New TB Stuck RPM
08-18-2010, 11:33 AM
#1
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
New TB Stuck RPM Got a 52mm ported TB for my car today.. Came with a slightly old IAC..
When I rev it, it gets stuck at about 2k rpms sometimes, and i have to tap the gas pedal to get it down.. In gear it's about 800rpms, and with AC about 640rpm..
Wtf? The datalogs show zero IAC steps at idle with air or not.. When I rev it it sometimes climbs a little in IAC steps to like 3..
Faulty IAC?
When I rev it, it gets stuck at about 2k rpms sometimes, and i have to tap the gas pedal to get it down.. In gear it's about 800rpms, and with AC about 640rpm..
Wtf? The datalogs show zero IAC steps at idle with air or not.. When I rev it it sometimes climbs a little in IAC steps to like 3..
Faulty IAC?
08-18-2010, 12:17 PM
#3
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
The TB came with the TPS already on, so I figured it was already adjusted.
At closed, it reads .58.. though if i lightly rev it and let it drop back down slowly, it goes to .60, I actually have to close the blades myself, they don't close all the way on it's own.. Now get this, if the engine is OFF, they close perfectly by themselves, like butter...
At WOT, the PCM only reads to 84%, never 100.. So it never even reaches power enrich it looks like, because if i floor it, it'll upshift WAY to early..
If this TB is faulty, im gonna be pissed..
At closed, it reads .58.. though if i lightly rev it and let it drop back down slowly, it goes to .60, I actually have to close the blades myself, they don't close all the way on it's own.. Now get this, if the engine is OFF, they close perfectly by themselves, like butter...
At WOT, the PCM only reads to 84%, never 100.. So it never even reaches power enrich it looks like, because if i floor it, it'll upshift WAY to early..
If this TB is faulty, im gonna be pissed..
08-18-2010, 12:50 PM
#5
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
4.11v...
Here's the video of it getting stuck at the idle area though, ONLY when the engine is running though..
http://www.youtube.com/watch?v=Lv7P7q8j3es
Here's the video of it getting stuck at the idle area though, ONLY when the engine is running though..
http://www.youtube.com/watch?v=Lv7P7q8j3es
08-18-2010, 01:39 PM
#7
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
It is so clean it's nearly like a mirror inside..
Thing is, even when closed all the way, it doesn't idle right.. i might close off the idle bleed hole, and force ALL idle air to go through the IAC, cause it's bleeding through the blades..
Thing is, even when closed all the way, it doesn't idle right.. i might close off the idle bleed hole, and force ALL idle air to go through the IAC, cause it's bleeding through the blades..
Trending Topics
08-18-2010, 02:16 PM
#8
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
08-18-2010, 04:22 PM
#9
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
Ok I purchased a new IAC.. $50 at Autozone.. At first they said they didn't have it, I told them it showed it in stock online, and the guy at the counter didn't do anything to show he cared or try and find out why it showed they not having it..
All other stores wanted like $129 for the part..
I go back to autozone website, place order for store pickup, shows ready. They DO have it, and the manager gave me the part, and I told him all about how I was told they did not have it, but in a happy mood (cause i was happy, that i finally got the part).
It won't fix the sticking, but hopefully it fixes the crazy high idle..
All other stores wanted like $129 for the part..
I go back to autozone website, place order for store pickup, shows ready. They DO have it, and the manager gave me the part, and I told him all about how I was told they did not have it, but in a happy mood (cause i was happy, that i finally got the part).
It won't fix the sticking, but hopefully it fixes the crazy high idle..
08-18-2010, 06:44 PM
#12
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
http://www.youtube.com/watch?v=TbbNWumrd58
I made that video yesterday when I was planning to install it.
08-19-2010, 11:09 AM
#15
Staging Lane
iTrader: (3)
Join Date: Aug 2006
Location: red oak, texas
Posts: 85
Likes: 0
Received 0 Likes
on
0 Posts
If they close like butter when the engine is off but hang open when the engine is running it sounds like it's not able to close due to engine vacuum. I think I've read some of the aftermarket tb's run into this. The return spring needs to be stronger.
