High Idle with New Pro Products 75mm T-Body

barberben

Registered User
Ok guys, I'm back again with another issue. I finally had my new Professional Products 75mm throttle body installed. The car runs like a scalded dog, but when I crank it, it revs to about 2500, then idles at about 2000, then settles in at 1600 to 1700 after running for a few minutes. I have read EVERYTHING I could find about this issue, and about this particular t-body. I have narrowed it down to 2 probabilities. Most people that have had this problem have fixed it by replacing their IAC, but I have also read that some guys had to drill the Idle Adjustment screw down further on this particular throttle body.

If there are any of you that have done the "drilling down" process, how did you do it? do I need to take the TB back off or can I do it on the car?

Any ideas?

Barberben
 
It sounds like you have a vac leak somewhere. Check around the mating areas and close the bleed screw all the way. And adjust your stop screw down.

Did you install the TP sensor incorrectly that might be a problem too.
 
Make sure that the blade is closed all the way that you can get it. If it is getting alot of air past the blade, the IAC isnt working that much and you will have a high idle that slowly goes down. Like when you come to a stop and then the idle drops, at least thats how i fixed the high idle issues I had with that same TB.


Justin
 
Ok guys here's what I have so far. No vacuum leak. I double checked everything, and it was installed with a new gasket, so it shouldn't be leaking anyway When I crank the car without the IAC plugged in, it idles at about 1500. If I crank it when it is plugged in, it idles just over 2000. The butterfly is closed all the way. The stop screw isn't holding the throttle open at all. I even raised it way up, just to be sure it wasn't interfering. The idle screw is adjusted all the way down, it seems like if I could screw it down further I could get the right RPM, but it bottoms out. I think I need to drill out the threads. I tried a 3/8 bit but it is barely too large, and of coursse the 7/16 is too small, so I'm assuming its a metric sized hole. Any suggestions?
 
As I recall when I first got mine, years ago, I had to loosen the throttle plate screws and reposition the plate so that it would close all the way.

Just a thought. ;)
 
i have 1 and yes it did require some minor mods before it worked properly. the throttle shaft on the linkage side does have a small leak. if you spray it with break cleaner you will here the engine idle up. i fixed this by stuffing a cotton ball in there. its been about 12000 miles and no problems. you will also have to(depending on your tb) smooth out the flap edges. top outer side and bottom inner side. use around 600 grit sand paper and be careful not to remove to much. your objective is to make 1 side rounded, not actual remove any surface area. on the inner throat area you will find ribs along it from fabrication of the product. not sure if it really helps but it gave me a feel good after i polished those ribs smooth. once you do all that its one of the best tb's out there imo. and well worth the minor mods for the price that we get them for.

if you polish the ribs start with 600 grit and work your way up to 3000. at 3000 grit you will end up with a near mirror shine.
 
professional products

I put a 70mm pro product tb on my stang and it leaked through the shaft big time. started small but started whistling louder and louder. But it was pressurized with 8lbs though. There customer service tried to pull a fast one on me and sent me back the same one I'd returned. So I returned it, again, and got an accufab. But my car acted alot like what you are describing.
 
But none of you have had to drill out the idle adjustment screw? it seems like a lot of people did that when these parts were first being used.
 
Thrott;e body plate position....

It seems that I have read before the this problem you are having it possibly due to throttle plate angle after the TPS is installed. The best thing to do is to compare throttle plate angles. Remove the IAC and the TPS, mount the old throttle body and take a pic of the shaft as it comes out for the TPS, make not of the angle. Then, remove the factory throttle body and mount up the aftermarket one, again, no IAC or TPS. Again, take a pic and make note of the angle of the throttle plate by looking where the shaft comes out for the TPS. Do they match up or are they off a bit?

I think this applied to a BBK Throttle body, but your problem may be similiar:

http://www.sccoa.com/forums/showthread.php?t=115571&highlight=throttle+angle
 
When I installed mine i had the same issue but after taking it off and back on several times and fine tuning the tb sensor voltage finally got it to work the way it should. So check the tb voltage and stop screw gap.
 
