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1FSTBRD
04-27-2015, 01:08 PM
I'd searched on here and obviously, there are quite a few of these threads, but here's another--I just couldn't get mine to run right, at all--hanging idle, idled high, etc. I'd adjusted the TPS with a voltmeter/ ohmmeter to read .95V. I'd adjusted the idle bypass screw in a few positions (closed, 1/4 turn, more than that)--no go. I'd adjusted the stop screw properly--still a problem. IAC is good--it was running fine on my stock TB, and was fine after I'd put the stock TB back on the car. After the 75mm wasn't running right, i'd also put some rtv around the IAC gasket, just in case--no dice. I'd sprayed around the throttle body for vacuum leaks--nothing.

:mad::mad:

KMT
04-27-2015, 01:33 PM
I'd sprayed around the throttle body for vacuum leaks--nothing.


Sprayed what? Be sure that the computer isn't correcting & smoothing things out faster than you can try to affect it.

What does the idle do if you disconnect the IAC when the engine is warm?

1FSTBRD
04-27-2015, 01:49 PM
I sprayed the throttle body area with carb cleaner. I didn't disconnect the IAC...if I put the 75mm back on, i'll check that. If the IAC was disconnected, would that be to rule out the IAC, itself?

KMT
04-27-2015, 02:38 PM
It's just an idea to help gather data points towards figuring out what's really wrong - especially if you have more than one issue in play.

Be sure to pull codes as well.

shoalcracker
04-27-2015, 07:01 PM
The fix if required is pretty simple if it is the TB.

Pull the shaft, check the O Rings and replace as required.

RTV'd the shaft end blockers in place on re assembly.

Good luck
Paul

Jacob_Royer
04-27-2015, 09:55 PM
I've had two pp throttle bodies and never had a problem! In fact I like
them more than the mp throttle bodies because of the tps adjustability

DrFishbone
04-28-2015, 12:03 PM
I'd searched on here and obviously, there are quite a few of these threads, but here's another--I just couldn't get mine to run right, at all--hanging idle, idled high, etc. I'd adjusted the TPS with a voltmeter/ ohmmeter to read .95V. I'd adjusted the idle bypass screw in a few positions (closed, 1/4 turn, more than that)--no go. I'd adjusted the stop screw properly--still a problem. IAC is good--it was running fine on my stock TB, and was fine after I'd put the stock TB back on the car. After the 75mm wasn't running right, i'd also put some rtv around the IAC gasket, just in case--no dice. I'd sprayed around the throttle body for vacuum leaks--nothing.

:mad::mad:

Did you check to make sure the idle bypass screw hole was drilled out into the bypass passage? That was one problem with mine.

1FSTBRD
05-03-2015, 11:40 PM
Did you check to make sure the idle bypass screw hole was drilled out into the bypass passage? That was one problem with mine.

It looks like it's drilled into the bypass passage, since I can see it in there. Did they really forget to drill that passage on yours? :(

1FSTBRD
06-18-2015, 05:08 PM
Okay, I've decided to take another shot at trying to get this thing to run right. I've done Ford's recommendation for setting the base idle, and the car idles fine. The problem now still is that when decelerating, on each downshift, it revs a little bit higher and then immediately drops back down to where it should be. Some guys (on Mustang forums) have said that with these throttle bodies, that they've let the car re-learn things in regular traffic driving. I've drove my SC for maybe 50 miles now, and it's still revving higher for a second or two and then dropping back down. The TPS is set to about .95-.96, which is in the range that it should be in.

Also, I should have mentioned that I'd ported/ polished my stock plenum to have a 75mm opening to fully accept the 75mm TB. When I go back to the stock TB even with the 75mm opening, the car runs fine. It's still the same IAC, and when going back to the stock TB, it runs fine.

Any advice?

DrFishbone
06-22-2015, 09:23 AM
I think I fixed this by re-adjusting the air bypass screw...it had backed out on me and was letting too much air bypass the throttle plate.

