throttle body issues, need help!

[Mr. Bueno]

well another TB thread....

the rpms hang when the engine revs due to a new tb install. takes about 5sec for the rpms to drop down to the normal 700rpms or so. (the newly installed tb is a Mac 75mm attached to a CL plenum)

I checked the voltage of the tps and it is perfect. .98-1volt w/the throttle closed and about 4volts w/the throttle open. So I know the TPS is working properly. The idle speed screw is turned in all the way, and I get my desired 700rpms at idle.

why does the throttle hang, any suggestions would be appreciated. btw the IAC worked flawlessly, right up until I installed the throttle body
thx
tim

[Ponyperformance6]

Its not hanging, if it were hanging it would HANG,ie. not fall down at all. Sounds to me like you put a 75mm TB on a stock 4.6 for no good reason and it doesn't know how to act. Thats probably why it is recommended not to go larger than 70mm on a non forced induction 4.6. Its not necesary, won't gain you anything, and my guess is that its messing up your RPMs by maybe trying to take in more air than it needs.

[TheSean]

if you have an MAF the TB shoudnt mess with anything. check for leaks and loose connectors/vac lines.

[jdmoore144]

mine does it too. on the 02-04 they say put a 75mm throttle body and an 85mm MAF. i dont know y but it is different the the 99-01

[Mr. Bueno]

the 70mm and 75mm is recommended when used with the C&L intake plenum will. the 75mm also produces better hp/tq numbers when used with the plenum than that of a stock 65mm and 70mm tb.

a tb wont allow anymore air into the engine than what the engine demands.

sean i did check for vac leaks and lines and such. I will retorque the tb bolts a tad more just to see if that is a problem.

anyone else have suggestions? Horsepower, got ideas, i know you know tb's well

tim

[HORSEpower]

Probably the engine is holding the IAC open a little longer that's all. I wouldn't worry about it. Mine does that a little too.

Kurt

[Ponyperformance6]

the 70mm and 75mm is recommended when used with the C&L intake plenum will. the 75mm also produces better hp/tq numbers when used with the plenum than that of a stock 65mm and 70mm tb.

a tb wont allow anymore air into the engine than what the engine demands.

sean i did check for vac leaks and lines and such. I will retorque the tb bolts a tad more just to see if that is a problem.

anyone else have suggestions? Horsepower, got ideas, i know you know tb's well

tim


70 or 75.... I know, but the 75 is still too much and doesnt even really help compared to the 70. Anyways, It sounds normal to me, after all other people are reporting it. If you really want to know put the stock piece back on and then see what happens. Then you will know, and I guess just deal with it.

[Mr. Bueno]

70 or 75.... I know, but the 75 is still too much and doesnt even really help compared to the 70. Anyways, It sounds normal to me, after all other people are reporting it. If you really want to know put the stock piece back on and then see what happens. Then you will know, and I guess just deal with it.


well found out that mac help me fix it, nor could partshopper. I found out later that it is a bad casting by mac. IF you hold the TB up to the light you can see light coming through and around the TB blade and tb housing. This was allowing air to pass around the tb blade thus throwing the IAC outta wack with the throttle closed.

Partshopper was awesome, and sent me a new tb w/out charging me, and also sent me a shipping label to send back the crappy mac 75mm. I can say the new one is working fine, like it normally should. THe computer couldnt even adjust with the shitty 75mm, so thankfully this one works.

If anyone needs help tuning or adjusting aftermarket throttle bodies, jsut ask me, I spent many days fucking with this piece of shit.

I am glad it is working normally, since sporadic idles and rpm hangings are not normal :banghead:

TIM

[HORSEpower]

I found out later that it is a bad casting by mac.

TIM

Big Surprise there.

Kurt