It seems that I have read before the this problem you are having it possibly due to throttle plate angle after the TPS is installed. The best thing to do is to compare throttle plate angles. Remove the IAC and the TPS, mount the old throttle body and take a pic of the shaft as it comes out for the TPS, make not of the angle. Then, remove the factory throttle body and mount up the aftermarket one, again, no IAC or TPS. Again, take a pic and make note of the angle of the throttle plate by looking where the shaft comes out for the TPS. Do they match up or are they off a bit?

I think this applied to a BBK Throttle body, but your problem may be similiar:

http://www.sccoa.com/forums/showthread.php?t=115571&highlight=throttle+angle

since the PP tb has an adjustable tps mount just put it together and tether some wires out from the tps. use a test gauge to read the volts. not sure but i think .89 is ideal. then your tps is set. no a wrong setting on the tps will not cause 2k idle. typically the iac will cause the idle to go up and down. yet again will not cause 2k idle. it sounds more like he does not have it adjusted properly and did not plug up the vac leak at the throttle shaft next to the throttle link. once all leaks are plugged(USE BRAKE CLEANER ALL OVER THE TB WITH ENGINE RUNNING TO FIND LEAKS) the turn the idle screw all of the way in, unplug the iac, start the engine and see how it idles. you want about 600-700 rpm with the iac disconnected. if you cant get the idle down that low then your work on the throttle shaft and butterfly was not good enough. do it again. once you get the idle to 600-700 shut the car off. reconnect the iac. start the engine. if the idle goes up and down your iac is shot. if not then you should see about 900rpm on start up, 800 after about 3-5min, and the around 700-750 once at full operating temps. this is also depending on weather or not your tune is set right. you have to ensure your maf is set correctly along with other things.

also i only suggest this because i decided to do it while waiting for parts to come and found big problems. take off every vac line and test each one. i found about half of mine leaked. 1 wont do anything really but several will really mess with your idle.

also, are you still using the stock ic? if so with 20 or so year old sealant in that thing combined with doing upgrades you might have alot of leakage from that. i thought mine was good until i installed the dic i got from ken and went from an average of 15vac to 17.5 vac/ 15psi boost at 5200rpm to 16.5ish psi at 5200rpm.

Stephen
 
since the PP tb has an adjustable tps mount just put it together and tether some wires out from the tps. use a test gauge to read the volts. not sure but i think .89 is ideal. then your tps is set. no a wrong setting on the tps will not cause 2k idle. typically the iac will cause the idle to go up and down. yet again will not cause 2k idle. it sounds more like he does not have it adjusted properly and did not plug up the vac leak at the throttle shaft next to the throttle link. once all leaks are plugged(USE BRAKE CLEANER ALL OVER THE TB WITH ENGINE RUNNING TO FIND LEAKS) the turn the idle screw all of the way in, unplug the iac, start the engine and see how it idles. you want about 600-700 rpm with the iac disconnected. if you cant get the idle down that low then your work on the throttle shaft and butterfly was not good enough. do it again. once you get the idle to 600-700 shut the car off. reconnect the iac. start the engine. if the idle goes up and down your iac is shot. if not then you should see about 900rpm on start up, 800 after about 3-5min, and the around 700-750 once at full operating temps. this is also depending on weather or not your tune is set right. you have to ensure your maf is set correctly along with other things.

also i only suggest this because i decided to do it while waiting for parts to come and found big problems. take off every vac line and test each one. i found about half of mine leaked. 1 wont do anything really but several will really mess with your idle.

also, are you still using the stock ic? if so with 20 or so year old sealant in that thing combined with doing upgrades you might have alot of leakage from that. i thought mine was good until i installed the dic i got from ken and went from an average of 15vac to 17.5 vac/ 15psi boost at 5200rpm to 16.5ish psi at 5200rpm.

Stephen

Stephen
Are you talking about the standard head screw on top of the IAS housing ? Also have new IAS & TPSs as well
 
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