SHO does jump to 2-3K rpms after idling fine on the initial start of the day, the MAF sensor makes a different sound then if I were to manually hold the throttle at 2-3K rpms after the engine has warmed up. Could my 80mm MAF sensor be damaged or out of wack? The LPM by the way is still securely in the ECU. Thanks.

Mike

 

[sdpatt]

The intake sound is different if the air is passing through the IAC valve or the throttle plate. You probably need a new IAC valve.

 

[CTOESHO]

Thanks for the input Scott. Does the IAC come separately from the IAB? Or do I have to buy both the IAC with the IAB? Thanks.

 

[projectSHO89]

Mike,

The terms IAB and IAC refer to the same part. It's about 55 bucks from AutoZone.

Steve

 

[CTOESHO]

Sorry, I was thinking of the ISC which is the module that is attached to the IAB by the two screws.

 

[projectSHO89]

Same thing. It all comes in the same box, already assembled.

Steve