2.4L Alero Fast Idle / dan_f/bnaylor/2000oldsalero

[killiange]

I am having a fast idle problem w/ my '01 GL 2.4L. Idles to 2,500 on startup then settles at ~1,500 RPM. I have seen this issue tracked in another thread by dan_f, bnaylor, and 2000oldsalero that thread was closed and seems never reopened before the item was resolved.

Did you guys or anyone else ever figure out a solution to the problem? I've replaced the parts as discussed in the thread, and still no fix.

Thanks!!!
Greg

[Salestax]

I'm new so I dont know what parts those were. I would first tell you to check for vacuum leaks, but I dont see where that would allow the idle to drop after the cold start.
Next suggestion would be remove and clean the ISC/IAC motor as well as its bore.

[BNaylor]

Originally Posted by killiange

I am having a fast idle problem w/ my '01 GL 2.4L. Idles to 2,500 on startup then settles at ~1,500 RPM. I have seen this issue tracked in another thread by dan_f, bnaylor, and 2000oldsalero that thread was closed and seems never reopened before the item was resolved.

Did you guys or anyone else ever figure out a solution to the problem? I've replaced the parts as discussed in the thread, and still no fix.

Thanks!!!
Greg

What thread are you referring to? There are two Moderators that handle every Oldsmobile subforum on AF. That's me and GTP Dad. Part of our job is to make sure members comply with AF Community Guidelines. The thread was probably closed because it was too old. It is against AF rules to resurrect old threads. Therefore, it was probably closed for that reason. However, closed threads can still be viewed for historical and reference purposes.

Now if you have a problem with your Alero then it is better to start a new post. The other option is to PM the member and ask he/she what resolved their issue.

Since this is your new thread I would highly recommend listing what parts have been replaced or what attempts at corrective action you have taken to date so everyone will be on the same sheet of music and be able to help you out.

BTW - Welcome to AF.

[killiange]

Thanks for your help so far...

The earlier thread I was referring to is at: http://www.automotiveforums.com/t489...dy_tried_.html, and it looked like it was closed down b/c it was too old.

Anyhow, I have replaced the IAC, cleaned out all bores in the TB thoroughly, replaced both O2 sensors, and checked all vacuum lines that lead to/from the TB. Replaced one line that was a little cracked. Others seem fine.

This may sound strange, but the idle tends to consistently be 200-300RPM higher (settles to 1700-1800) after the car sits overnight. Later in the day, the idle rests at ~1500 as discussed in orig post. Strange, I know, however it is consistent and repeatable, so maybe worth consideration. Could also be outside air temp related as it is cooler in the am??

Thanks!!
Greg

'01 Alero 2.4L/5-Sp, '65 Beetle

[GTP Dad]

Check the area around the throttle body and the IAC. It is possible that there is a vacuum leak there and you can't detect it. If you have checked all the hoses then check the power brake booster. Sometimes the check valve on the vacuum line will leak. These are the three areas that I can think of that may be causing the issue. The only other thing would be a bad throttle position sensor that may be giving incorrect signals to the ecm.

[BNaylor]

All I can recommend is try the following:

Disconnect the battery negative for a short period of time. Then reconnect. Turn key on for at least 5 seconds then off for 10 seconds. Then start and see what it does.

If that doesn't work then you may have PCM module problems. I recall that is common on GM "J" and "N" body cars with the 2.4L. You could check with a GM dealer to see if there is a software/firmware revision out on your year and model Alero for the PCM. Maybe a reflash will help, otherwise you may be looking at replacing the PCM.

In my experiences most of the time a bad engine vacuum leak will cause a rough idle and the idle to decrease depending on where the possible leak is, if any, on the intake manifold and throttle body areas.

[killiange]

FIXED!!! The "reboot" of the PCM did the trick. Thanks for your help...this problem was driving me crazy!!

-Greg

'01 Alero GL2/2.4L/5-sp, '65 Beetle

[BNaylor]

Originally Posted by killiange

FIXED!!! The "reboot" of the PCM did the trick. Thanks for your help...this problem was driving me crazy!!

-Greg

'01 Alero GL2/2.4L/5-sp, '65 Beetle

Thanks for the feedback. Sometimes it is the simple things we have a tendency to overlook.

[Greg1290]

The pcm "reboot" fixed my 2.4 high idle also! Im so glad i seen this! I took the negative post off and took the iac valve off and sprayed intake and carb cleaner in the valve and sprayed the throttle body well and assembled everything back togther and left the negative post off for an hour or so and put it back on did the key on for the 5 seconds and back to off for 10 seconds then started it it wasnt idleing high at all for a cold start now all the cleaner spray that was still in the throttle body and the intake was up and down idle for just a min or so till it cleared that out but after that perfect was idleing way high on start up and would hold there for quite a while before working on it and the pcm reboot very satistfied now and extremely blessed to see this post. Thank you!