S_Mazza
06-22-2015, 04:59 PM
Okay, I've decided to take another shot at trying to get this thing to run right. I've done Ford's recommendation for setting the base idle, and the car idles fine. The problem now still is that when decelerating, on each downshift, it revs a little bit higher and then immediately drops back down to where it should be. Some guys (on Mustang forums) have said that with these throttle bodies, that they've let the car re-learn things in regular traffic driving. I've drove my SC for maybe 50 miles now, and it's still revving higher for a second or two and then dropping back down. The TPS is set to about .95-.96, which is in the range that it should be in.

Also, I should have mentioned that I'd ported/ polished my stock plenum to have a 75mm opening to fully accept the 75mm TB. When I go back to the stock TB even with the 75mm opening, the car runs fine. It's still the same IAC, and when going back to the stock TB, it runs fine.

Any advice?

It sounds like you may be getting a smidge too much airflow past the throttle when it is closed. That is a combination of the bypass screw and the leakage around the blade. (And leakage around the shaft, of course.) If you have the screw closed, then you would have to close the blade resting position a little to restrict airflow further.

You can go lower on the TPS starting voltage, down to about 0.80V. The computer takes a baseline reading when you first start the car, so it shouldn't be confused by this. The only thing to worry about is that you don't want the blade to stick in the bore, so you can't back the screw out entirely.

1FSTBRD
06-22-2015, 06:41 PM
I had actually adjusted the throttle blade stop screw so that it wasn't a factor.....adjusted it so that the blade would seat itself. I drove it for a bit and the blade didn't stick against the TB bore. I still had the same issue, even after adjusting the TPS to compensate. The TB shaft has o-rings that appear to be snug, but there must be a fair bit of air getting past it, still.

shoalcracker
06-22-2015, 07:04 PM
You RTV'd the shaft bushings at each end back in after checking O Rings.

Paul

1FSTBRD
06-23-2015, 02:19 PM
You RTV'd the shaft bushings at each end back in after checking O Rings.

Paul

I didn't do that--should I? I didn't do it on my modified stock TB, nor on my Mustang ones, but then again, perhaps those were designed better.

shoalcracker
06-23-2015, 05:41 PM
I wasn't sure how much leakage I had past the o rings though they looked perfect..

What pushed me to rtv was one of the bushing falling out during disassembly.

I popped out the other side as well and rtv'd the pair.

They appear to be press fit and could see them going out of tolerance with hot and cold cycling.

Paul

DrFishbone
06-24-2015, 02:41 PM
The problem with air bypassing the throttle plate is that the IAC can mask the problem by simply closing a little further and bringing the idle down to normal range. When you take your foot off the throttle, the computer positions the IAC to a preset place for a moment - which is what you're noticing.

Just to verify - you have the throttle plate and bypass screw set such that the car will barely run with the IAC unplugged (fully closed), right? As soon as you unplug the IAC, it should start running very rough and/or die completely.

I don't think saying that the car needs to "relearn" anything after the throttle body swap is accurate (except maybe idle mode strategies).

S_Mazza
06-24-2015, 02:57 PM
Just to verify - you have the throttle plate and bypass screw set such that the car will barely run with the IAC unplugged (fully closed), right? As soon as you unplug the IAC, it should start running very rough and/or die completely.

It should be able to idle without the IAC - even if just barely. Otherwise, you will have problems with rough idle and stalling when pulling into parking places.

The idle without the IAC should be like 600-650 rpm.

If you have a big low-vacuum cam, of course, you will need to go a little higher. But you will also need to make the target RPM higher in the IAC, or things will not work that well.

DrFishbone
06-24-2015, 03:10 PM
It should be able to idle without the IAC - even if just barely. Otherwise, you will have problems with rough idle and stalling when pulling into parking places.

The idle without the IAC should be like 600-650 rpm.

If you have a big low-vacuum cam, of course, you will need to go a little higher. But you will also need to make the target RPM higher in the IAC, or things will not work that well.

Correct - After the throttle plate stop and bypass screw are set properly.

