Is this a SAS screw problem?

[1Gina2G]

I just had my throttle body rebuilt, it's installed now and the car won't start with the plate closed until you press the gas petal slightly for air. so I'm assuming the plate is more closed than it should be. This deals with the SAS screw right ?

 

[T is for TURBO]

The plate can't be "more closed" than closed. There's a few things to might have to look into. Make sure you have the proper slack in the throttle cable. Making sure your TPS is showing .63 volts with the throttle plate closed (car does not need to be running, but the ignition needs to be on), make sure the ISC is functioning. Then if all checks out you may need to adjust your Base Idle Set Screw (BISS) to get the car started. Once you get the car started, you need to set the BISS so that the ISC is seeing a position of about 30 at idle with no load.

 

[snowborder714]

Incorrect. The throttle plate can be closed too far. This will cause the plate to stick when opened from letting it slam shut.

For the 2g throttle body, the SAS screw should be screwed in until the tip contacts the throttle cable bracket, and then threaded in 1 1/4 of a turn further. Then you tighten the nut down while keeping the screw from moving.

As mentioned before, open the throttle body the whole way and let it slam shut, then try to open it again. This is best done by hand with the cable disconnected. If you experience any sticking or trouble opening it, the screw isn't far enough in. Then reconnect throttle cable, remove slack (without having throttle plate open at all), and bolt it down.



But all the other stuff Shawn mentioned should also be checked as it all can affect idle.

 

[T is for TURBO]

Incorrect. The throttle plate can be closed too far. This will cause the plate to stick when opened from letting it slam shut.

Hmm.. Now that I think about it, I had that problem when I rebuilt mine. Though mine was more of a misalignment of the the throttle plate on the shaft. Since there is a cunts hair of tolerance built into the screw holes, and the machined flat on the shaft, the plate was just crooked enough to cause it to stick. What I did to fix that was, with the throttle body still on the manifold, I loosened the two screws on the throttle plate shaft just a little bit, then I opened the throttle about 10% or 15% by and, and let it slam shut. I then re-tightened the screws. The sticking problem when away after that.

 

[FeaR-GSX]

I had to give mine gas to start as well, so i replaced al he gaskets, BISS o-ring and reset it to 2 full turns out from fully closed, and reset the SAS screw to 1 1/4 turns in from when it touches the plate. I started it and adjusted the BISS from there and now it cold starts perfectly

 

[1Gina2G]

Incorrect. The throttle plate can be closed too far. This will cause the plate to stick when opened from letting it slam shut.

For the 2g throttle body, the SAS screw should be screwed in until the tip contacts the throttle cable bracket, and then threaded in 15/16's of a turn further. Then you tighten the nut down while keeping the screw from moving.

As mentioned before, open the throttle body the whole way and let it slam shut, then try to open it again. This is best done by hand with the cable disconnected. If you experience any sticking or trouble opening it, the screw isn't far enough in. Then reconnect throttle cable, remove slack (without having throttle plate open at all), and bolt it down.



But all the other stuff Shawn mentioned should also be checked as it all can affect idle.

Thanks for the explanation, i was sure the throttle was supposed to be open the smallest bit just to break the air tight seal. So this should mean that when I recently adjusted the TPS to. 63,. that it's really not at. 63 correct? So I would readjust the TPS after I move the screw.

Wondering why you said 15/16s of a turn on the screw when the VFAQ suggests only a 1/4 of a turn?

I know both my sensors work from my meter and I was using evoscan to adjust TPS voltage and position, is there any position percentage I could check through evoscan to make sure it closes where it's supposed to?

thanks again.

 

[snowborder714]

I corrected my post above to say 1 1/4 turn per the FSM.

I'd at least verify TPS adjustment if SAS adjustment is needed. I would think it might affect it since you're opening/closing throttle body, but it might be minor enough not to really matter.

 

[1Gina2G]

I corrected my post above to say 1 1/4 turn per the FSM.

I'd at least verify TPS adjustment if SAS adjustment is needed. I would think it might affect it since you're opening/closing throttle body, but it might be minor enough not to really matter.

Thanks again. What's FSM? bad with abbreviations haha.

so the the plate should probably close at %1 ? if it needs the smallest amount of air.while closed?

just taking a guess of how it would work on evoscan. I'll post what I find out by myself if no one knows.

 

[snowborder714]

FSM = Factory service manual

Your TPS values will still need to be the same (.63v at 0%), but the throttle plate just won't be quite as closed.

 

[1Gina2G]

The TPS values won't change after adjusting the plate to where its supposed to be when closed? (slightly open correct? )

 

[snowborder714]

Yes, they might change, so you might have to adjust them back. Just check the values after you adjust.

 

[DeadlyScone]

Yes, they might change, so you might have to adjust them back. Just check the values after you adjust.

do you adjust the 1g sas the same as what you mentioned above?

 

[1Gina2G]

Alright, out here in the car right now with the laptop and evoscan. After checking out the postion percentage before I do anything, it says fully closed is %12.54901 roughly each time it fully closes with the cable still attached as well.

