Car Idles weird after Ported TB install

pheer · 10-11-2009, 10:16 PM

i have a 2002 Trans Am
i installed a ported throttle body from a 98-99, i've heard the TBs are slightly different, the cable lobe and cam are diff or w/e
the cable wouldnt tighten enough when i first installed it, so, i swapped what i am assuming is called, the cam and lobe.... the bar through the middle and the plate holding the cable....
the car starts fine but idles high at times. if i merely let off the brake in while in Drive, the car almost accelerates by tiself... i have hit close to 40mph and never hit the accelerator.... i have check the cable tension and let it loose to no effect....
this ony happened after the TB install
the new TB has been ported, epoxied and has the bumpstop mod...

anyone know why something like this would be happening

nick1ta · 10-11-2009, 10:34 PM

Check to see if the TB is closing completely. If not, it will allow air to enter the motor and therefor the computer will tell it to add fuel. It will act if you had your foot on the gas!
A good way to check is to take the TB off the car and while closed hold it up to a light and see if light is coming through the blade anywhere. If it is then you can loosen the blade by the two screws and shimmy it until it sits right.

LSXDoc · 10-11-2009, 10:39 PM

sounds like a bad vacuum leak

pheer · 10-11-2009, 10:45 PM

i've heard vacuum leak several times in other places... but this is only after the TB install.... is tehre a safe, easy way to check if it is in fact a leak?
i'm definitely going to check the TB tomorrow as well...

LSXDoc · 10-12-2009, 12:34 AM

nick1ta is correct for checking the TB for internal leaks, but for external the easy way is cigarette smoke blown casually around the TB and intake. if any looks like it is sucked in, then you have a vacuum leak there.

pheer · 10-12-2009, 03:42 AM

so, assuming it is a leak, somewhere.... how do i fix it? i realize the blade can be fixed seemingly easy.... what about the other?...

bene · 10-12-2009, 04:33 AM

Quote:

Originally Posted by pheer

so, assuming it is a leak, somewhere.... how do i fix it? i realize the blade can be fixed seemingly easy.... what about the other?...

Gotta find out where the leak is at first then diagnose to fix it, brotha'.

pheer · 10-13-2009, 02:17 AM

ok, so, i'm assuming it's the blade, because i blew smoke as suggested, and didnt see any being sucked in anywhere.... as far as moving the blade goes, isn't it held in place by two screws, so it can't really move at all?

LSXDoc · 10-13-2009, 03:00 AM

have you played with the adjustment screw for the blade?

pheer · 10-13-2009, 06:01 AM

i have yet to take the TB off as i havent had time yet...and,tehres an adjustment screw? all i knew about was the two that go through it to hold it in place...

RaggedRides · 10-13-2009, 08:51 AM

You tried some, but if you have some WD40 or carb cleaner laying around, spray it around the outside of the throttle body as the car's running. If it seeps in the revs will climb. Another place to check is to make sure the MAF is tightly secured to the TB and intake too.

pheer · 10-15-2009, 01:57 AM

ok so, i tightened some things up today, and found something out...
it only idles high and such, and acts like i'm pressing the gas (vacuum leak) when the AC is NOT on..... not sure if that changes anything, jus thought i'd add that....

billyb · 10-17-2009, 04:29 PM

proably ported too much, sucking too much air,you;ll have to take it off and look @ the blade,hopefully it wasn't sold to you because of that !!

jimmyblue · 10-17-2009, 05:00 PM

There's a stop-screw for the blade that you have to
get at from below, with an Allen wrench.

IAC channel could be fouled with the fill-epoxy and
not able to let the plunger seat properly, or do so
intermittently.

People do "oops" the porting sometimes and make
the seating circle gap from the blade. Blade has to
come out for porting (unless you're dumb) and may
have been reinstalled off-center. Loosen, let it snap
home and retighten for a best centering, with that
stop-screw backed out, and then turn the screw
in until the blade just barely does not bind under
vacuum.

People also overdrill the hole in the blade when they
are chasing too-low idle problems without the tools
to tune it right.

pheer · 10-17-2009, 05:05 PM

that was one thing i noticed about the blade on the newer one, the hole in the middle has indeed been drilled and is just a tiny bit bigger than my stock un-ported one... maybe i'll try changing out the blades, since the new one wasn't razored anyways...

pheer · 10-19-2009, 12:15 AM

well, i went back today and swapped in the old blade, seems to have fixed things, idle is normal and the car doesn't accelerate on its own anymore.... hopefully this is the end of that
im blaming the hole in the middle being drilled out too much...

pheer · 10-23-2009, 03:20 AM

sorry to... triple post here....

went to start the car today, about mid-day... turned it over and the RPMs went up to about 800, then dropped till it died... had to give it a bit of gas the next time to get it going smooth.... even after that, until the engine got up to temp, it would idle at 475-525.... any reason for this? i jus did an oil change, don't know if that would have something to do with it

hitmanws6 · 10-23-2009, 03:30 AM

Quote:

Originally Posted by pheer

sorry to... triple post here....

went to start the car today, about mid-day... turned it over and the RPMs went up to about 800, then dropped till it died... had to give it a bit of gas the next time to get it going smooth.... even after that, until the engine got up to temp, it would idle at 475-525.... any reason for this? i jus did an oil change, don't know if that would have something to do with it

that sounds like your IAC

pheer · 10-23-2009, 03:37 AM

assuming that's what it is.... any clue what's wrong with it? and how to fix it?

GMLSX · 10-23-2009, 12:09 PM

If the T/b isnt ported correctly it can leak extra air around the throttle blade. Katech performance sells a CNC ported one they work excellent!