Except, the IAC doesn't close when pulling into a parking spot, etc. It will be in varying positions during driving, but is rarely (if ever) closed completely.

XR7 Dave
06-24-2015, 05:02 PM
There is never a need for an IAC bypass screw on an aftermarket throttle body because a bigger TB is naturally going to bypass more air than stock, so artificially increasing it is going to be counterproductive no matter what, therefore they should always be closed completely shut. Any adjustments needed for airflow should be made using the idle stop screw.

One of the problems with the PP TB's is that the throttle blade is too thin and it flexes at times. This causes it to stick in the bore when closed abruptly from high rpm. To get the blade not to stick you have to set it a bit more open and this contributes to the problem already present from a larger than stock throttle bore naturally allowing more air to bypass the blade. Adjusting the bypass only makes it worse, never better.

Another problem that can exist with these TB's is bore to throttle blade tolerance. Sometimes the blade might be a tad small, or it might not be centered in the bore. These are manufacturing problems that may be present on one TB and not the next so it's always something to look at.

If you can't get it to idle down properly by adjusting the throttle stop then something is wrong with the TB. TPS can be set anywhere from .5v to 1.2v and still work completely fine, so don't worry about that too much. The EEC will learn the resting position and work everything relative to that.

1FSTBRD
06-24-2015, 07:04 PM
The problem with air bypassing the throttle plate is that the IAC can mask the problem by simply closing a little further and bringing the idle down to normal range. When you take your foot off the throttle, the computer positions the IAC to a preset place for a moment - which is what you're noticing.

Just to verify - you have the throttle plate and bypass screw set such that the car will barely run with the IAC unplugged (fully closed), right? As soon as you unplug the IAC, it should start running very rough and/or die completely.

I don't think saying that the car needs to "relearn" anything after the throttle body swap is accurate (except maybe idle mode strategies).

Yeah, I unplugged the IAC and it ran a little rough, and then plugged it in and it still ran rough, but then I adjusted the idle bypass screw so that it idled a bit higher and didn't run rough anymore, but it was still somewhat higher than it needed to be in order to idle correctly. Also, the hanging idle when coming out of cruising speeds when slowing down and the revving higher for a second on the downshifts just wouldn't go away. I agree that the car shouldn't have to re-learn anything, because on my Accufab for my Mustang, i'd never had any problems.

Back to stock for now. I'd ported and polished the stocker and it works well.

1FSTBRD
10-18-2015, 02:05 AM
Update: I had RTV'd the crap out of the ends of the throttle body shaft, and had also found a small vacuum leak on one of the hoses going to the intake plenum, and the throttle body works fine! No more high idle or hanging idle on downshifts. I had reset the battery, set the TPS to the proper range, and with the IAC disconnected and with the idle screw all the way in, the car died--which was good. I adjusted the screw until it idled low--just before the engine was about to die and backed it off a small bit from there.

It's difficult to tell in the low end if there's any power difference (when the tires are already roasted most of the way through 1st), but the throttle body appears to have added some power in the upper end. I've opened up the intake plenum port to match the throttle body.

FrankenBird
10-22-2015, 09:49 PM
once i had mine stalled it had 0 leaks or any high/low idle...although i had to remove the studs to get it on because the 4 holes wernt perfectly lined up. i had to rethread in the stud with the Tbody in position.No biggie.
i checked to see where the iac adjust was set at and mine was completly closed,ran exelent that way so i never touched it.

JonS
12-04-2015, 04:37 PM
I'd searched on here and obviously, there are quite a few of these threads, but here's another--I just couldn't get mine to run right, at all--hanging idle, idled high, etc. I'd adjusted the TPS with a voltmeter/ ohmmeter to read .95V. I'd adjusted the idle bypass screw in a few positions (closed, 1/4 turn, more than that)--no go. I'd adjusted the stop screw properly--still a problem. IAC is good--it was running fine on my stock TB, and was fine after I'd put the stock TB back on the car. After the 75mm wasn't running right, i'd also put some rtv around the IAC gasket, just in case--no dice. I'd sprayed around the throttle body for vacuum leaks--nothing.

