Accufab is the brand. Idles around 1000 RPM's. TPS sensor was set .99 volts. Backed idle set screw out (all the way) and it will idle down to 850 in neutral. Even tried using Predator to lower the idle, but in true form, it did nothing either. Idle "hangs up" around 1100-1200 for several seconds before coming down. Is the Accufab SBTB generally a POS? I also put the C&L plenum on at the same time, but I don't think it's the problem. I checked all bolts for tightness (three times) and vacuum hoses (four times).

I am about to put the factory throttle body back on. If I try another Accufab, am I wasting my time? Is there a different brand (single blade) that is close being as good in quality as a factory piece? I know there is Billet-Flow, but I don't know much about their reputation. If all single blade throttle bodies idle high, and hang up at even higher RPM's for several seconds, I'll go back to the stock one.

Any suggestions?

Thanks,
Greg

 

you are turning the screw the wrong way....

1) adjust the "stop screw" so that the throttle lever is touching stop screw at idle

2)reset computer

3)adjust the TPS

4)reset computer

you should be fine after that

 

installed my SBTB from accufab two days ago no problems and looks great!

 

I had no problems except had to use a stiffer return spring as the stock spring would hang open when I would stab the throttle.

 

Thanks for your advise. Let me respond to them in order.

1. I tried the set screw "as-is" out of the box, I adjusted the TPS @ .99, and it idled too high. Had no choice but to back set screw out, slowed it down (some). If I set it to touch enough to prevent "sticking," the idle increases slightly (back up to 900-950 RPM).

2. I didn't try that, although I read a bunch of posts on throttle body installation/problems and most who disconnected /reconnected their battery noticed no difference (I will try it though).

3. Done (as my original post states) and after backing the set screw out, the TPS voltage dropped down to .98 volts.

4. Same as #2. I will try disconnecting the battery.

Thanks.

 

I don't think you understand

What I posted was not a suggestion, it is the steps you must do in order to install a TB correctly

You must do all of the steps above in order

The screw is not an idle adjustment

The lever must touch the stop screw every time

Your IAC is what adjusts the idle speed

Even though you "open the blade a bit by having the lever touch the screw" the IAC will close some and bring the idle back down

I know, it's opposite of what you might think but my steps that I have outlined in my above post are correct none the less

Good luck

 

I'm used to the 5.0 Mustangs.

I adjusted the stop screw to hit just barely so as to eliminate binding/sticking.
Why does the computer have to be reset BEFORE adjusting the TPS? Afterwards, makes sense.
I have spent hours trying every which combination, including numerous computer resets with TPS anywhere between .97-.99 with the throttle blade set on the stop, to the stop being backed all the way out.
Results were always the same: 850 RPM in park, and idle "hangs up" around 1300-1400 RPM's for over 5 seconds at a time.
I put the stock TB back on and it runs perfect.
I believe the Accufab is not the best (consistent) in quality.

By the way, everybody thinks there is more throttle response. THAT'S THE PLACEBO EFFECT. Absolutely the same throttle response, and no change in seat of the pants feel.

 

I gained .2 and 2 mph with only a tb change. I'm at about 470whp. No placebo effect here. You can fix your Idle problem with your tune if you know what your doing. I don't but my tuner does.

 

here is a description of the operation of the closed throttle postion from the ford service cd:

Idle Speed Control Closed Throttle Determination

One of the fundamental criteria for entering rpm control is an indication of closed throttle. Throttle mode is always calculated to the lowest learned throttle position (TP) voltage seen since engine start. This lowest learned value is called "ratch", since the software acts like a one way-ratch. The ratch value (voltage) is displayed as the TPREL PID. The ratch value is relearned after every engine start. Ratch will learn the lowest, steady TP voltage seen after the engine starts. In some cases, ratch can learn higher values of TP. The time to learn the higher values is significantly longer than the time to learn the lower values. The brakes must also be applied to learn the longer values.

All PCM functions are done using this ratch voltage, including idle speed control. The PCM goes into closed throttle mode when the TP voltage is at the ratch (TPREL PID) value. Increase in TP voltage, normally less than 0.05 volts, will put the PCM in part throttle mode. Throttle mode can be viewed by looking at the TP MODE PID. With the throttle closed, the PID must read C/T (closed throttle). Slight corrupt values of ratch can prevent the PCM from entering closed throttle mode. An incorrect part throttle indication at idle will prevent entry into closed throttle rpm control, and could result in a high idle. Ratch can be corrupt by a throttle position sensor or circuit that "drops out" or is noisy, or by loose/worn throttle plates that close tight during a decel and spring back at normal engine vacuum.

Hope that helps you find the root of the problem.

 

Where is BadBolt when ya need him ?

Dan

 

Very helpful.

Assume for a moment you are talking to a two-year old... when you say "Reset Computer", do you mean...

1. Reload program?
2. Reflash PCM?
3. Power cycle the truck?
4. Something else?

THANKS

 

Probably disconnect the battery, and ground both positive anc negative cables to a ground. Then let it sit for a minute or two and hook it back up.

 

accufab gives a small bag with 2 screws in it with every SBTB.
in that bag is a paper that states in all CAPS.......DO NOT ADJ. SET SCREW TO ADJST IDLE IT IS SET AT THE FACTORY.....so the oly way to set your idle is by TPS.


i just put mine on last night.......i used a drill and took out the
metal in the TPS wholes and adjusted to .998 and it runs/idles great


dustin

 

It seems that some are not reading my posts, with regard to what I've already tried. I have tried the factory set set screw stop, and tried backing it out as much as all the way. Each time I tried something, I also made sute the TPS voltage was at .98-.99 and I disconnected the battery, even taking both cables off the battery and touching them together to cancel out any voltage saved in any capacitors. NO MATER WHAT I DID, the idle was high.

2B Screwed, I still maintain the SBTB give no "throttle response." I never said zero HP pick-up, but it is a well established fact that around 350-400 RWHP the HP pickup is minimal to almost none. You are at a HP level where it starts to make a sizeable difference (probably 550 Flywheel). Anyway, I feel I know what I'm doing with regard to knowing how to sett the adjustments where they are reportedly supposed to be, and I am at the point where I believe the quality control/consistency on the Accufab piece can be called into question.

 

I have never heard of any one local having a problem with them, but I have read on here people having Idle problems after the plenum, something about the egr valve or something. I know in general accufab is one of the best at what they do. Never had a problem on any of the Mustangs I've had or been around either.