Throttle body Screw

[kingrobda2nd]

first off id like to say hello to everyone on the forum this is my first post.... my mother recently bought a mazda 6 , and i have now taken over her 99 mazda protege lx (slowest car in the world BTW) anyway.. her idle was a little low so i tried to adjust the idle screw( turns out from what i read it is the throttle body screw ) ... so i just wanted to know A) will me playing with that screw have messed up something? B) what is the correct position for the screw ?.. thanks in advance for any help you can give... i dont really know how to post pics but ill try anyway...
ok well i tried but you can only download it as attachment.. so if anyone can help me put a pic up thanks for that also... ( probably html code ) :bs:

 

[kingrobda2nd]

anyone?????

 

[GirlRacer]

did anything change when you moved the screw?

can you post a better image of the throttle body, is there a vacuum line or sensor on the opposite side?

 

[kingrobda2nd]

i will take new pics of the TB tomorrow .. i didnt notice anything at first until a few days ago .. to me it seems a lil sluggish ( could just be in my head though )...it did make the exhaust a lil louder too..

 

[kingrobda2nd]

Ok well i finally took new pics... they arent great ... i guess i need a new digi cam.. please if anyone can tell me how many turns of the screw to get it in the right position..( i know i should have made a mark with a marker to remember the position but i didnt think of that when i started) (chair) ..

Here is the screw...

here is the hose in the back of the screw

and here is Something that isnt bolted onto anything..its just haning there..
the hose from the screw leads to this "thing"

 

[shane02pro5]

That is the throttle bypass screw which when loosened allows for more air to flow around the throttle plate to aid in idle when accessories load down the motor like a/c compressor or power steering pump. Anyway I slightly adjusted mine out a little when I installed my turbo kit. Protege's are notorious for rough idle. You should be able to hear with the a/c off if you gently tighten it all the way down. It will close off the air flow and then back it out around 5-360 degree turns back out. You should slightly hear the air start to flow inside the throttle body. If you back it out too much idle will start to raise a little and then loudly bleed air out the screw hole, way too much.

When you adjust your idle which I'm sure you figured out is the one that is set into the throttle cable. On my 02 P5 anyway need to un-plug the Idle air control motor connector while car is running which is attached to the throttle body in a brass colored casing with a small motor in it. After you make your adjustment maybe 1/4 turn clockwise plug back in the connector and turn the car off. Then reset your computer by unhooking you're neg battery terminal for 15 mins, hook it back up and your done.

Good Luck!

 

[shane02pro5]

That thing hanging down in your last pick is the pressure switch for the idle bypass which is usually attached to the stock air intake piping close to the throttle body. The person that had the car before may have hade an aftermarket in take on it and never put it back to the stock piping. I have mine zip-tied to my brake booster vac line.

 

[zerocover]

I was under the impression that we cannot adjust the idle. Ie the ecu controles it with the a/f, and would learn around it if anything changed.

This is very interesting to me. I think Ill go try and lower my idle. Rough idle on msp exhaust= crazy rummbly at idle.

 

[shane02pro5]

My problem was the same with my turbo kit. I adjusted the wrong screw but later found out that my solution was backing out the bypass screw around 1-1/2 turns from stock setting which kept it more stable at idle. So I never actually kept my idle screw adjusted, only the bypass screw. The idle screw adjustment was just from reading into it in the forums.

 

[kingrobda2nd]

Protege's are notorious for rough idle. You should be able to hear with the a/c off if you gently tighten it all the way down. It will close off the air flow and then back it out around 5-360 degree turns back out. You should slightly hear the air start to flow inside the throttle body. If you back it out too much idle will start to raise a little and then loudly bleed air out the screw hole, way too much

i tightened it all the way down and then tried the 5-360 degree turns.. i only got maybe 3 turns and the air started bleeding like crazy..(mj) so i dunno.. .. to me it seems when i loosen instead of tighten it i lose alot of TQ (is that possible?) I drove around with the screw turned maybe 2 -360 degree turns and its shifting like crap and i have like no power (yes even less then i had before) the way it is now i think id get tore up by a Geo Metro with 800,000 miles towing a trailer.....

maybe the nut just fell off on the idle bypass cause my mom was the original owner of the car and i doubt she upgraded the TB ..ill have to look out for her at the track!!!

 

[shane02pro5]

There is no nut on that screw, it is just like a set screw that closes off a cavity that runs around the throttle plate. What exactly is the car doing and when is it doing it. Is it surging up and down or consistantly low. You could have a bad IAC Sensor that is what holds the idle. Maybe do a search in Yahoo or something for like "99 Protege" "idle surging" the "" will search for that exact phrase. I am no mechanic but have been in and out and up and every aspect of my P5. Could be something as minor as a crack in a vacuum line around a pressure switch. Try and spray carburator cleaner around all of the vac lines and listen for a slight raise in idle while moving the hoses around. That would be my first look.

Adjusting the Bypass screw should not effect the power but you may need to tighten it down a hair. Did you find where the Pressure switch is supposed to be fastened to? Someone was under there doing something to it if it was just hanging loose. Could be related if maintenance was done and something was left undone. Do you get a check engine light?

 

[kingrobda2nd]

k i got ya..... lol got another problem now!!! it sounds like my friggin car is electric ,the engines got this weird whinning sound on idle and while driving.. that is the only way i can explain the sound...it gets louder as i accelerate.. i have heard this whinning sound before but not this loud(almost not noticable) got any clues what that could be??? also BTW the CEL isnt on and i have just drivin maybe 100 miles with my aftermarket radio blasting , so i do not think it would be the altenator , or maybe i am wrong....

 

[kingrobda2nd]

k... it was the altenator!!! which is weird cause i have been blasting my stereo using the A.C. and the battery never died... anyway got it done today and is working perfectly...