:mad::mad:

To anyone: Everyone keeps pulling the TB off and on and off again. Adjusting the TPS. My PP 75mm TB is so damn tight in there bumping up against the injector wires and all lodged in behind the oil fill tube. How are you all doing these things? I had to use a swivel and two 1-inch extensions to put the IAC on after I put the TB on. I surely do NOT want to take that off three times to loosen the TPS screws and tighten them again.

What am I missing?

Q2: Where is the "stop screw" that relates to the TB butterfly plate? All I can find is the rather obvious bypass screw. (BTW, what do the PP directions mean when referencing a .010" feeler gauge? At one turn, or even many turns, the screw is still recessed in the hole.)

Q3: What the best way to put my multi-meter (volt-meter) contacts onto the TPS wires? The back of the clip faces the firewall, and I can't see anything. I think the 1 and 3 contacts / wires are the correct to read the TPS voltage? Do you stick the probes through the insulation or jam them up into the connector clip?

1FSTBRD
12-10-2015, 01:16 PM
To anyone: Everyone keeps pulling the TB off and on and off again. Adjusting the TPS. My PP 75mm TB is so damn tight in there bumping up against the injector wires and all lodged in behind the oil fill tube. How are you all doing these things? I had to use a swivel and two 1-inch extensions to put the IAC on after I put the TB on. I surely do NOT want to take that off three times to loosen the TPS screws and tighten them again.

What am I missing?

Q2: Where is the "stop screw" that relates to the TB butterfly plate? All I can find is the rather obvious bypass screw. (BTW, what do the PP directions mean when referencing a .010" feeler gauge? At one turn, or even many turns, the screw is still recessed in the hole.)

Q3: What the best way to put my multi-meter (volt-meter) contacts onto the TPS wires? The back of the clip faces the firewall, and I can't see anything. I think the 1 and 3 contacts / wires are the correct to read the TPS voltage? Do you stick the probes through the insulation or jam them up into the connector clip?

The stop screw is where the outside arm of the throttle body (on the side where the spring is). It's adjustable with an Allen key and has a small nut to adjust on it so that the Allen screw doesn't come loose or out of whack. You can do the feeler gauge thing, but if it's out of adjustment by a little bit, it won't matter that much.....there's always a small bit of air that leaks past the throttle blade (as evidenced by a pressure test), and the main idea is to prevent the throttle plate from sticking in the bore, while minimizing the amount of air that gets past the blade at idle, to keep vacuum high. When the throttle body snaps shut, you want to hear a crisp, metallic snap to it (where it's contacting the bore), rather than the dull sound of it not hitting the bore. Experiment a bit with the adjustment to do it by ear and how the throttle body feels when it closes quickly.

On the TPS removal, I can't say for sure right now, since my SC is in storage, but what I did was remove it off of the stock TB when the TB was removed from the car, and then I had put it on the PP TB when it wasn't installed on the car. The IAC, I agree.......the lower bolt is hell to get at. The first time I had removed it (to clean it for preventative maintenance), I had taken it off while the TB was still on the car, but what I had to do was pretty much go in blind to put that bolt back in, by putting it in the socket first, and then feeling around for the bolt hole with the bolt still in the socket. Not the best way to do it, since the bolt can (and usually will) fall below, which you need a magnetic tool for. You didn't mention the TB studs, but if anyone's taking the TB off, I've found that the easiest way to do it is to take out the top two studs, otherwise it's a nightmare putting it back on, because the oil filler tube is a hassle.

The wires for the TPS, what I do is gently take out that rubber thing that holds the wires in, so that there's a more accessible length of wire. I stick a claspable pin into it and clasp the pin shut.....it gives a nice, big metal surface to stick the probe to. Jamming it up into the connector clip, there's no real assurance of a connection, I find.

