Idle RPM Increase ?how to

[JCR]

Is there anyway you can increase the idle upwards about 25rpm's?. Can this parameter be changed without changing anything else. Can the Tech II do this ?. When I increase my idle the belt rumble disappears. I have the new alternator and tensioner. The slight increase in the idle seems to remedy this rumble /vibration Appreciate your feedback

 

[c4c5specialist]

Hi there,
I was wondering if you also received the latest calibration update from GM for your car.
While adding the tensioner, and the alternator will help, sometimes it does not repair the entire condition.
I would suggest that you check your program within the cars PCM, and see what calibration number you have.
Then, check with your local dealership and see if it needs to be updated, as I think you will need a reprogram.
No, there is NO way to raise idle speed manually with a Tech 2, and have it stay.
Allthebest, c4c5

 

[JCR]

Thank you very much for your reply. What you say makes a lot of sense. Just a tweak of the idle remedies this issue. Is it possible for me (myself) to obtain the calibration number ?. Can this be determined through the DIC ?. or is this strictly a dealer issue. I know there was an update done to the car in 1999 , but do not know if this is the latest one . It was supposed to increase the idle. My year is 98 and hate to go to the dealer and pay for something that is already there. Is it possible for the PCM to revert back to the original program?. Is this something that has to be redone peridically. Much appreciate your help. Thanks JCR

 

[c4c5specialist]

Hi there,
Honestly, if you have not had the car check in a year, 90% certain that you need a calibration update.
I recommend that 94 and newer Corvette owners check at least once a year for updates to the programs in the PCM. Program updates occur for many reasons. Fuel formulations, EPA, refinements in optimal operation of the engine, transmission and other things are all part of programming updates.
It takes about an hour to correctly program c5, as there is a special tool needed to isolate the PCM when programming. If it is NOT done correctly, there could be massive problems afterwards.
No, the PCM will never revert to another program, as it is rewritten over the old one when it is installed.
Another thing you must consider is mods on your car, do you have any which would change optimal air flow into your engine????
Other than that, the dealership can print out the calibration number that you have now, and the one that they will download to the car.
Allthebest, c4c5

 

[JCR]

Thanks once again, Only mod I have is a K&N air filter. I guess I'll schedule an appt. for this reprogram. The low idle is definitely abnormal and needs attention. Much appreciation .. JCR