I guess the cables also not adjusted right since it varies time to time pushing the petal all the way down. It varies between %90-%92.5 at WOT.

going to check out everything again once I disconnect the cable and back off the screw and do the 1/4 turn.

My TPS voltage is still .63 as I set it but I guess that probably about to change right now.

Now with the cable removed, the plate was still resting at %12.54 but it could now reach basically %100.

This is where I'm confused now: after backing out the SAS the plate seemed to be closing more like it was actually not fully air tight like I've been assuming. How could this be? Can the BISS interfere with start up?

It went to %12.15 and the next value was %11.767. With the SAS fully backed out, the plate doesn't close any farther than %11.767, so I'm assuming THAT is truly closed. But it makes me wonder if the SAS was already in place the whole time or if it was just my BISS I overlooked the whole time.

 

[snowborder714]

do you adjust the 1g sas the same as what you mentioned above?

Nope. With the 1g unit (which is actually the idle switch), you should technically measure it based on resistance.

Here's how I typically do it.
http://www.dsmtuners.com/forums/151826306-post2.html

 

[1Gina2G]

Alright well as I was saying towards the end ^^ and now that I'm also done checking things out for today since it got dark out.

With the stoping screw just 1/4 inwards, the TPS Percentage was back at %12.54, so I'm guessing the SAS was postioned correctly from the manufacturer but then I also started reading some things about the BISS, not sure if it's possible for the BISS to keep a car from starting but my screw was screwed in all the way so I did 2 entire rotations to the left to be "roughly the same area" I know it's not exact I will adjust later, but I'm going to see how the car starts by itself with the BISS changed...

with the removal and reinstallation of both the throttle cable and the SAS screw, the TPS voltage stayed the same, and is still at .63v

 

[T is for TURBO]

Hmmm, I must be lucky. I don't even have the a stop screw (idle switch since I have a 1g TB) in my throttle body, and I have zero problems getting my car to start, and my TPS is .63v closed and 5.00v open, no sticking, rock solid ISC.

 

[snowborder714]

No sticking with no idle switch?

Go disconnect the throttle cable, open the throttle body by hand and let it slam shut. Then try to open it again by hand. It should require no effort to open. If it doesn't, then there's something else funky about yours - possibly the plate is still misaligned.

 

[T is for TURBO]

No sticking with no idle switch?

Go disconnect the throttle cable, open the throttle body by hand and let it slam shut. Then try to open it again by hand. It should require no effort to open. If it doesn't, then there's something else funky about yours - possibly the plate is still misaligned.

That would be correct.

I have already done the test described above when I installed it. No sticky. The plate was misaligned after I rebuilt it (my fault), which defiantly caused it to stick, I could feel it in the pedal and it wouldn't close all the way once revved. I could actually see the misalignment when I took the TB off for inspection. I took the TB back off the car and realigned the plate and the stick went away.

This is why I originally made my first statement in post #2. Mine closes all the way. No throttle stop, no sticking. I have no explanation as to why it works, it just does.

 

[1Gina2G]

Alright everyone. I know my throttle body is perfect now, its fully rebuilt with new seals, all new sensors, postioned to the correct spot using evoscan. My guess was right in that the SAS was already correctly postioned, but the BISS was screwed in tightly all the way, so I then backed it out as close as I could to 2 entire revolutions and today, it started right up! It was alot smoother and I didn't have to press the gas petal at all and the idle is also sounding pretty good. I finally got to do the 30 minute break in procedure holding it at around 3K.

This was also after I adjusted the throttle cable so it would feel smooth as you press it in and works just as good as pulling the TB lever by hand

Was suprised and happy because I haven't seen any no start threads relating to the BISS, but I really think it was the problem.

 

[1Gina2G]

I wanted to mark this as resolved but wasn't sure if it was fully correct to say it was the BISS. can the BISS cause a no start?

 

[snowborder714]

I would think it would be possible if it was backed out too far, since most cars will want to die if you do that.

 

[1Gina2G]

how about screwed into far like mine was? I swear backing out the 2 full revolutions fixed my problem.

 

[snowborder714]

I wouldn't think the BISS screwed in all the way would cause that.

 

[Diamond Star Werks]

If the biss is screwed all the way in it will cause the car not too run if you dont use the gas. Touch the pedal it will start and run. It will die if you dont keep it alive with the gas. Personal experience.

I wouldn't say it cause it to not start at all, but it would make make it to not want to start/have trouble starting if you stayed off the gas.

Screwing it all the way in cuts off the air it needs to idle and causes the ecu to not be able to put the isc in the correct position for start and idle.

You need to screw your idle screw or throttle plate stop screw in till it just starts to move the plate. Best to be looking at tps value to see when it starts to open. Then adjust your tps correctly.

Then screw your biss screw all the way in then back out two full turns. Then check isc value and adjust biss till isc value equals 30 at idle.

You should not have a problem after that.

 

[PFC_CiarlilloM]

can someone elaborate a little more about the "30 minute break in period" stated in post #19