so tonight after my straight pipe install , i decided to port and polish my throttle body. Ya i know i dont know what i'm doing and someone will chime in with that, but i spent a few weeks reading up on it and worst case scenario, i buy an after market. I wasnt too extreme, just took a bit outta the mouth of it and polished it to a mirror finish. I also "knife edged" the butterfly. during this time i had my battery disconnected (3-4 hours). I reinstalled, fired it up and let it idle to operating temp. idle was smooth at 800rpm or so. took off, kicked on defrost (A/C) and the idle hopped up to 2k and stayed there. shut off the A/C and it still stayed. drove around awhile and it dropped down to 800rpm again every time i let it idle without the AC on. but AC on....and it would jump to 2k. I hit the freeway for a few, got off, and the idle now was at 1500rpms wether the AC was on or off. drove my 50 miles home, got off the freeway and it SEEMS to be all normal idle now (800 rpm) with the AC on or off. any ideas? did i mess up and port too much? or does the computer need to relearn. is there an idle relearn process? hmmm. thanks


EDIT: so i thought to use the search feature and its amazing...i found what i was looking for. appears either i somehow messed up the butterfly seal by going to far in ( almost SURE i didnt ) or i just need to try the idle relearn feature. i'll give it a shot in the morning. thanks in advance.

 

If you got too far down in near the blade that will do what you are describing. Since the C5 doesn't have an IAC like the fbodys you have to be really careful when getting near that ridge in front of the blade. That ridge controls the idle. Another thing is that it seems that I personally have had trouble when I knife edge the blades. I do alot of throttle body porting and sell online but I won't do the knife edge anymore. Now a tuner can correct all you problems with some tweaking of the idle tables but most people don't want to do that just from porting a throttle body.

 

Hmmmm....that's unusual. Usually the DIY throttle body porting works perfect.

 

You might look for other things too like a serious vacuum leak.

 

Knife edge killed ya.No hp in it,just aggrivation like you have.

 

Lucky...ya know I was thinking the exact same thing! I was totally shocked. Anyhow...I did the idle relearn dealeo today and so far (fingers crossed) it worked...no problems all day. The seat of the pants meter says the throttle is more responsive and it might have a little more kick on the top end. Who knows, it was free and I learned alot. Thanks for the replies.

 

idle problems happen regularly with ported TB's if not done properly.

 

and retuning after the porting

 

can u tell me how to doo it thanks

 

Sounds as though you may have problems with your porting job, but, try this:

The car will re-learn simply by driving it between 50-100 miles. Or, the actual way to do it more quickly, is the following procedure:

1) Insert key into ignition and turn to the “ON” position, but, DO NOT START THE ENGINE.
2) Open the engine compartment fuse box cover and remove the two 10 amp fuses from position numbers 16 & 23.
a) According to the manual there are two fuse boxes. Use the engine compartment fuse block for this procedure not the instrument panel fuse block.
b) Engine Compartment Fuse Block (correct one): 16 is Powertrain Control Module A and 23 is Powertrain Control Module B.
c) Instrument panel fuse block (wrong one): 16 is Air Bag, 22 is Body Control Module-Ignition and 23 is Body Control Module-Ignition 2.
NOTE: Your DIC will now display “check” messages for ABS, etc… Do not worry as this is normal.
3) Turn the ignition key to the “OFF” position.
4) Return to the engine compartment fuse box and re-insert both 10 amp fuses for positions 16 & 23.

5a) Idle relearn for an M6:
1) Start the engine and allow the coolant temp to reach a minimum of 176 degrees F. Allow the engine to run at this minimum temperature for at least 5 minutes.
2) After the 176 degree, 5 minute minimum run, shut down the engine for a minimum of 30 seconds.
3) Restart the engine and check for DIC error codes (there should be none).
5b) Idle relearn for an A4: (different)
1) Start the engine and allow the coolant temp to reach a minimum of 176 degrees F. Allow the engine to run at this minimum temperature for at least 5 minutes.
2) Allow the car to idle in DRIVE, with air ON and then OFF, for 5 minutes each, and then in NEUTRAL, with air ON and then OFF, for 5 minutes each.
3) Turn the car off for at least 30 seconds.
4) Restart the engine and check for DIC error codes (there should be none).
6) Drive car for a minimum of 30 miles at varying rpm settings and speeds. PCM will now re-learn and adjust for the new air flow and temperature at the intake.
a) If error codes persist, repeat steps 1-7. Make sure fuses are properly inserted before repeating steps.
b) Do not deviate from the sequence outlined above. If you do, restart the sequence from scratch.
c) Steps 1-4 are also necessary if you ever disconnect your battery or lose power for any reason.
Ed