Also, your right, close off the iac bypass to make all the idle air go thru the iac. Hopefully that will allow the iac to have control over the idle.
Also, your right, close off the iac bypass to make all the idle air go thru the iac. Hopefully that will allow the iac to have control over the idle.
Last edited by quicksilver383; 08-19-2010 at 11:30 AM.
08-19-2010, 12:44 PM
#16
You said the TB was ported. Who ported the TB? It almost sounds like you need to check the blades and the bore for a binding point. you can use a sharpie to color around the bore where the TB blades meet the bore. If you open and close it several times you should be able to see if there is a binding point for the blades. Like the guy above said you may have a weak return spring or the shaft it's self may be binding. Checking the wear marks with a sharpie can be done fairly quick before you have to take it apart. I always question the work when I don't do it.
08-19-2010, 01:38 PM
#18
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
You said the TB was ported. Who ported the TB? It almost sounds like you need to check the blades and the bore for a binding point. you can use a sharpie to color around the bore where the TB blades meet the bore. If you open and close it several times you should be able to see if there is a binding point for the blades. Like the guy above said you may have a weak return spring or the shaft it's self may be binding. Checking the wear marks with a sharpie can be done fairly quick before you have to take it apart. I always question the work when I don't do it.
08-19-2010, 02:55 PM
#19
Teching In
Thread Starter
Join Date: Aug 2010
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
There is no binding.. I did a sharpie, and no marks are ever left on it.. I think it's just a weak spring and the need for a IAC bleed hole block off..
So...once again, how do i remove the spring?
So...once again, how do i remove the spring?
08-19-2010, 09:04 PM
#20
I can tell you from looking at the throttle body in the video that you have the wrong throttle body for your application, that is unless you have swapped a 92/93 LT1 into your car. The throttle body you have is is for a 92/93 LT1, it has the TV kick down cable hook-up for the 700R4. I would compare the throttle body you removed from your and and this one and I think you will see the difference in the units.
I have been porting throttle bodies for the past 9 years and have had a few guys pick up a used one for me to port, not realizing that it was a 93. They send it to me, I do my work and they have idle issues when they install it. After about a dozen emails and scratching our heads we would come to find out it was the incorrect throttle body for their application. I'm sure you could make it work but I haven't tried first hand so I cannot tell you what you need to do to make a 93 throttle body work on a 94-97 car.
There are a few small differences between the 92-93 and the 94-97 throttle bodies. First the throttle cable hook-up and linkage is different. Second is the throttle blades sit at much more of an angle when closed than the 94-97 units do. The blades in 94-97 unit sit nearly perpendicular to the throttle bores, only about a 6 degree angle, the 93 unit is much more than 6 degrees. So with a 93 unit there is less rotational travel in degrees from closed throttle to WOT. This and the fact that the linkage is different can cause idle issues that are hard to fix. I also believe that the TPS sensor is different on the 92-93 throttle bodies as well.
I'm sure you probably don't want to hear it but I would sell that throttle body and get a 94-97 one. If you picked it up for $70 you should be able to get your money back out of it pretty easily.
I have been porting throttle bodies for the past 9 years and have had a few guys pick up a used one for me to port, not realizing that it was a 93. They send it to me, I do my work and they have idle issues when they install it. After about a dozen emails and scratching our heads we would come to find out it was the incorrect throttle body for their application. I'm sure you could make it work but I haven't tried first hand so I cannot tell you what you need to do to make a 93 throttle body work on a 94-97 car.
There are a few small differences between the 92-93 and the 94-97 throttle bodies. First the throttle cable hook-up and linkage is different. Second is the throttle blades sit at much more of an angle when closed than the 94-97 units do. The blades in 94-97 unit sit nearly perpendicular to the throttle bores, only about a 6 degree angle, the 93 unit is much more than 6 degrees. So with a 93 unit there is less rotational travel in degrees from closed throttle to WOT. This and the fact that the linkage is different can cause idle issues that are hard to fix. I also believe that the TPS sensor is different on the 92-93 throttle bodies as well.
I'm sure you probably don't want to hear it but I would sell that throttle body and get a 94-97 one. If you picked it up for $70 you should be able to get your money back out of it pretty easily.