75mm BBK throttle body problems

i just finished putting on a 75mm BBK throttle body (that i bought used), and have had some problems. first, the truck is a 98 sport with a 5L, and a m90 supercharger on it.
when i did the throttle body, i also make a bigger throttle body elbow as well (3 1/2 inch), and modded the shaft for the butterfly by cutting the part of the shaft that faces you when its closed. now that is on, here are the problems. this thing whistles and hums like mad. its already driving me nuts, and its only been a day, i am having some idle issues with it, and now have a P1506 code (Idle Air Control Over Speed Error),
at first i thought it was the IAC, and lucky for me, i had a bran new one kicking around. tried it, no luck. took the elbow off thinking that the flanges were warped (checked with a strait edge), and they are flat. anyone else have these problems at all?

 

[Turdle]

You might have the iac mounted backwards--rotate it 180 degrees and bolt it back on.

 

[vroomzoomboom]

correct me if i am wrong jon, but isnt the connector suppose to face the front of the truck? thats the way i have it now, and i think that the way the one that came with it was facing.

 

[Turdle]

Yeah, but if it is on backwards it will rev high and whistle.

It can't hurt to try--I might be wrong, but it's worth a shot.

 

[Dono]

Tim, I hate to say I told you so....but I told you so.

The iac can go one backwards, and I made that mistake on my 4.0 ohv build also.

Now, once you are certain the iac is on the right way, there is an adjustment procedure for your new throttle body to get idling correct.

You should be able to unplug your iac with the motor warm and have the idle drop maybe 100-200rpm. To accomplish this, you need to adjust the bbk butterfly with that screw so that the right amount of air gets thru.

I had this problem with my accufab. It had tighter tolerances than my factory throttle body and my cold starts were really crappy and I couldn't get a higher idle. I was on James thinking it was part of the tune. He'd make adjustments with no change. I then followed StreetRod's iac adjustment procedure and suddenly my cold idle was great and everything came in to line for me.

So,
step 1...make sure iac is on the correct way.
Step 2, adjust butterfly on BBK so your truck warm idles a little low with iac unplugged.

Your close Tim. I have a feeling many of us have lived your pain. I know I have. I'm happy to swing by and see if I can help. Sometimes 2 heads can make something like this go away fairly quickly.

 

[vroomzoomboom]

jon, go fish. tried putting it on 180 from what i had it mounted as, and it idled normal, till i blipped it, then it snapped up to 2,000 and whistled worst.
don, i had i feeling if you saw this thread, you'd be saying that
so i did call bbk and ask them wth? what that told me was the whistle i have may be because i have a sharp edge some place. well, i cant argue there, there is a step up from the elbow i made to the explorer express intake. so one day (not today or tomorrow either) i will have to ramp it somehow, and pray i dont screw that up. the idle, i did ask them if there was a way i could adjust it, and like you said don, they told me i could adjust that screw. so i will try that a little later when it cools off.....if it cools off up here.

 

[Dono]

Yup, it's too hot for the garage. That's for sure.

I have dremmel bits you can use to smooth the edges Tim. Even an air compressor and die grinder if you want. The bits are perfect for what you need to do, and will make short work of those edges.

Edit...sounds like you had your iac on correctly the first time afterall. Your lucky.

 

[vroomzoomboom]

Edit...sounds like you had your iac on correctly the first time afterall. Your lucky.

there is no luck in being good. (now watch, just because of that remark, nobody will chime in after it )

as for the dremel stuff, have that covered. i dont think i will do that for a while. i was also going to turn down the screw for the butterfly, until i realized, we have to mount these upside down, and the screw head is facing the valve cover. looks like that wont get done either till its cooler out as well.
this was a productive day....

 

[vroomzoomboom]

huh. amazing what a google search will find

whistle fix

http://www.allfordmustangs.com/foru...rottle-body-whine-high-pitched-noise-fix.html

 

[Dono]

I always forget Google is our friend. Makes perfect sense. The idle adjust sounds like it will be a pita.

