Decided to work on the throttlebody on my '03. Pulled it off and noticed a weird looking raised area on the bottom in front of the plate and on the top behind it. So to aid airflow, I removed them. BIG F*ckin' mistake! Even though the plate can close completely, the ecm moves it to 20% @ startup. When it starts, it idles high, then "reduced Engine Power" shows on the DIC and the accelerator quits working. A DTC sets-"TPS to engine speed incorrect" or something like that. Can I adjust where the ecm positions the throttle w/ls1edit so its closed more @ startup? Looks like Tom just sold me a BBK 80 mm. Only a $400 f/up.

 

are you sure you didn't do something else? that little ridge in front is the main thing most people do when porting their own tb...myself included.

 

I have a stock TB I will sell you......PM me

 

I removed the metal under the blade where it rests w/the truck off. That's where I screwed up. Even though it can close tight, the comp opens it to where i removed the metal, leaving a large air gap top/bottom. If I had removed only to where it rests normally, I would be alright.

It has given me an opporunity to drive my old Turbo Regal, though.....

 

I LOVE those cars!! BTW the TB I have is off of an 03 and it is DBW.

 

Been there, done that. I didn't get reduced power mode, but it revvs to 2500 at startup, and had major cruise control at any speed. But throttle response was amazing.

I haven't finished tuning it up yet, but its definitely driveable and runs fine.

In LS1 edit:

You need to lower your RESET IAC PARK position from 310 down to about 200.
On the IAC park position, lower the values by 10-15%.
On the Idle Air table (running airflow), 10-15% lower values.
Then Airflow decay in Gear table, lower the values by say 10%.

Then test. This much should make it driveable. If not, I have an extra 03 TB.

Do some searching in the PCM tuning forum. Focus on vette tunes, as they have a similar fly-by-wire system.

 

Matt, the 03 TB is physically differnet. It has an aluminum growth on the bottom that resembles a tongue sticking out of the TB mouth. Its pretty thick. I'm sure that its there to direct airflow at very low throttle positions. I completely removed my TBs tongue, but didn't touch the blade seal at all. When it starts up, it feels like its got an air leak. Thats because the TB blade doesn't close all the way on an 03. There is no hole in the tb. When the computer calculates our IACs, it just opens up the TB a little instead. So by removing that flow hinderance, it gets more air in at 5% TPS than before. So it feels like an air leak, when its just getting more flow. You have to tell the PCM than it doesn't need that much air to idle and drive.

 

so, doing so on a TB on a non-dbw truck would automatically cause it to let in more air than it was supposed to correct, but on a DBW motor that only effects it until you change program? i'll have to yank the tube of the Yukon tomorrow and look at the TB.

 

With the manual TB, that spring keeps the TB closed up tight at idle. Then the IAC and the air hole allow enough air in to idle. With the DBW TB, the blade doesn't close all the way up. It adjusts itself open just enough to maintain a smooth idle, no air hole. By porting the TB, it really throws off airflow and thestock PCM program makes the TB let in too much air. It does adjust, but its slow.

 

interesting...i'll remember that because i was thinking about porting on the TB on the yukon this week during some down time with school (all night classes this semester)...hmmmm