JonS
12-10-2015, 11:15 PM
The stop screw is where the outside arm of the throttle body (on the side where the spring is). It's adjustable with an Allen key and has a small nut to adjust on it so that the Allen screw doesn't come loose or out of whack. You can do the feeler gauge thing, but if it's out of adjustment by a little bit, it won't matter that much.....there's always a small bit of air that leaks past the throttle blade (as evidenced by a pressure test), and the main idea is to prevent the throttle plate from sticking in the bore, while minimizing the amount of air that gets past the blade at idle, to keep vacuum high. When the throttle body snaps shut, you want to hear a crisp, metallic snap to it (where it's contacting the bore), rather than the dull sound of it not hitting the bore. Experiment a bit with the adjustment to do it by ear and how the throttle body feels when it closes quickly.

On the TPS removal, I can't say for sure right now, since my SC is in storage, but what I did was remove it off of the stock TB when the TB was removed from the car, and then I had put it on the PP TB when it wasn't installed on the car. The IAC, I agree.......the lower bolt is hell to get at. The first time I had removed it (to clean it for preventative maintenance), I had taken it off while the TB was still on the car, but what I had to do was pretty much go in blind to put that bolt back in, by putting it in the socket first, and then feeling around for the bolt hole with the bolt still in the socket. Not the best way to do it, since the bolt can (and usually will) fall below, which you need a magnetic tool for. You didn't mention the TB studs, but if anyone's taking the TB off, I've found that the easiest way to do it is to take out the top two studs, otherwise it's a nightmare putting it back on, because the oil filler tube is a hassle.

The wires for the TPS, what I do is gently take out that rubber thing that holds the wires in, so that there's a more accessible length of wire. I stick a claspable pin into it and clasp the pin shut.....it gives a nice, big metal surface to stick the probe to. Jamming it up into the connector clip, there's no real assurance of a connection, I find.

Thanks! Throttle stop screw was a terminology problem on my part. I had adjusted that before I stuck the TB on and didn't even think that's what the previous posts were referring to.

Roger that second screw on the IAC. I can now do that in a minute or so from practice. I'm going to try jumper or shunt wires on the TPS. I plan to avoid pulling the TB. It's just too tight in there.

S_Mazza
12-11-2015, 12:38 AM
Thanks! Throttle stop screw was a terminology problem on my part. I had adjusted that before I stuck the TB on and didn't even think that's what the previous posts were referring to.

Roger that second screw on the IAC. I can now do that in a minute or so from practice. I'm going to try jumper or shunt wires on the TPS. I plan to avoid pulling the TB. It's just too tight in there.

I like this type of thing for backprobing connectors.

http://www.target.com/p/300-pearlized-ball-head-straight-pins-size-24-1-1-2/-/A-17458081?ci_src=17588969&ci_sku=17458081&ref=tgt_adv_XS000000&AFID=google_pla_df&CPNG=PLA_Appliances%2BShopping&adgroup=SC_Appliances&LID=700000001170770pgs&network=g&device=c&location=9007374&gclid=CPOzrKb-0skCFYM8aQodZBgCcQ&gclsrc=aw.ds

(Color is up to you. :p)

1FSTBRD
12-11-2015, 10:22 AM
If the tightness in there is bothering you to work properly, what I do is remove the top two bolt studs.....the TB always seems to have a problem being taken off or being put back on, due to the oil filler cap. I take a pair of vice grips and grip it on the non-threaded part of the stud.

JonS
12-11-2015, 09:17 PM
If the tightness in there is bothering you to work properly, what I do is remove the top two bolt studs.....the TB always seems to have a problem being taken off or being put back on, due to the oil filler cap. I take a pair of vice grips and grip it on the non-threaded part of the stud.

That's a great idea - and why I asked in this forum

JonS
12-11-2015, 09:27 PM
She's idling perfectly and driving well. All those posters who insisted it just took some fiddling were right. The pro products TB upgrade is a great choice.

It did NOT help that the 2V setting on my multimeter only read accurately if I pushed down on the dial .... long story.

I do not like the iac gasket in the kit. I duplicated the original gasket. The tps adjustment is a ~~~~, but works if you follow the directions and take everything off and on three times.