 

[vroomzoomboom]

dont think it will be to bad. just have to flip it over, and run it without a throttle cable. i will try it tomorrow if its not as hot as jamaica

 

[vroomzoomboom]

so i have been screwing around with this thing for the last few days. i did the die grind trick to it, but, the whistle is still there. now, i have zero volts at the TPS, and it shifts like hell. this thing is really starting to piss me off, and i wanted to go to the track on saturday......grrrr

 

[Dono]

Never give up!
I'm sure the real issue is trying to work in the heat.
We are just not used to this killer heat and humidity up here.

Just wait.......another month and ill be whining that my hands are too cold to feel the tools as I'm trying to work on my truck. And I'm not even kidding.

What ever happened a nice even temperature?

 

[R1dd1cK]

Well here is my experience with BBK throttle bodies. I used to have 75mm BBK on my tibird untill I put the 85mm that it has on it now. The problem I had was there is orings around the shaft that will go bad and leak and squawk. Might be worth looking at.

 

[vroomzoomboom]

so here's how things went.
i went home and pulled the TPS off and checked the voltage. with it in my hand and turning it with a screw driver, it would sweep the volts. then when i put it on the throttle body, dead. take it off, and if i snapped it open, and closed, dead as well. so the problem is with the TPS. lucky for me, the donor 97 5L motor i have has the same TPS as the bbk one (the 98 TPS is different).
while at work to i went on bbk's site (did i mention that we are not suppose to do stuff like that at work......ever) and found a instruction manual PDF. it showed the way to adjust them.
first, the tell you for idle, to turn the throttle stop 5 turns after in makes contact with the screw. so i did that, then they tell you to start the car up, and set your idle.
i am going to go out on a limb here and say, i am sure my neighbors really didnt like evil screaming at 3000rpms in my driveway.....nether did i. so i got it set. then they tell you to check the TPS voltage. it should be between .80 an 1 volt. well, i am close, i got it to 1.01 volts when it should be at idle, and 4 volts at WOT.
i took it for a drive and.....this throttle body sucks. if i stood on it with the stocker, it would light the tires to second gear, this one, maybe 3/4 in first. so i have lost bottom end. also, as for the whistle fix, yea, that work, its louder now. great. well, at least its running and shifting again. i think i might run out to one of my parts trucks and grab a TPS for my stock throttle body, and try it out and see if there is a difference.

 

[Dono]

Oh, man. Its funny how things that should be so simple never are. HaHa.....sic.
Ah, the modification game.

 

[Jakee]

Is there a little plastic round like spacer on the face of the TPS that meets the TB mounting surface? I had an issue (it's been along time since I installed mine) and found that I had to remove this pc. in order for the end shaft to engage the actual TPS.

 

[vroomzoomboom]

its funny you say that, because i found that laying on my bench, and not sure how long it has been there
so i wanted to make sure it was the throttle body that was giving me problems, and had nothing to do with the elbow i made, and pulled the bbk of, and put the stocker back on (and also modified the butterfly shaft on it as well). i have .99v when the throttle is closed, and 4.66v when open. no idle issues, no check engine light, and no whistling either. it also moves out like it should, shifts harder, and pulls. the only thing i happen to notice was the bbk return spring is stiff, because just holding it in my hand takes a little force before it goes to wot.
so for now, its staying off, and i will play around with it a little more another day. i want to get to the track tomorrow. i was going to bring both with me, make a few runs, and change them, but going by the seat of the pants dyno, the stocker is way better at this point.

 

[GRNMACHINE]

sorry you havin so many probs after all the work on the BBK, good thing you got things pinned down again with the stocker. We are all going to need to see some vid's, Cant get enuff of Evil!!!

 

[Jakee]

Glad you got it figured out.
If you try the BBK again, you can release tension on the spring. Like you, I don't like there to be more tension than needed, so I did this with a 70MM BBK.