Rpm will not drop
Thread Starter
Instructor
Joined: Dec 2009
Posts: 236
Likes: 0
From: Houston Texas
Rpm will not drop
High I have a 1989 corvette and the other day I swaped the throttle body for a Professional Products 58mm TB, I did use the origtional bottom end (IAC) on it, and I have not had time to bore the intake. Anyways hooked it all up and now when I start it it will idle like it always has (around 900) and then when I give it gas it gets hung up more and more at higher rpms, it will do this till I work it all the way to 3 grande and then once past that I hit the gas all I want but it will just fall back down to 3 grand, in other words its stuck.
Do I need to reset somthing, I did have to take that throttle positioning sensor off to put it on the new throttle body as well as the IAC valve, and I did not exactly set it to anything proper that I know of, just bolted it on. Also I had to splice the boot (from Mass air flow sensor to the Throttle body) so it would fit around the throttle body and then Tap it shut with the hose clamp on it if that means anything.
Please, someone walk me through with a fix, I need to get it outa our street and in the garage and right now im scared to even start it yet alone drive it, Thank you guys so much!
Do I need to reset somthing, I did have to take that throttle positioning sensor off to put it on the new throttle body as well as the IAC valve, and I did not exactly set it to anything proper that I know of, just bolted it on. Also I had to splice the boot (from Mass air flow sensor to the Throttle body) so it would fit around the throttle body and then Tap it shut with the hose clamp on it if that means anything.
Please, someone walk me through with a fix, I need to get it outa our street and in the garage and right now im scared to even start it yet alone drive it, Thank you guys so much!
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
If you installed a 58 mm on a stock plenum then the actually throttle blades are probably stuck/binding in the plenum itself. Your going to want to remove the entire TB from the plenum and check the throttle blades for damage....if they are damaged then this will affect your idle once everything is installed/adjusted properly in the future.
This is a great opportunity to remove the IAC from the housing and clean everything througly before you reinstall it.
Port the plenum before you reinstall the oversized TB again.
Do some "searches" here on the forum to figure out how to do the following....these proceedures have been posted many many times in the past.
You'll need to set the TPS Voltage.
You'll need to reset the IAC.
Aftermarket TBs can be a bit of a hassle to install since you'll more than likely need to mess with the throttle stop screw to get it dialed in just right......but remember everytime you change the throttle stop's position you'll need to check or even reset the TPS voltage again.
This is a great opportunity to remove the IAC from the housing and clean everything througly before you reinstall it.
Port the plenum before you reinstall the oversized TB again.
Do some "searches" here on the forum to figure out how to do the following....these proceedures have been posted many many times in the past.
You'll need to set the TPS Voltage.
You'll need to reset the IAC.
Aftermarket TBs can be a bit of a hassle to install since you'll more than likely need to mess with the throttle stop screw to get it dialed in just right......but remember everytime you change the throttle stop's position you'll need to check or even reset the TPS voltage again.
Team Owner
Joined: Jan 2003
Posts: 20,275
Likes: 236
From: Summerland B.C. Canada
You need to set the minimum idle and TPS idle voltage. The IAC will reset itself, the next time the motor is started.
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Thread Starter
Instructor
Joined: Dec 2009
Posts: 236
Likes: 0
From: Houston Texas
If you installed a 58 mm on a stock plenum then the actually throttle blades are probably stuck/binding in the plenum itself. Your going to want to remove the entire TB from the plenum and check the throttle blades for damage....if they are damaged then this will affect your idle once everything is installed/adjusted properly in the future.
This is a great opportunity to remove the IAC from the housing and clean everything througly before you reinstall it.
Port the plenum before you reinstall the oversized TB again.
Do some "searches" here on the forum to figure out how to do the following....these proceedures have been posted many many times in the past.
You'll need to set the TPS Voltage.
You'll need to reset the IAC.
Aftermarket TBs can be a bit of a hassle to install since you'll more than likely need to mess with the throttle stop screw to get it dialed in just right......but remember everytime you change the throttle stop's position you'll need to check or even reset the TPS voltage again.
This is a great opportunity to remove the IAC from the housing and clean everything througly before you reinstall it.
Port the plenum before you reinstall the oversized TB again.
Do some "searches" here on the forum to figure out how to do the following....these proceedures have been posted many many times in the past.
You'll need to set the TPS Voltage.
You'll need to reset the IAC.
Aftermarket TBs can be a bit of a hassle to install since you'll more than likely need to mess with the throttle stop screw to get it dialed in just right......but remember everytime you change the throttle stop's position you'll need to check or even reset the TPS voltage again.
